Every wireless communication system involves a transmitter that transmits some sort of signal (voice, video, data, etc[[Image:Splash-prop.)jpg|right|720px]]<strong><font color="#4e1985" size="4">True 3D, a receiver that receives and detects the transmitted signalCoherent, and a channel in which the signal is transmitted into the air and travels from the location of the transmitter to the location of the receiverPolarimetric Ray Tracer That Simulates Very Large Urban Scenes In Just Few Minutes!</font></strong><table><tr><td>[[image:Cube-icon. The channel is the physical medium in which the electromagnetic waves propagatepng | link=Getting_Started_with_EM. The successful design of a communication system depends on an accurate Cube]] [[image:cad-ico.png | link budget analysis that determines whether the receiver receives adequate signal power to detect it against the background noise=Building_Geometrical_Constructions_in_CubeCAD]] [[image:fdtd-ico. The simplest channel is the free spacepng | link=EM. Real communication channels, however, are more complicated and involve a large number of wave scatterersTempo]] [[image:static-ico. For example, in an urban environment, the obstructing buildings, vehicles and vegetation reflect, diffract or attenuate the propagating radio wavespng | link=EM. As a result, the receiver receives a distorted signal that contains several components with different power levels and different time delays arriving from different anglesFerma]] [[image:planar-ico.png | link=EM.Picasso]] [[image:metal-ico.png | link=EM.Libera]] [[image:po-ico.png | link=EM.Illumina]]</td><tr></table>[[Image:Tutorial_icon.png|30px]] '''[[EM.Cube#EM.Terrano_Documentation | EM.Terrano Tutorial Gateway]]'''
The different rays arriving at a receiver location create constructive and destructive interference patterns[[Image:Back_icon. This is known as the multipath effectpng|30px]] '''[[EM. This together with the shadowing effects caused by building obstructions lead Cube | Back to channel fading. In many wireless applications, the total received power by the receiver is all that matters. In some others, the angle of arrival of the rays as well as their polarization are of immense interest. A fully polarimetric, coherent ray tracer like EM.CubeMain Page]]'s Shooting-and-Bouncing-Rays (SBR) solver lets you compute and resolve all the rays received by a receiver including their power levels, time delays and angles of arrival.''==Product Overview==
[[File:urban===EM.png]]Terrano in a Nutshell ===
== A Wireless Propagation Primer ==EM.Terrano is a physics-based, site-specific, wave propagation modeling tool that enables engineers to quickly determine how radio waves propagate in urban, natural or mixed environments. EM.Terrano's simulation engine is equipped with a fully polarimetric, coherent 3D ray tracing solver based on the Shooting-and-Bouncing-Rays (SBR) method, which utilizes geometrical optics (GO) in combination with uniform theory of diffraction (UTD) models of building edges. EM.Terrano lets you analyze and resolve all the rays transmitted from one ore more signal sources, which propagate in a real physical channel made up of buildings, terrain and other obstructing structures. EM.Terrano finds all the rays received by a receiver at a particular location in the physical site and computes their vectorial field and power levels, time delays, angles of arrival and departure, etc. Using EM.Terrano you can examine the connectivity of a communication link between any two points in a real specific propagation site.
=== Free Space Propagation Channel ===Since its introduction in 2002, EM.Terrano has helped wireless engineers around the globe model the physical channel and the mechanisms by which radio signals propagate in various environments. EM.Terranoâs advanced ray tracing simulator finds the dominant propagation paths at each specific physical site. It calculates the true signal characteristics at the actual locations using physical databases of the buildings and terrain at a given site, not those of a statistically average or representative environment. The earlier versions of EM.Terrano's SBR solver relied on certain assumptions and approximations such as the vertical plane launch (VPL) method or 2.5D analysis of urban canyons with prismatic buildings using two separate vertical and horizontal polarizations. In 2014, we introduced a new fully 3D polarimetric SBR solver that accurately traces all the three X, Y and Z components of the electric fields (both amplitude and phase) at every point inside the computational domain. Using a 3D CAD modeler, you can now set up any number of buildings with arbitrary geometries, no longer limited to vertical prismatic shapes. Versatile interior wall arrangements allow indoor propagation modeling inside complex building configurations. The most significant recent development is a multicore parallelized SBR simulation engine that takes advantage of ultrafast k-d tree algorithms borrowed from the field of computer graphics and video gaming to achieve the ultimate speed and efficiency in geometrical optics ray tracing.
In a free-space line-of-sight (LOS) communication system, the signal propagates directly from the transmitter to the receiver without encountering any obstacles (scatterers)[[Image:Info_icon. Electromagnetic waves propagate in the form of spherical waves with a functional dependence of e<sup>j(ω</sup><sup>t-k<sub>0</sub>R)</sup>/R, where R is the distance between the transmitter and receiver, <math>\omega = 2\pi f</math>, f is the signal frequency, <math>k_0 = \tfrac{\omega}{c} = \tfrac{2\pi}{\lambda}</math>, c is the speed of light, and λ<sub>0</sub> is the free-space wavelength at the operational frequency. By the time the signal arrives at the location of the receiver, it undergoes two changes. It is attenuated and its power drops by a factor of 1/R<sup>2</sup>, and additionally, it experiences a phase shift of <math>\tfrac{2\pi R}{\lambda_0}</math>, which is equivalent to a time delay of R/c. The signal attenuation from the transmitter png|30px]] Click here to learn more about the receiver is usually quantified by '''Path Loss[[Basic Principles of SBR Ray Tracing | Basic SBR Theory]]''' defined as the ratio of the received signal power (P<sub>R</sub>) to the transmitted signal power (P<sub>T</sub>). Assuming isotropic transmitting and receiving radiators (i.e. radiating uniformly in all directions), the Path Loss in a free-space line-of-sight communication system is given by Friisâ formula:
<table><tr><td> [[FileImage:friis1Manhattan1.png|thumb|left|420px|A large urban propagation scene featuring lower Manhattan.]]</td></tr></table>
The above formula assumes that the receiving antenna is polarization-matched=== EM. Normally, there is a polarization mismatch between Terrano as the transmitting and receiving antennasPropagation Module of EM. In the case of directional transmitting and receiving antennas, Friisâ formula takes the following form:Cube ===
EM.Terrano is the ray tracing '''Propagation Module''' of '''[[File:friis2EM.pngCube]]''', a comprehensive, integrated, modular electromagnetic modeling environment. EM.Terrano shares the visual interface, 3D parametric CAD modeler, data visualization tools, and many more utilities and features collectively known as [[Building_Geometrical_Constructions_in_CubeCAD | CubeCAD]] with all of [[EM.Cube]]'s other computational modules.
where '''u<sub>T</sub>''With the seamless integration of EM.Terrano with [[EM.Cube]]' s other modules, you can now model complex antenna systems in [[EM.Tempo]], [[EM.Libera]], [[EM.Picasso]] or [[EM.Illumina]], and '''u<sub>R</sub>''' are generate antenna radiation patterns that can be used to model directional transmitters and receivers at the unit polarization vectors two ends of your propagation channel. Conversely, you can analyze a propagation scene in EM.Terrano, collect all the transmitting rays received at a certain receiver location and receiving antennasimport them as coherent plane wave sources to [[EM.Tempo]], and G<sub>T</sub> and G<sub>R</sub> are their gains[[EM.Libera]], respectively[[EM.Picasso]] or [[EM.Illumina]].
[[FileImage:losInfo_icon.png|30px]]Figure 1: A Line-of-Sight (LOS) Propagation ScenarioClick here to learn more about '''[[Getting_Started_with_EM.Cube | EM.Cube Modeling Environment]]'''.
=== Multipath Propagation Channel Advantages & Limitations of EM.Terrano's SBR Solver ===
FreeEM.Terrano's SBR simulation engine utilizes an intelligent ray tracing algorithm that is based on the concept of k-dimensional trees. A k-d tree is a space line-ofpartitioning data structure for organizing points in a k-sight communications is an ideal scenario that is typically used to model aerial or dimensional space applications. In groundk-based systems, the presence of the ground d trees are particularly useful for searches that involve multidimensional search keys such as range searches and nearest neighbor searches. In a very typical large reflecting surface affects the signal radio propagation to scene, there might be a large extent. Along the path number of rays emanating from a the transmitter to a receiver, the signal that may also encounter many never hit any obstacles and scatterers such as buildings. For example, vegetation, etc. In upward-looking rays in an urban canyon environment with many buildings of different heights and other scatterers, a line of sight between propagation scene quickly exit the transmitter and receiver can hardly be establishedcomputational domain. In such casesRays that hit obstacles on their path, on the propagating signals bounce back and forth among the building surfaces. It is these other hand, generate new reflected or diffracted signals that are often received and detected by the receiver. Such environments are referred to as âmultipathâtransmitted rays. The group of k-d tree algorithm traces all these rays arriving at systematically in a specific receiver location experience different attenuations very fast and different time delaysefficient manner. This gives rise to constructive and destructive interference patterns that cause Another major advantage of k-d trees is the fast fading. As a receiver moves locally, the receiver power level fluctuates sizably due to these fading effectsprocessing of multi-transmitters scenes.
EM.Terrano performs fully polarimetric and coherent SBR simulations with arbitrary transmitter antenna patterns. Its SBR simulation engine is a true asymptotic "field" solver. The use amplitudes and phases of statistical models for prediction all the three vectorial field components are computed, analyzed and preserved throughout the entire ray tracing process from the source location to the field observation points. You can visualize the magnitude and phase of fading effects is widely popular among communication system designersall six electric and magnetic field components at any point in the computational domain. In most scenes, the buildings and the ground or terrain can be assumed to be made of homogeneous materials. These models are either based on measurement data or derived from simplistic analytical frameworksrepresented by their electrical properties such as permittivity ε<sub>r</sub> and electric conductivity σ. The statistical models often exhibit considerable errors especially in areas having mixed More complex scenes may involve a multilayer ground or multilayer building sizeswalls. In such cases, one needs to perform a physics-based, site-specific analysis of can no longer use the propagation environment to accurately identify and establish all the possible signal paths from the transmitter to the receiversimple reflection or transmission coefficient formulas for homogeneous medium interfaces. This involves an electromagnetic analysis of EM.Terrano calculates the scene with all reflection and transmission coefficients of its geometrical multilayer structures as functions of incident angle, frequency and physical detailspolarization and uses them at the respective specular points.
Link budget analysis for a multipath channel It is a challenging task due very important to the large size of the computational domains involved. Typical propagation scenes usually involve length scales keep in mind that SBR is an asymptotic electromagnetic analysis technique that is based on Geometrical Optics (GO) and the order Uniform Theory of thousands of wavelengthsDiffraction (UTD). To calculate the path loss between the transmitter and receiverIt is not a "full-wave" technique, one must solve and it does not provide a direct numerical solution of Maxwell's equations in an extremely large space. Full-wave numerical techniques like the Finite Difference Time Domain (FDTD) method, which require SBR makes a fine discretization number of assumptions, chief among them, a very high operational frequency such that the computational domainlength scales involved are much larger than the operating wavelength. Under this assumed regime, electromagnetic waves start to behave like optical rays. Virtually all the calculations in SBR are therefore impractical based on far field approximations. In order to maintain a high computational speed for solving large-scale urban propagation problems, EM. The practical solution is Terrano ignores double diffractions. Diffractions from edges give rise to use asymptotic techniques such as SBR, which utilize analytical techniques over a large distances rather than a brute force discretization number of the entire computational domainnew secondary rays. Such asymptotic techniques, The power of coursediffracted rays drops much faster than reflected rays. In other words, have to compromise modeling accuracy for practical computation feasibilityan edge-diffracted ray does not diffract again from another edge in EM.Terrano. However, reflected and penetrated rays do get diffracted from edges just as rays emanated directly from the sources do.
<table><tr><td> [[FileImage:multi1_tnMultipath_Rays.png|thumb|left|500px|A multipath urban propagation scene showing all the rays collected by a receiver.]]</td></tr></table>
Figure 1: A multipath propagation scene showing all the rays arriving == EM.Terrano Features at a particular receiver.Glance ==
=== The SBR Method Scene Definition / Construction ===
EM.Cube's [[Propagation Module]] provides an asymptotic ray tracing simulation engine that is based on a technique known as Shooting-<ul> <li> Buildings/blocks with arbitrary geometries and-Bouncing-Rays (SBR). In this technique, propagating spherical waves are modeled as ray tubes material properties</li> <li> Buildings/blocks with impenetrable surfaces or beams that emanate from a sourcepenetrable surfaces using thin wall approximation</li> <li> Multilayer walls for indoor propagation scenes</li> <li> Penetrable volume blocks with arbitrary geometries and material properties</li> <li> Import of shapefiles and STEP, travel in space, bounce from obstacles IGES and are collected by the receiver. As rays propagate away from their source STL CAD model files for scene construction</li> <li> Terrain surfaces with arbitrary geometries and material properties and random rough surface profiles</li> <li> Import of digital elevation map (transmitterDEM)terrain models</li> <li> Python-based random city wizard with randomized building locations, they begin to spread (extents and orientations</li> <li> Python-based wizards for generation of parameterized multi-story office buildings and several terrain scene types</li> <li> Standard half-wave dipole transmitters and receivers oriented along the principal axes</li> <li> Short Hertzian dipole sources with arbitrary orientation</li> <li> Isotropic receivers or diverge) over distance. In receiver grids for wireless coverage modeling</li> <li> Radiator sets with 3D directional antenna patterns (imported from other words, the cross section modules or footprint external files)</li> <li> Full three-axis rotation of a ray tube expands as a function of the distance from the source. EM.Cube uses an accurate equiimported antenna patterns</li> <li> Interchangeable radiator-angular ray generation scheme to that produces almost identical ray tubes in all directions to satisfy energy based definition of transmitters and power conservation requirements.receivers (networks of transceivers)</li></ul>
When a ray hits an obstructing surface, one or more of the following phenomena may happen:=== Wave Propagation Modeling ===
# Reflection <ul> <li> Fully 3D polarimetric and coherent Shoot-and-Bounce-Rays (SBR) simulation engine</li> <li> GTD/UTD diffraction models for diffraction from the locally flat building edges and terrain</li> <li> Triangular surfacemesh generator for discretization of arbitrary block geometries</li># Transmission <li> Super-fast geometrical/optical ray tracing using advanced k-d tree algorithms</li> <li> Intelligent ray tracing with user defined angular extents and resolution</li> <li> Ray reflection, edge diffraction and ray transmission through multilayer walls and material volumes</li> <li> Communication link analysis for superheterodyne transmitters and receivers</li> <li> 17 digital modulation waveforms for the locally flat surfacecalculation of E<sub>b</sub>/N<sub>0</sub> and Bit error rate (BER)</li># Diffraction from <li> Incredibly fast frequency sweeps of the entire propagation scene in a single SBR simulation run</li> <li> Parametric sweeps of scene elements like building properties, or radiator heights and rotation angles</li> <li> Statistical analysis of the propagation scene</li> <li> Polarimetric channel characterization for MIMO analysis</li> <li> "Almost real-time" Polarimatrix solver using an edge existing ray database</li> <li> "Almost real-time" transmitter sweep using the Polarimatrix solver</li> <li> "Almost real-time" rotational sweep for modeling beam steering using the Polarimatrix solver</li> <li> "Almost real-time" mobile sweep for modeling mobile communications between two conjoined locally flat surfacesTx-Rx pairs along a mobile path using the Polarimatrix solver</li></ul>
EM.Cube discretizes all the objects of the scene into flat triangular facets. Obviously, rectangular and cubic objects preserve their geometric shapes through this discretization. Objects with curved surfaces such as cylinders, cones or spheres, are approximated by === Data Generation "amp;polymesh" representations. The geometric fidelity of the resulting mesh depends on the specified mesh edge length. When a ray hits a triangular facet, the propagating spherical wave is approximated as a plane wave at the specular point. The reflection and transmission coefficients of the surface are calculated at the operational frequency and at the particular ray incident angle. Visualization ===
A new reflected ray is generated at the specular point<ul> <li> Standard output parameters for received power, path loss, SNR, which starts traveling E<sub>b</sub>/N<sub>0</sub> and bouncing around BER at each individual receiver</li> <li> Graphical visualization of propagating rays in the scene. If the obstructing surface is penetrable, a second transmitted ray is generated </li> <li> Received power coverage maps</li> <li> Link connectivity maps (based on minimum required SNR and added to the scene. If the BER)</li> <li> Color-coded intensity plots of polarimetric electric field distributions</li> <li> Incoming ray hits the edge of an obstacledata analysis at each receiver including delay, it is diffracted from that edge. This leads to the creation angles of a cone arrival and departure</li> <li> Cartesian plots of new rays, which greatly complicate the computational problem. The Uniform Theory path loss along defined paths</li> <li> Power delay profile of Diffraction (UTD) is used to calculate the wedge diffraction coefficients at the edges selected receiver</li> <li> Polar stem charts of scattering blocks. Note that reflection, transmission angles of arrival and diffraction coefficients are all dependent on the polarization departure of the incident plane wave.selected receiver</li></ul>
A receiver may receive == Building a large number of rays: direct line-of-sight rays from the transmitter, rays reflected or diffracted off the ground or terrain, rays reflected or diffracted from buildings or rays transmitted through buildings. Each received ray is characterized by its power, delay and angles of arrival, which are the spherical coordinate angles θ and φ of the incoming ray. The actual signal received and detected by the receiver is the superposition of all these rays with different power levels and different time delays. Most of the time, you will be interested Propagation Scene in the coverage map of an area, which shows how much power is received by a grid of receivers spread over the area from a given fixed transmitterEM.Terrano ==
=== Ray Reflection & Transmission The Various Elements of a Propagation Scene ===
The incidentA typical propagation scene in EM.Terrano consists of several elements. At a minimum, reflected you need a transmitter (Tx) at some location to launch rays into the scene and transmitted a receiver (Rx) at another location to receive and collect the incoming rays . A transmitter and a receiver together make the simplest propagation scene, representing a free-space line-of-sight (LOS) channel. In EM.Terrano, a transmitter represents a point source, while a receiver represents a point observable. Both a transmitter and a receiver are each characterized by associated with point objects, which are one of the many types of geometric objects you can draw in the project workspace. Your scene might involve more than one transmitter and possibly a triplet large grid of unit vectors:receivers.
* [[File:frml14_tn.png]] representing the incident parallel polarization vectorA more complicated propagation scene usually contains several buildings, walls, incident perpendicular polarization vector or other kinds of scatterers and incident propagation vector, respectivelywave obstructing objects.* [[File:frml15_tnYou model all of these elements by drawing geometric objects in the project workspace or by importing external CAD models.png]] representing EM.Terrano does not organize the reflected parallel polarization vectorgeometric objects of your project workspace by their material composition. Rather, reflected perpendicular polarization vector and reflected propagation vector, respectivelyit groups the geometric objects into blocks based on a common type of interaction with incident rays.* [[File:frml16_tnEM.png]] representing Terrano offer the transmitted parallel polarization vector, transmitted perpendicular polarization vector and transmitted propagation vector, respectively.following types of object blocks:
{| class="wikitable"|-! scope="col"| Icon! scope="col"| Block/Group Type ! scope="col"| Ray Interaction Type! scope="col"| Object Types Allowed! scope="col"| Notes|-| style="width:30px;" | [[File:reflectimpenet_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Impenetrable Surface | Impenetrable Surface]]| style="width:200px;" | Ray reflection, ray diffraction| style="width:250px;" | All solid & surface geometric objects, no curve objects| style="width:300px;" | Basic building group for outdoor scenes|-| style="width:30px;" | [[File:penet_surf_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Penetrable Surface | Penetrable Surface]]| style="width:200px;" | Ray reflection, ray diffraction, ray transmission in free space| style="width:250px;" | All solid & surface geometric objects, no curve objects| style="width:300px;" | Behaves similar to impenetrable surface and uses thin wall approximation for generating transmitted rays, used to model hollow buildings with ray penetration, entry and exit |-| style="width:30px;" | [[File:terrain_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Terrain Surface | Terrain Surface]]| style="width:200px;" | Ray reflection, ray diffraction| style="width:250px;" | All surface geometric objects, no solid or curve objects | style="width:300px;" | Behaves exactly like impenetrable surface but can change the elevation of all the buildings and transmitters and receivers located above it|-| style="width:30px;" | [[File:penet_vol_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Penetrable Volume | Penetrable Volume]]| style="width:200px;" | Ray reflection, ray diffraction, ray transmission and ray attenuation inside homogeneous material media| style="width:250px;" | All solid geometric objects, no surface or curve objects| style="width:300px;" | Used to model wave propagation inside a volumetric material block, also used for creating individual solid walls and interior building partitions and panels in indoor scenes|-| style="width:30px;" | [[File:base_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Base Location Set | Base Location Set]]| style="width:200px;" | Either ray generation or ray reception| style="width:250px;" | Only point objects| style="width:300px;" | Required for the definition of transmitters and receivers|-| style="width:30px;" | [[File:scatterer_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Point Scatterer Set | Point Scatterer Set]]| style="width:200px;" | Ray reception and ray scattering| style="width:250px;" | Only point, box and sphere objects| style="width:300px;" | Required for the definition of point scatterers as targets in a radar simulation |-| style="width:30px;" | [[File:Virt_group_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Virtual_Object_Group | Virtual Object]]| style="width:200px;" | No ray interaction| style="width:250px;" | All types of objects| style="width:300px;" | Used for representing non-physical items |}
The Incident, Reflected and Transmitted Rays at Click on each type to learn more about it in the Interface Between Two Dielectric Media[[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types]].
The reflected ray Impenetrable surfaces, penetrable surfaces, terrain surfaces and penetrable volumes represent all the objects that obstruct the propagation of electromagnetic waves (rays) in the free space. What differentiates them is assumed the types of physical phenomena that are used to originate from model their interaction with the impinging rays. EM.Terrano discretizes geometric objects into a virtual image source pointnumber of flat facets. The three triplets constitute three orthonormal basis systems. Belowfield intensity, it is assumed that phase and power of the two dielectric media have permittivities ε<sub>1</sub> reflected and ε<sub>2</sub>, and permeabilities μ<sub>1</sub> and μ<sub>2</sub>, respectivelytransmitted rays depend on the material properties of the obstructing facet. A lossy medium with The specular surface of a conductivity σ facet can be modeled by locally as a complex permittivity ε<sub>r</sub> = ε'<sub>r</sub> âjσ/ε<sub>0</sub>simple homogeneous dielectric half-space or as a multilayer medium. Assuming '''n''' to be the unit normal to the interface plane between the two mediaIn that respect, and Z<sub>0</sub> = 120Ω , the incident polarization vectors as well as all the reflected and transmitted vectors are found obstructing objects such asbuildings, walls, terrain, etc. behave in a similar way:
[[File:frml1* They terminate an impinging ray and replace it with one or more new rays.* They represent a specular interface between two media of different material compositions for calculating the reflection, transmission or diffraction coefficients.png]]
The reflected unit vectors An outdoor propagation scene typically involves several buildings modeled by impenetrable surfaces. Rays hit the facets of impenetrable buildings and bounce back, but they do not penetrate the object. It is assumed that the interior of such buildings are found highly dissipative due to wave absorption or diffusion. An indoor propagation scene typically involves several walls, a ceiling and a floor arranged according to a certain building layout. Penetrable surfaces are used to model the exterior and interior walls of buildings. Rays reflect off these surfaces and diffract off their edges. They also penetrate the thin surface and continue their path in the free space on the other side of the wall. Terrain surfaces with irregular shapes or possibly random rough surfaces are used as:an alternative to the flat global ground. You can also build mixed scenes involving both impenetrable and penetrable blocks or irregular terrain. In the context of a propagation scene, penetrable volumes are often used to model block of rain, fog or vegetation. Base location sets are used to geometrically represent point transmitters and point receivers in the project workspace.
[[File:frml2Sometimes it is helpful to draw graphical objects as visual clues in the project workspace. These non-physical objects must belong to a virtual object group. Virtual objects are not discretized by EM.Terrano's mesh generator, and they are not passed onto the input data files of the SBR simulation engine.png]]
The transmitted unit vectors are found as<table><tr><td> [[Image:PROP MAN2.png|thumb|left|720px|An urban propagation scene generated by EM.Terrano's "Random City" and "Basic Link" wizards. It consists of 25 cubic brick buildings, one transmitter and a large two-dimensional array of receivers. ]]</td></tr></table>
[[File:frml3.png]]=== Organizing the Propagation Scene by Block Groups ===
whereIn EM.Terrano, all the geometric objects associated with the various scene elements like buildings, terrain surfaces and base location points are grouped together as blocks based on their common type. All the objects listed under a particular group in the navigation tree share the same color, texture and material properties. Once a new block group has been created in the navigation tree, it becomes the "Active" group of the project workspace, which is always displayed in bold letters. You can draw new objects under the active node. Any block group can be made active by right-clicking on its name in the navigation tree and selecting the '''Activate''' item of the contextual menu.
<table><tr><td> [[FileImage:frml4PROP MAN1.png|thumb|left|480px|EM.Terrano's navigation tree.]]</td></tr></table>
[[File:frml5It is recommended that you first create block groups, and then draw new objects under the active block group. However, if you start a new EM.Terrano project from scratch, and start drawing a new object without having previously defined any block groups, a new default impenetrable surface group is created and added to the navigation tree to hold your new CAD object. You can always change the properties of a block group later by accessing its property dialog from the contextual menu. You can also delete a block group with all of its objects at any time.png]]
The reflection coefficients at {{Note|You can only import external CAD models (STEP, IGES, STL, DEM, etc.) only to the interface are calculated for CubeCAD module. You can then transfer the two parallel and perpendicular polarizations as:imported objects from CubeCAD to EM.Terrano.}}
[[File:frml6.png]]=== Moving Objects Among Different Block Groups ===
=== Penetration Through Thin Walls Or Surfaces ===You can move any geometric object or a selection of objects from one block group to another. You can also transfer objects among [[EM.Cube]]'s different modules. For example, you often need to move imported CAD models of terrain or buildings from CubeCAD to EM.Terrano. To transfer objects, first select them in the project workspace or select their names in the navigation tree. Then right-click on them and select <b>Move To → Module Name → Object Group</b> from the contextual menu. For example, if you want to move a selected object to a block group called "Terrain_1" in EM.Terrano, then you have to select the menu item '''Move To → EM.Terrano → Terrain_1''' as shown in the figure below. Note that you can transfer several objects altogether using the keyboards's {{key|Ctrl}} or {{key|Shift}} keys to make multiple selections.
In "Thin Wall Approximation", we assume that <table><tr><td> [[Image:PROP MAN3.png|thumb|left|720px|Moving the terrain model of Mount Whitney originally imported from an incident ray gives rise external digital elevation map (DEM) file to two rays, one is reflected at the specular point, and the other is transmitted almost EM.Terrano.]]</td></tr><tr><td>[[Image:PROP MAN4.png|thumb|left|720px|The imported terrain model of Mount Whitney shown in the same direction as the incident rayEM. The reflected ray is assumed to originate from Terrano's project workspace under a virtual image source point. Similar to the case of reflection and transmission at the interface between two dielectric media, here too we have three triplets of unit vectors, which all form orthonormal basis systemsterrain group called "Terrain_1".]]</td></tr></table>
[[File:thinwalltrans.png]]=== Adjustment of Block Elevation on Underlying Terrain Surfaces ===
The Incident In EM.Terrano, buildings and Transmitted Rays through all other geometric objects are initially drawn on the XY plane. In other words, the Z-coordinates of the local coordinate system (LCS) of all blocks are set to zero until you change them. Since the global ground is located a Thin Wallz = 0, your buildings are seated on the ground. When your propagation scene has an irregular terrain, you would want to place your buildings on the surface of the terrain and not buried under it. This can be done automatically as part of the definition of the block group. Open the property dialog of a block group and check the box labeled '''Adjust Block to Terrain Elevation'''. All the objects belonging to that block are automatically elevated in the Z direction such that their bases sit on the surface of their underlying terrain. In effect, the LCS of each of these individual objects is translated along the global Z-axis by the amount of the Z-elevation of the terrain object at the location of the LCS.
The transmission coefficients {{Note| You have to make sure that the resolution of your terrain, its variation scale and building dimensions are calculated for all comparable. Otherwise, on a rapidly varying high-resolution terrain, you will have buildings whose bottoms touch the two parallel terrain only at a few points and perpendicular polarizations as:parts of them hang in the air.}}
<table><tr><td> [[FileImage:frml20PROP MAN5.png|thumb|left|480px|The property dialog of impenetrable surface showing the terrain elevation adjustment box checked.]]</td></tr></table>
where<table><tr><td> [[Image:PROP MAN6.png|thumb|left|360px|A set of buildings on an undulating terrain without elevation adjustment.]]</td><td>[[Image:PROP MAN7.png|thumb|left|360px|The set of buildings on the undulating terrain after elevation adjustment.]]</td></tr></table>
[[File:frml21== EM.png]]Terrano's Ray Domain & Global Environment ==
=== Wedge Diffraction From Edges Why Do You Need a Finite Computational Domain? ===
For the purpose of calculation of diffraction from building edges, we define a "Wedge" as having two faces, the 0-face and the ''n''-face. The wedge angle is SBR simulation engine requires a = (2-''n'')p, where the parameter ''n'' is required finite computational domain for the calculation of diffraction coefficientsray termination. All the diffracted stray rays lie on that emanate from a cone with source inside this finite domain and hit its vertex at boundaries are terminated during the diffraction point simulation process. Such rays exit the computational domain and a wedge angle equal travel to the angle infinity, with no chance of incidence ever reaching any receiver in the opposite directionscene. A diffracted ray is assumed to originate from When you define a virtual image source pointpropagation scene with various elements like buildings, walls, terrain, etc. Three triplets of unit vectors are defined , a dynamic domain is automatically established and displayed as follows:a green wireframe box that surrounds the entire scene. Every time you create a new object, the domain box is automatically adjusted and extended to enclose all the objects in the scene.
* [[File:frml19_tn.png]] representing To change the unit vector normal to the edge and lying in the plane of the 0-faceray domain settings, follow the unit vector normal to the 0-face, and the unit vector along the edge, respectively.* [[Fileprocedure below:frml17_tn.png]] representing the incident forward polarization vector, incident backward polarization vector and incident propagation vector, respectively.* [[File:frml18_tn.png]] representing the diffracted forward polarization vector, diffracted backward polarization vector and diffracted propagation vector, respectively.
The three triplets constitute three orthonormal basis systems* Open the Ray Domain Settings Dialog by clicking the '''Domain''' [[File:image025. The propagation vector jpg]] button of the '''kSimulate Toolbar''', or by selecting ' ''Menu > Simulate > Computational Domain > Settings...''', or by right-clicking on the '''Ray Domain''' item of the diffracted ray has to be constructed based on navigation tree and selecting '''Domain Settings...''' from the diffraction cone contextual menu, or simply using the keyboard shortcut {{key|Ctrl+A}}.* The size of the Ray domain is specified in terms of six '''Offset''' parameters along the ±X, ±Y and ±Z directions. The default value of all these six offset parameters is 10 project units. Change these values as follows:you like.* You can also change the color of the domain box using the {{key|Color}} button.* After changing the settings, use the {{key|Apply}} button to make the changes effective while the dialog is still open.
<table><tr><td> [[FileImage:frml8PROP15.png|thumb|left|480px|EM.Terrano's domain settings dialog.]]</td></tr></table>
where === Understanding the resolution of the angle θ<sub>w</sub> is chosen to be the same as the resolution of the incident ray.Global Ground ===
[[File:diffractMost outdoor and indoor propagation scenes include a flat ground at their bottom, which bounces incident rays back into the scene. EM.Terrano provides a global flat ground at z = 0. The global ground indeed acts as an impenetrable surface that blocks the entire computational domain from the z = 0 plane downward. It is displayed as a translucent green plane at z = 0 extending downward. The color of the ground plane is always the same as the color of the ray domain. The global ground is assumed to be made of a homogeneous dielectric material with a specified permittivity ε<sub>r</sub> and electric conductivity σ. By default, a rocky ground is assumed with ε<sub>r</sub> = 5 and σ = 0.005 S/m. You can remove the global ground, in which case, you will have a free space scene. To disable the global ground, open up the "Global Ground Settings" dialog, which can be accessed by right clicking on the '''Global Ground''' item in the Navigation Tree and selecting '''Global Ground Settings... '''Remove the check mark from the box labeled '''"Include Half-Space Ground (z<0)"''' to disable the global ground. This will also remove the green translucent plane from the bottom of your scene. You can also change the material properties of the global ground and set new values for the permittivity and electric conductivity of the impenetrable, half-space, dielectric medium.png]]
The Incident Ray and Diffract Ray Cone at Alternatively, you can use EM.Terrano's '''Empirical Soil Model''' to define the Edge material properties of the global ground. This model requires a Buildingnumber of parameters: Temperature in °C, and Volumetric Water Content, Sand Content and Clay Content all as percentage.
The other unit vectors for the incident and diffracted rays are found as:{{Note|To model a free-space propagation scene, you have to disable EM.Terrano's default global ground.}}
<table><tr><td> [[FileImage:frml9Global environ.png|thumb|left|720px|EM.Terrano's Global Environment Settings dialog.]]</td></tr></table>
The diffraction coefficients are calculated in the following way:== Defining Point Transmitters & Point Receivers for Your Propagation Scene ==
[[File:frml11.png]]=== The Nature of Transmitters & Receivers ===
where In EM.Terrano, transmitters and receivers are indeed point radiators used for transmitting and receiving signals at different locations of the propagation scene. From a geometric point of view, both transmitters and receivers are represented by point objects or point arrays. These are grouped as base locations in the "Physical Structure" section of the navigation tree. As radiators, transmitters and receivers are defined by a radiator type with a certain far-field radiation pattern. Consistent with [[EM.Cube]]''Fs other computational modules, transmitters are categorizes as an excitation source, while receivers are categorized as a project observable. In other words, a transmitter is used to generate electromagnetic waves that propagate in the physical scene. A receiver, on the other hand, is used to compute the received fields and received signal power or signal-to-noise ratio (xSNR)'' is . For this reason, transmitters are defined and listed under the "Sources" sections of the navigation tree, while receivers are defined and listed under the Fresnel Transition function:"Observables" section.
[[File:frml12EM.png]]Terrano provides three radiator types for point transmitter sets:
In #Half-wave dipole oriented along one of the above equationsthree principal axes#Two collocated, we haveorthogonally polarized, isotropic radiators #User defined (arbitrary) antenna with imported far-field radiation pattern
[[File:frml10EM.png]]Terrano also provides three radiator types for point receiver sets:
[[File:frml13.png]]#Half-wave dipole oriented along one of the three principal axes#Polarization-matched isotropic radiator#User defined (arbitrary) antenna with imported far-field radiation pattern
where ''N<sup>±</sup>'' The default transmitter and receiver radiator types are the integers which most closely satisfy the equations 2''n''π''N<sup>±</sup>'' both vertical (Z- ν = ±πdirected) half-wave dipoles.
=== SBR As An Asymptotic EM Solver ===There are three different ways to define a transmitter set or a receiver set:
EM.Cube's SBR simulation engine can be used as a versatile *By defining point objects or point arrays under physical base location sets in the navigation tree and powerful asymptotic electromagnetic (EM) solver. If you compare EM.Cube's [[Propagation Module]] then associating them with its other computational modules, you will notice a lot of similarities. While other modules group objects primarily by their material propertiestransmitter or receiver set*Using Python commands emag_tx, [[Propagation Module]] categorizes the types of obstructing surfaces. Besides sharing the same ray-surface interaction mechanismsemag_rx, all the objects belonging to a surface group also share the same material properties. [[Propagation Module]] offers similar source types and similar observable types as the other computational modules. For instanceemag_tx_array, the Hertzian dipole sources used in a SBR simulation are identical to those offered in POemag_rx_array, MoM3D emag_tx_line and Planar modules. The plane wave sources are identical across all computational modules. [[Propagation Module]]'s sensor field planes, far field observables (either radiation patterns or RCS) and Huygens surfaces are all fully compatible with EM.Cube's other computational modules.emag_rx_line*Using the "Basic Link" wizard
As an asymptotic EM solver, the SBR engine can be used to model large-scale electromagnetic radiation and scattering problems. An example of this kind is radiation of simple or complex antennas === Defining a Point Transmitter Set in the presence of large scattering platforms. You have to keep in mind that by using an asymptotic technique in place of a full-wave method, you trade computational speed and lower memory requirements for modeling accuracy. In particular, the SBR method cannot take into account the electromagnetic coupling effects among nearby radiators or scatterers. However, when your scene spans thousands of wavelengths, an SBR simulation might often prove to be your sole practical solution. Formal Way ===
=== Novelties Of Transmitters act as sources in a propagation scene. A transmitter is a point radiator with a fully polarimetric radiation pattern defined over the entire 3D space in the standard spherical coordinate system. EM.Cube's SBR Solver ===Terrano gives you three options for the radiator associated with a point transmitter:
EM.Cube's new SBR simulation engine utilizes an intelligent ray tracing algorithm based on the concept of k* Half-dimensional trees. A k-d tree is a space-partitioning data structure for organizing points in a k-dimensional space. k-d trees are particularly useful for searches that involve multidimensional search keys such as range searches and nearest neighbor searches. In a typical large radio propagation scene, there might be a large number of rays emanating from the transmitter that may never hit any obstacles. For example, upward-looking rays in an urban propagation scene quickly exit the computational domain. Rays that hit obstacles on their path, on the other hand, generate new reflected and transmitted rays. The k-d tree algorithm traces all these rays systematically in a very fast and efficient manner. Another major advantage of k-d trees is the fast processing of multi-transmitters scenes. Unlike the previous versions of the SBR solver which could handle one transmitter at a time and would superpose all the resulting rays at the end of the simulation, the new SBR shoots rays from all the transmitters at the same time. wave dipole* Orthogonally polarized isotropic radiators* User defined antenna pattern
By default, EM.Cube's new SBR simulation engine performs fully polarimetric and coherent SBR simulations with arbitrary Terrano assumes that your transmitter is a vertically polarized (Z-directed) resonant half-wave dipole antenna patterns. The new engine solves directly for the vectorial field components at the receiver locations or field observation pointsThis antenna has an almost omni-directional radiation pattern in all azimuth directions. This is far more rigorous than It also has radiation nulls along the previous versions axis of the SBR solver which primarily utilized ray power calculations based on the two vertical and horizontal polarizationsdipole. In other words, EM.Cube's new SBR engine is a truly asymptotic "field" solver. As a result, you You can visualize change the magnitude and phase direction of all six electric the dipole and magnetic field components at any point in orient it along the computational domainX or Y axes using the provided drop-down list. For power calculations at the receiver location, an The second choice of two orthogonally polarized isotropic, polarization-matched, receiving antenna radiators is assumedan abstract source that is used for polarimetric channel characterization as will be discussed later.
In most scenes, You can override the buildings default radiator option and the ground or terrain can be assumed to be made select any other kind of homogeneous materialsantenna with a more complicated radiation pattern. These are represented by their electrical properties such as permittivity e and electric conductivity For this purpose, you have to import a radiation pattern data file to EM.Terrano. You can model any radiating structure using [[EM.Cube]]'sother computational modules, [[EM. More complex scenes may involve a multilayer ground or multilayer building wallsTempo]], [[EM. In such casesPicasso]], one can no longer use the simple reflection [[EM.Libera]] or transmission coefficient formulas [[EM.Illumina]], and generate a 3D radiation pattern data file for homogeneous medium interfacesit. EMThe far-field radiation patter data are stored in a specially formatted file with a "'''.Cube calculates the reflection and transmission coefficients RAD'''" file extension. This file contains columns of multilayer structures spherical φ and θ angles as functions well as the real and imaginary parts of incident angle, frequency the complex-valued far-zone electric field components '''E<sub>θ</sub>''' and polarization '''E<sub>φ</sub>'''. The θ- and uses them at φ-components of the far-zone electric field determine the polarization of the respective specular pointstransmitting radiator.
=== Limitations of {{Note|By default, EM.Cube's SBR Solver ===Terrano assumes a vertical half-wave dipole radiator for your point transmitter set.}}
It is very important A transmitter set always needs to keep be associated with an existing base location set with one or more point objects in mind that SBR is an asymptotic electromagnetic analysis technique that is based on Geometrical Optics (GO) and the Uniform Theory of Diffraction (UTD)project workspace. It is not a "full-wave" techniqueTherefore, and it does not solve Maxwell's equations directly or numerically. SBR makes you cannot define a number of assumptions, chief among them, transmitter for your scene before drawing a very high operational frequency such that the length scales involved are much larger than the operating wavelength. Under this assumed regime, electromagnetic waves start to behave like optical rays. Virtually all the calculations in SBR are based on far field approximationspoint object under a base location set.
In order [[Image:Info_icon.png|40px]] Click here to maintain learn how to define a high computational speed for urban propagation problems, EM.Cube's SBR solver ignores double diffractions. Recall that diffractions from edges give rise to a large number of new secondary rays. The power of diffracted rays drops much faster than reflected rays. EM''[[Glossary_of_EM.Cube ignores diffracted rays that are not detected by any receiver. In other words%27s_Materials, an edge-diffracted ray does not diffract again from another edge. However_Sources, reflected and penetrated rays do get diffracted from edges just as rays emanated directly from the sources do_Devices_%26_Other_Physical_Object_Types#Point_Transmitter_Set | Point Transmitter Set]]'''.
== Anatomy Of A Propagation Scene ==<table><tr><td> [[Image:Terrano L1 Fig11.png|thumb|left|480px|The point transmitter set definition dialog.]] </td></tr></table>
An EM.Cube propagation scene typically consists of several elements. At a minimum, Once you need define a new transmitter (Tx) at some location to launch rays into set, its name is added in the scene '''Transmitters''' section of the navigation tree. The color of all the base points associated with the newly defined transmitter set changes, and a receiver an additional little ball with the transmitter color (Rxred by default) appears at another location to receive and collect the incoming rayslocation of each associated base point. A You can open the property dialog of the transmitter set and modify a receiver together make the simplest propagation scene, representing a free-space line-number of-sight (LOS) channelparameters including the '''Source Power''' in Watts and the broadcast signal '''Phase''' in degrees. A The default transmitter power level is one of EM1W or 30dBm.CubeThere is also a check box labeled '''Use Custom Input Power'''s several source types, while a receiver which is one of checked by default. In that case, the power and phase boxes are enabled and you can change the default 1W power and 0° phase values as you wish. [[EM.Cube]]'s several observable types". A simpler source type is a Hertzian dipoleRAD" radiation pattern files usually contain the value of "Total Radiated Power" in their file header. A simpler observable This quantity is a field sensor calculated based on the particular excitation mechanism that is was used to compute generate the electric and magnetic fields on a specified planepattern file in the original [[EM.Cube]] module. When the "Use Custom Input Power" check box is unchecked, EM.Terrano will use the total radiated power value of the radiation file for the SBR simulation.
An outdoor propagation scene may involve several buildings (modeled as impenetrable surfaces) and an underlying flat ground or irregular terrain surface. An indoor propagation scene may involve several walls (modeled as thin penetrable surfaces), a ceiling and a floor arranged according {{Note|In order to a certain floor plan. You can also build mixed scenes involving both impenetrable and penetrable blocks, possibly along with irregular terrain surfaces. Your sources and observables can be placed anywhere in the scene. Your transmitters and receivers can be placed outdoors or indoors. A complete list modify any of the various elements of a propagation scene is given in the '''Physical Structure''' section of [[Propagation Module]]transmitter set's Navigation Tree parameters, first you need to select the "User Defined Antenna" option, even if you want to keep the vertical half-wave dipole as follows:your radiator.}}
* Impenetrable Surfaces<table>* Penetrable Surfaces<tr>* Terrain Surfaces<td> * Base Points[[File:NewTxProp.png|thumb|left|720px|The property dialog of a point transmitter set.]]</td></tr></table>
ImpenetrableYour transmitter in EM.Teranno is indeed more sophisticated than a simple radiator. It consists of a basic "Transmitter Chain" that contains a voltage source with a series source resistance, penetrable and terrain surfaces all obstruct the propagation connected via a segment of electromagnetic waves (rays) in transmission line to a transmit antenna, which is used to launch the broadcast signal into the free space. What differentiates them is The transmitter's property dialog allows you to define the basic transmitter chain. Click the types {{key|Transmitter Chain}} button of physical phenomena the Transmitter Set dialog to open the transmitter chain dialog. As shown in the figure below, you can specify the characteristics of the baseband/IF amplifier, mixer and power amplifier (PA) including stage gains and impedance mismatch factors (IMF) as well as the characteristics of the transmission line segment that are used connects the PA to model their interaction with the impinging raysantenna. Base points Note that the transmit antenna characteristics are simply used to define automatically filled using the contents of the imported radiation pattern data file. The transmitter Chain dialog also calculates and receiver locations in reports the scene"Total Transmitter Chain Gain" based on your input. The following sections of When you close this manual dialog and return to the Transmitter Set dialog, you will describe each see the calculated value of these elements the Effective Isotropic Radiated Power (EIRP) of your transmitter in detaildBm.
{{Note| If you do not modify the default parameters of the transmitter chain, a 50-Ω conjugate match condition is assumed and the power delivered to the antenna will be -3dB lower than your specified baseband power.}} <table><tr><td> [[File:PROP14(1)NewTxChain.png|thumb|left|720px|EM.Terrano's point transmitter chain dialog.]]</td></tr></table>
Figure 1: The Navigation Tree of EM.Cube's [[Propagation Module]].=== Defining a Point Receiver Set in the Formal Way ===
=== Receivers act as observables in a propagation scene. The Various Types Of Surfaces & Blocks ===objective of a SBR simulation is to calculate the far-zone electric fields and the total received power at the location of a receiver. You need to define at least one receiver in the scene before you can run a SBR simulation. Similar to a transmitter, a receiver is a point radiator, too. EM.Terrano gives you three options for the radiator associated with a point receiver set:
In a SBR simulation, the propagating rays hit the surface of building structures, walls, terrain (or global ground) and bounce back into the scene (reflection). Some rays penetrate thin walls or other penetrable surfaces and continue their path on the other side of the surface (transmission). The field intensity, phase and power of the reflected and transmitted rays depend on the material properties of the obstructing surface. The specular surface can be modeled as a simple homogeneous dielectric half* Half-space or as a multilayer structure. In that respect, the buildings, walls, terrain or even the global ground all behave in a similar way:wave dipole* Polarization matched isotropic radiator* User defined antenna pattern
* They terminate an impinging ray By default, EM.Terrano assumes that your receiver is a vertically polarized (Z-directed) resonant half-wave dipole antenna. You can change the direction of the dipole and replace orient it with one along the X or more new raysY axes using the provided drop-down list.* They represent An isotropic radiator has a specular interface between two media of different material compositions for calculating perfect omni-directional radiation pattern in all azimuth and elevation directions. An isotropic radiator doesn't exist physically in the reflectionreal world, transmission and possibly diffraction coefficientsbut it can be used simply as a point in space to compute the electric field.
EMYou may also define a complicated radiation pattern for your receiver set.Cube has generalized the concept of '''Block''' as any object In that obstructs and affects radio wave propagation. Rays hit the facets of case, you need to import a block and bounce off the surface of those facets or penetrate them and continue their propagation. Rays also get diffracted off the edges of these blocks. In radiation pattern data file to EM.Cube's [[Propagation Module]], blocks are grouped together by Terrano similar to the type case of their interaction with raysa transmitter set. EM.Cube currently offers three types of blocks for use in a propagation scene:
# '''Impenetrable Surfaces:''' Rays hit the facets of this type of blocks and bounce back{{Note|By default, but they do not penetrate the objectEM. It is assumed that the interior of such blocks or buildings are highly absorptive.# '''Penetrable Surfaces:''' These blocks represent thin surfaces that are used to model the exterior and interior walls of buildings based on the "Thin Wall Approximation". Rays reflect off the surface of penetrable surfaces and diffract off their edges. They also penetrate such thin surfaces and continue their paths on the other side of the wall.# '''Terrain Surfaces:''' These blocks are used to provide one or more impenetrable, ground surfaces for the propagation scene. Rays simply bounce off terrain objects. The global ground acts as Terrano assumes a flat supervertical half-terrain that covers the bottom of the entire computational domainwave dipole radiator for your point receiver set. }}
EM.Cube's [[Propagation Module]] allows you Similar to transmitter sets, you define block groups of each of the above three types. Each block group has the same color a receiver set by associating it with an existing base location set with one or texture and its members share more point objects in the same material properties: permittivity e<sub>r</sub> and conductivity sproject workspace. Also, all All the penetrable surfaces receivers belonging to the same block group receiver set have the same wall thicknessradiator type. You can A typical propagation scene contains one or few transmitters but usually a large number of receivers. To generate a wireless coverage map, you need to define many different block groups with certain properties and underneath each introduce many member objects with different geometrical shapes and dimensionsan array of points as your base location set. The table below summarizes the characteristics of each block type:
{[[Image:Info_icon.png| class="wikitable"40px]] Click here to learn how to define a '''[[Glossary_of_EM.Cube%27s_Simulation_Observables_%26_Graph_Types#Point_Receiver_Set |-! scope="col"| Block Type! scope="col"|Physical Effects! scope="col"|Admissible Object Types|-| Impenetrable Surface| Reflection, Diffraction| All Solid & Surface CAD Objects|-| Penetrable Surface| Reflection, Diffraction, Transmission| All Solid & Surface CAD Objects|-| Terrain Surface| Reflection| Tessellated Objects Only|}Point Receiver Set]]'''.
=== Impenetrable Surfaces For Outdoor Scenes ===<table><tr><td> [[Image:Terrano L1 Fig12.png|thumb|left|480px|The point receiver set definition dialog.]] </td></tr></table>
In outdoor propagation scenes such as "Urban Canyons"Once you define a new receiver set, you are primarily interested in its name is added to the wireless coverage in '''Receivers''' section of the areas among buildingsnavigation tree. You can assume that rays bounce off The color of all the exterior walls of these buildings but do not penetrate them. In other wordsbase points associated with the newly defined receiver set changes, you ignore the transmitted rays and assume that they are either absorbed or diffused inside an additional little ball with the buildings. This is not an unrealistic assumption. EM.Cube offers "Impenetrable Blocks" to model buildings in outdoor propagation scenes. A penetrable block has a receiver color or texture property as well as material properties: permittivity (e<sub>r</sub>yellow by default) appears at the location of each associated base point. You can open the property dialog of the receiver set and conductivity (s). By default, modify a brick building is assumed with e<sub>r</sub> = 4.4 and s = 0.001S/m. Impinging rays are reflected from the facets number of impenetrable buildings or diffracted from their edgesparameters.
To define a new impenetrable block group, follow these steps<table><tr><td> [[File:NewRxProp.png|thumb|left|720px|The property dialog of a point receiver set.]]</td></tr></table>
# Right click on either In the '''Impenetrable Surfaces''' item of the Navigation Tree and select '''Insert New Block...''' A Receiver Set dialog for setting up the block properties opens up offering , there is a preloaded material type (Brick) with predefined color and texture.# Specify a name for the block group and select a color or texture.# The electromagnetic model that determines raydrop-block interaction is selected under down list labeled '''Specular Interface TypeSelected Element'''. Two options are available: '''Standard Material''' or '''User Defined Model'''. The former is the default choice and requires material properties, '''Permittivity''' (e<sub>r</sub>) and '''Electric Conductivity''' (s), which are contains a list of all the individual receivers belonging to the receiver set to "Brick" by default. No magnetic properties are allowed for blocks.# Click At the '''OK''' button end of an SBR simulation, the button labeled {{key|Show Ray Data}} becomes enabled. Clicking this button opens the Ray Data dialog to accept , where you can see a list of all the changes received rays at the selected receiver and close ittheir computed characteristics.
[[File:PROP14If you choose the "user defined antenna" option for your receiver set, it indeed consists of a basic "Receiver Chain" that contains a receive antenna connected via a segment of transmission line to the low-noise amplifier (2LNA)that is terminated in a matched load.png]] The receiver set's property dialog allows you to define the basic receiver chain. Click the {{key|Receiver Chain}} button of the Receiver Set dialog to open the receiver chain dialog. As shown in the figure below, you can specify the characteristics of the LNA such as its gain and noise figure in dB as well as the characteristics of the transmission line segment that connects the antenna to the LNA. Note that the receiving antenna characteristics are automatically filled from using contents of the radiation file. You have to enter values for antenna's '''Brightness Temperature''' as well as the temperature of the transmission line and the receiver's ambient temperature. The effective '''Receiver Bandwidth''' is assumed to be 100MHz, which you can change for the purpose of noise calculations. The Receive Chain dialog calculates and reports the "Noise Power" and "Total Receiver Chain Gain" based on your input. At the end of an SBR simulation, the receiver power and signal-noise ratio (SNR) of the selected receiver are calculated and they are reported in the receiver set dialog in dBm and dB, respectively. You can examine the properties of all the individual receivers and all the individual rays received by each receiver in your receiver set using the "Selected Element" drop-down list.
Figure 1: <table><tr><td> [[Propagation Module]]File:NewRxChain.png|thumb|left|720px|EM.Terrano's Impenetrable Surface point receiver chain dialog.]] </td></tr></table>
Under an impenetrable block group, you can draw any of EM.Cube's native solid or surface objects or you can import external model files like STEP, IGES or STL. You can change the properties of an impenetrable surface. In the property dialog of the surface group, click on the table that list the properties to select === Modulation Waveform and highlight a row. Then, click the '''Add/Edit''' button to open up the "Edit Layer" dialog. In this dialog, you can change the name of the material and its permittivity and electric conductivity. The box labeled "Specify Loss Tangent" is unchecked by default. If you check it, you can specify the '''Loss Tangent''' of the material, which, in turn, updates the value of electric conductivity at the center frequency of the project. You can also use EM.Cube's Material List, which will be explained later. Detection ===
[[File:PROP23EM.png]]Terrano allows you to define a digital modulation scheme for your communication link. There are currently 17 waveforms to choose from in the receiver set property dialog:
Figure 2: [[Propagation Module]]'s "Edit Layer" dialog corresponding to impenetrable surfaces*OOK*M-ary ASK*Coherent BFSK*Coherent QFSK*Coherent M-ary FSK*Non-Coherent BFSK*Non-Coherent QFSK*Non-Coherent M-ary FSK*BPSK*QPSK*Offset QPSK*M-ary PSK*DBPSK*pi/4 Gray-Coded DQPSK*M-ary QAM*MSK*GMSK (BT = 0.3)
=== Penetrable Surfaces For Indoor Scenes ===In the above list, you need to specify the '''No. Levels (M)''' for the Mary modulation schemes, from which the '''No. Bits per Symbol''' is determined. You can also define a bandwidth for the signal, which has a default value of 100MHz. Once the SNR of the signal is found, given the specified modulation scheme, the E<sub>b</sub>/N<sub>0</sub> parameter is determined, from which the bit error rate (BER) is calculated.
A typical indoor propagation scene usually involves an arrangement of walls that represent the interior of a building. The transmitters and receivers are then placed in the spaces among such walls. From the point of view of EM.Cube's SBR simulator, walls act like thin penetrable surfaces. EM.Cube uses the "Thin Wall Approximation" to model penetrable surfaces. It assumes that rays simply penetrate a wall and exit at the same specular point on the opposite side of the wall. In other words, rays are not displaced by the walls, nor do they get trapped inside the walls (no internal reflection). This is equivalent to assuming a zero thickness for penetrable surfaces for the purpose of geometrical ray tracing, while the finite thickness of the "thin" surface is used for electromagnetic calculation of transmission coefficient. EM.Cube offers "Penetrable Surface Blocks" for Shannon â Hartley Equation estimates the construction of rooms in indoor propagation scenes as well as modeling of hollow buildings and other structures. You can define many penetrable surface groups with arbitrary thicknesses and material properties (color, texture, permittivity and electric conductivity).channel capacity:
To define a new penetrable surface group, follow these steps:<math> C = B \log_2 \left( 1 + \frac{S}{N} \right) </math>
# Right click on one of where B in the '''Penetrable Surfaces''' item bandwidth in the Navigation Tree Hz, and select '''Insert New Block...''' A dialog for setting up C is the wall properties opens up offering a preloaded material type channel capacity (Brickmaximum data rate) with predefined color and texture.# Specify a name for the surface group and select a color or texture.# The properties of a penetrable surface are identical to those of an impenetrable surface, plus an additional thickness property.# By default, a brick wall with a thickness of 0.5 units is assumed. You can change the '''Thickness''' of the penetrable surface as well as its '''Permittivity''' e<sub>r<expressed in bits/sub> and '''Electric Conductivity''' s.# Click the '''OK''' button of the dialog to accept the changes and close it.
[[File:PROP15(1).png]]The spectral efficiency of the channel is defined as
Figure <math> \eta = \log_2 \left( 1: [[Propagation Module]]'s Penetrable Surface dialog.+ \frac{S}{N} \right) </math>
Under a penetrable surface group, you can draw any of EM.Cube's native solid or surface objects or you can import external model files like STEP, IGES or STL. You can change The quantity E<sub>b</sub>/N<sub>0</sub> is the properties ratio of a penetrable surface group including its default thicknessenergy per bit to noise power spectral density. In the property dialog of the surface group, click on the table that list the properties to select and highlight It is a row. Then, click the '''Add/Edit''' button to open up the "Edit Layer" dialog. Similar to the case measure of impenetrable surfaces, from this dialog, you can change the material properties (permittivity SNR per bit and electric conductivity) as well as '''Thickness''', which is expressed in calculated from the project units. You can also use EM.Cube's Material List, which will be explained later.following equation:
[[File:PROP25.png]]<math> \frac{E_b}{N_0} = \frac{ 2^\eta - 1}{\eta} </math>
Figure 2: [[Propagation Module]]'s where "eta;Edit Layer" dialog corresponding to penetrable surfacesis the spectral efficiency.
You can construct several thin walls The relationship between the bit error rate and arrange them as rooms. A regular room can be built by placing four vertical wall objects together with an optional horizontal wall at E<sub>b</sub>/N<sub>0</sub> depends on the top for the ceilingmodulation scheme and detection type (coherent vs. Alternatively, you may use EM.Cube's hollow box objects or boxes with one or two capped end(snon-coherent). '''Keep in mind that all the penetrable surfaces belonging to a group have the same wall thicknessFor example, which is initially set to 0.5 project units by default. Alsofor coherent QPSK modulation, note that solid CAD objects belonging to a penetrable surface group are treated as air-filled hollow structures.''' The thickness of penetrable surfaces is implied and not visualized when displaying objects in the project workspace.one can write:
<math> P_b === Computational Domain &0.5 \; Global Ground ===\text{erfc} \left( \sqrt{ \frac{E_b}{N_0} } \right) </math> where P<sub>b</sub> is the bit error rate and erfc(x) is the complementary error function:
The SBR simulation engine requires a finite computational domain. All the stray rays that hit the boundaries of this finite domain are terminated during the simulation process. Such rays exit the computational domain and travel to the infinity, with no chance of ever reaching any receiver in the scene. When you define a propagation scene with various elements like buildings, walls, terrain, etc., a dynamic domain is automatically established and displayed as a wireframe box with green lines that surrounds the entire scene. Every time you create a new object, the domain is automatically adjusted and extended to enclose all the objects in the scene. You can change the size and color of the domain box through the Ray Domain Settings Dialog, which can be accessed in one of the following three ways:<math> \text{erfc}(x) = 1-\text{erf}(x) = \frac{2}{\sqrt{\pi}} \int_{x}^{\infty} e^{-t^2} dt </math>
# Click the The '''DomainMinimum Required SNR''' [[File:image025parameter is used to determine link connectivity between each transmitter and receiver pair.jpg]] button of the Simulation Toolbar.# Select If you check the box labeled '''SimulateGenerate Connectivity Map''' > '''Computational Domain''' > '''Settings...''' item in the receiver set property dialog, a binary map of the Simulate Menupropagation scene is generated by EM.# Right click Terrano, in which one color represents a closed link and another represent no connection depending on the '''Ray Domain''' item selected color map type of the Navigation Tree and select '''Domain Settingsgraph.EM..'''# Use Terrano also calculates the keyboard shortcut '''Ctrl + AMax Permissible BER'''corresponding to the specified minimum required SNR and displays it in the receiver set property dialog.
The size of the Ray domain is specified in terms of six '''Offset''' parameters along the ±X, ±Y and ±Z directions=== A Note on EM. The default value of all these six offset parameters is 10 project units. You can change them arbitrarily. After changing these values, use the Terrano'''Apply''' button to make the changes effective while the dialog is still open.s Native Dipole Radiators ===
[[File:PROP15When you define a new transmitter set or a new receiver set, EM.png]]Terrano assigns a vertically polarized half-wave dipole radiator to the set by default. The radiation pattern of this native dipole radiators is calculated using well-know expressions that are derived based on certain assumptions and approximations. For example, the far-zone electric field of a vertically-polarized dipole antenna can be expressed as:
Figure 1: <math> E_\theta(\theta,\phi) \approx j\eta_0 I_0 \frac{e^{-jk_0 r}}{2\pi r} \left[[Propagation Module]\frac{\text{cos} \left( \frac{k_0 L}{2} \text{cos} \theta \right) - \text{cos} \left( \frac{k_0 L}{2} \right) }{\text{sin}\theta} \right]'s Domain Settings dialog. </math>
Most outdoor and indoor propagation scenes include a flat ground at their bottom, which bounces incident rays back into the scene. EM.Cube's [[Propagation Module]] provides a global flat ground at z = 0. The global ground indeed acts as an impenetrable surface that blocks the entire computational domain from the z = 0 plane downward. It is displayed as a translucent green plane at z = 0 extending downward. The color of the ground plane is always the same as the color of the ray domain. The global ground is assumed to be made of a homogeneous dielectric material with a specified permittivity e<submath>r</sub> and electric conductivity s. By defaultE_\phi(\theta, a rocky ground is assumed with e<sub>r\phi) \approx 0 </submath> = 5 and s = 0.005 S/m. You can remove the global ground, in which case, you will have a free space scene. To disable the global ground, open up the Global Ground Settings Dialog, which can be accessed by right clicking on the '''Global Ground''' item in the Navigation Tree and selecting '''Global Ground Settings... '''Remove the check mark from the box labeled '''"Include Half-Space Ground (z<0)"''' to disable the global ground. This will also remove the green translucent plane from the bottom of your scene. You can also change the material properties of the global ground and set new values for the permittivity and electric conductivity of the impenetrable, half-space, dielectric medium. '''Do not forget to disable the global ground if you want to model a free space propagation scene.'''
[[File:PROP4where k<sub>0</sub> = 2π/λ<sub>0</sub> is the free-space wavenumber, λ<sub>0</sub> is the free-space wavelength, η<sub>0</sub> = 120π Ω is the free-space intrinsic impedance, I<sub>0</sub> is the current on the dipole, and L is the length of the dipole.png]]
Figure 2The directivity of the dipole antenna is given be the expression: [[Propagation Module]]'s Global Ground Settings dialog.
=== Terrain Surfaces vs. Global Ground ===<math> D_0 \approx \frac{2}{F_1(k_0L) + F_2(k_0L) + F_3(k_0L)} \left[ \frac{\text{cos} \left( \frac{k_0 L}{2} \text{cos} \theta \right) - \text{cos} \left( \frac{k_0 L}{2} \right) }{\text{sin}\theta} \right]^2 </math>
A terrain surface acts as a custom, unlevel or irregular ground for your propagation scene. EM.Cube's default global ground blocks the z < 0 half-space everywhere in the computational domain. You can simply turn off the global ground and create one or more terrain objects and place them arbitrarily in the scene. You can also import an external terrain model or file. A terrain represents an impenetrable surface with a more complex surface profile. You can have one or more terrain objects of finite extents and place them on or above the global ground.
Terrain objects have some important differences with objects of the "Impenetrable Surface" type:<math> F_1(x) = \gamma + \text{ln}(x) - C_i(x) </math>
# While impenetrable blocks can be created using any of EM.Cube's solid or surface CAD object creation tools, terrain objects are created either using EM.Cube's '''Terrain Generator''' or by importing an external terrain file. # Terrain objects belong to a special type of CAD objects called "Tessellated Objects", which differ from other regular CAD surface objects or EM.Cube's polymesh surfaces.# Terrain surfaces do not diffract impinging rays at their many small edges.# Terrain objects affect the elevation of other objects or transmitters or receivers that are located above them.<math> F_2(x) = \frac{1}{2} \text{sin}(x) \left[ S_i(2x) - 2S_i(x) \right] </math>
Just as other blocks are grouped by their color, texture and material composition, terrain objects are also grouped in a similar fashion. Before you can generate or import a new terrain object, first you have to define a terrain group and specify its color<math> F_3(x) = \frac{1}{2} \text{cos}(x) \left[ \gamma + \text{ln}(x/texture and material properties. To define a new terrain group, follow these steps:2) + C_i(2x) - 2C_i(x) \right] </math>
* Right click on the '''Terrain''' item in the Navigation Tree and select '''Insert New Terrain...''' A dialog for setting up the terrain properties opens up offering a of preloaded material type (Rock) with predefined green color and no texture.
* Specify a name for the terrain group and select a color or texture.
* Similar to other blocks, you have to specify the material properties, Permittivity (e<sub>r</sub>) and Electric Conductivity (s), of the terrain group. Rock with e<sub>r</sub> = 5 and s = 0.005S/m is the default material choice for a new terrain.
* Click the '''OK''' button of the dialog to accept the changes and close it.
[[File:PROP16where γ = 0.png]]5772 is the Euler-Mascheroni constant, and C<sub>i</sub>(x) and S<sub>i</sub>(x) are the cosine and sine integrals, respectively:
Figure 1: [[Propagation Module]]'s Terrain dialog.
You can change the properties of a terrain surface group from its property dialog. Click on the table that list the properties to select and highlight a row. Then, click the '''Add<math> C_i(x) = - \int_{x}^{\infty} \frac{ \text{cos} \tau}{\tau} d\tau </Edit''' button to open up the "Edit Layer" dialog, which is identical to the case of impenetrable surfaces. You can also use EM.Cube's Material List, which will be explained later. When a new terrain type is created, its node on the Navigation Tree becomes active. Under this node you can create and add new terrain objects. When a terrain node is active for drawing, all CAD object creation tools are disabled. You have three options for creating a new terrain object, which will be described in detail in the next sections of this manual:math>
# Use EM.Cube's '''Terrain Generator'''.# Import an external terrain file of "'''.TRN'''" type.# Import an external terrain file of "'''.DEM'''" type.<math> S_i(x) = \int_{0}^{x} \frac{ \text{sin} \tau}{\tau} d\tau </math>
=== Using Terrain Generator ===
EM.Cube provides In the case of a convenient half-wave dipole, L = λ<sub>0</sub>/2, and powerful Terrain Generator for creating a variety D<sub>0</sub> = 1.643. Moreover, the input impedance of terrain surface objectsthe dipole antenna is Z<sub>A</sub> = 73 + j42. EM5 Ω.Cube's Terrain Generator looks very similar These dipole radiators are connected via 50Ω transmission lines to CubeCAD's Surface Generator. However, whereas the Surface Generator creates a generic 50Ω source or polymesh surface objectload. Therefore, Terrain Generator there is always creates another special type of object known as a '''Tessellated Object'''. A terrain object is much simpler than EM.Cube's polymesh objects and is usually made up certain level of triangular or quadrilateral facetsimpedance mismatch that violates the conjugate match condition for maximum power. As such, terrain objects have limited editing capabilities. For example, you can cut, copy, paste, translate or rotate terrain objects. But operations like scaling, mirroring, grouping (composite), arraying, exploding, linking or Boolean operations do not work on terrain objects.
To create a new terrain object using Terrain Generator, first you need to define a terrain group in the Navigation Tree. Right click on the name of the terrain node and select '''Terrain Generator.<table><tr><td> [[File:Dipole radiators.png|thumb|720px|EM.Terrano''' from the contextual menus native half-wave dipole transmitter and receiver. This opens up the Terrain Generator Dialog. Using Terrain Generator, you can build a single terrain surface or an array of surfaces patched together. Some of the available terrain models include:]] </td></tr></table>
# Flat Plane# Hill On the other hand, we you specify a user-defined antenna pattern for the transmitter or receiver sets, you import a 3D radiation pattern file that contains all the values of E<sub>θ</sub> and E<sub>φ</sub> for all the combinations of (Elliptic Quadraticθ, φ)# Mountain (Elliptic Cone)# 1angles. Besides the three native dipole radiators, [[EM.Cube]] also provides 3D radiation pattern files for three X-, Y-D and 2Z-polarized half-D Cliff# Gaussian Hump# Undulated Sinusoid# Undulated Sinc# Superwave resonant dipole antennas. These pattern data were generated using a full-quadratic Plateau# Custom Function# XY Grid Datawave solver like [[EM.Libera]]'s wire MOM solver. The names of the radiation pattern files are:
In all of the above models, you can set the height of the surface object to an any desired value* DPL_STD_X. You set the lateral extents of the surface and its resolution along the X and Y directions in the boxes labeled '''Range Start''', '''Range Stop''' and '''Range Step'''RAD* DPL_STD_Y. The step values along the X and Y directions are a measure of surface smoothness: the smaller the step values, the higher the resolution and the smoother the resulting terrain objectRAD* DPL_STD_Z.RAD
[[File:PROP18and they are located in the folder "\Documents\EMAG\Models" on your computer. Note that these are full-wave simulation data and do not involve any approximate assumptions. To use these files as an alternative to the native dipole radiators, you need to select the '''User Defined Antenna Pattern''' radio button as the the radiator type in the transmitter or receiver set property dialog.png]]
Figure: [[Propagation Module]]'s Terrain Generator dialog.=== A Note on the Rotation of Antenna Radiation Patterns ===
Some surface types have EM.Terrano's Transmitter Set dialog and Receiver Set dialog both allow you to rotate an additional shape factor called imported radiation pattern. In that case, you need to specify the '''AlphaRotation''' that angles in degrees about the X-, Y- and Z-axes. It is identical important to the alpha parameter note that these rotations are performed sequentially and in the surface generator. For examplefollowing order: first a rotation about the X-axis, then a Gaussian Hump is defined as exprotation about the Y-axis, and finally a rotation about the Z-axis. In addition, all the rotations are performed with respect to the "rotated" local coordinate systems (LCS). In other words, the first rotation with respect to the local X-raxis transforms the XYZ LCS to a new primed X<sup>2′</sup>Y<sup>′</(2asup>Z<sup>2′</sup>)), where r is the polar radiusLCS. For a Super-quadratic Hump, the input parameter a defines the degree of the super-quadratic surface. a = 2 corresponds to an ellipsoid. Larger values of a get close to a rectangular base with rounded corners. An undulated sinusoidal surface The second rotation is defined by cos(pax/Dperformed with respect to the new Y<subsup>x′</subsup>)*cos(pay/D-axis and transforms the X<subsup>y′</subsup>), and an undulated sinc is defined by DY<subsup>x′</subsup>*DZ<subsup>y′</subsup>*sin(pax/DLCS to a new double-primed X<subsup>x′′</subsup>)*sin(pay/DY<subsup>x′′</subsup>)/(2pxy), where DZ<subsup>x′′</subsup> and DLCS. The third rotation is finally performed with respect to the new Z<subsup>y′′</subsup> are the X and Y dimensions, respectively. Terrain Generator creates a unit cell based on the specified surface type-axis. From the same dialog, you can also produce an array arrangement of such unit cells. Simply enter any number of elements along the X The figures below shows single and Y directions in the boxes labeled '''Array'''double rotations.
<table><tr><td> [[File:PROP19PROP22B.png|800pxthumb|300px|The local coordinate system of a linear dipole antenna.]] </td><td> [[File:PROP22C.png|thumb|600px|Rotating the dipole antenna by +90° about the local Y-axis.]] </td></tr></table><table><tr><td> [[File:PROP22D.png|thumb|720px|Rotating the dipole antenna by +90° about the local X-axis and then by -45° by the local Y-axis.]] </td></tr></table>
Figure: A 4 Ã 4 array === Adjustment of hill terrain objects.Tx/Rx Elevation above a Terrain Surface ===
You can define any arbitrary surface by entering an equation of When your transmitters or receivers are located above a flat terrain like the two [[variables]] x and y global ground, their Z-coordinates are equal to their height above the ground, as z = f(xthe terrain elevation is fixed and equal to zero everywhere. In many propagation modeling problems,y)your transmitters and receivers may be located above an irregular terrain with varying elevation across the scene. In this that case, you have may want to select the '''Custom Function''' option in the dropdown list labeled '''Model'''. You should enter place your equation as any mathematical expression in transmitters or receivers at a certain height above the box labeled '''Function f(x,y)'''underlying ground. You can use any The Z-coordinate of EM.Cube's mathematical functions listed in the '''Function Dialog''' a transmitter or combine several receiver is now the sum of themthe terrain elevation at the base point and the specified height. Note that after selecting EM.Terrano gives you the custom function option, to adjust the height of transmitter and receiver sets to the surface terrain elevation. This is determined by your equation, done for individual transmitter sets and individual receiver sets. At the top of the Transmitter Dialog there is a check box labeled "'''HeightAdjust Tx Sets to Terrain Elevation''' box ". Similarly, at the top of the Receiver Dialog there is disabled. You can also introduce random noise and create a rough terrain. You can do this by setting a nonzero value for check box labeled "'''NoiseAdjust Rx Sets to Terrain Elevation''', which represent the RMS peak-to-valley amplitude of the surface roughness". The figures below show two custom terrain surfaces modeled These boxes are unchecked by the equation z = (xdefault.y)/20 defined over the range [0, 10] in both X and Y directions. Random noise has been added to both surfacesAs a result, your transmitter sets or receiver sets coincide with their associated base points in the noise amplitude being 0project workspace.2 If you check these boxes and 0.5 for the left and right figuresplace a transmitter set or a receiver set above an irregular terrain, respectivelythe transmitters or receivers are elevated from the location of their associated base points by the amount of terrain elevation as can be seen in the figure below.
[[File:PROP21To better understand why there are two separate sets of points in the scene, note that a point array (CAD object) is used to create a uniformly spaced base set.png|400px]] [[File:PROP20The array object always preserves its grid topology as you move it around the scene. However, the transmitters or receivers associated with this point array object are elevated above the irregular terrain and no longer follow a strictly uniform grid. If you move the base set from its original position to a new location, the base points' topology will stay intact, while the associated transmitters or receivers will be redistributed above the terrain based on their new elevations.png|400px]]
Figure<table><tr><td> [[Image: Two noisy custom terrain surfaces both defined as z = (xPROP MAN8.ypng|thumb|left|640px|A transmitter (red)/20: and a grid of receivers (Leftyellow) RMS noise amplitude = 0adjusted above a plateau terrain surface.2, The underlying base point sets (rightblue and orange dots) RMS noise amplitude = 0.5associated with the adjusted transmitters and receivers on the terrain are also visible in the figure.]] </td></tr></table>
=== Generating Grid-Based Terrain =Discretizing the Propagation Scene in EM.Terrano ==
Every time you create a new terrain object using Terrain Generator, an ASCII data file named "GeneratedTerrain" with a "'''.TRN'''" file extension is created and placed in your project folder. This is EM.Cube's simple native terrain file format that basically lists all === Why Do You Need to Discretize the (x, y, z) coordinates of the generated surface points on a horizontal, rectangular XY grid. Terrain Generator simply takes your custom function definition or one of the selected catalog surface types and generates the digital elevation data on the specified grid. Scene? ===
Another type of terrain model that the terrain generator provides is EM.Terrano'''XY Grid Data'''. In this case, you define s SBR solver uses a rectangular XY grid method known as Geometrical Optics (GO) in conjunction with a uniform grid cell size along the X and Y directions and manually define Uniform Theory of Diffraction (UTD) to trace the Z-elevation for each grid rays from their originating point. This is similar at the source to the surface generator's "2D Uniform Grid" model type in CubeCADindividual receiver locations. Based Rays may hit obstructing objects on your input to '''Range Start'''their way and get reflected, diffracted or transmitted. EM.Terrano'''Range Stop''' s SBR solver can only handle diffraction off linear edges and '''Range Step''' along X reflection from and Ytransmission through planar interfaces. When an incident ray hits the surface of the obstructing object, a 2D grid local planar surface assumption is set up made at the specular point. The assumptions of linear edges and displayed planar facets obviously work in a table at the bottom case of the terrain generator dialog. By default, all the Z-elevations are set to zero initially. You can click on each table cell a scene with cubic buildings and overwrite it with a new value. At the end, click the '''Create''' button of the dialog to add the new grid-based terrain object to the Navigation Treeflat global ground.
[[File:terrain10_tnIn many practical scenarios, however, your buildings may have curved surfaces, or the terrain may be irregular.png]]EM.Terrano allows you to draw any type of surface or solid geometric objects such as cylinders, cones, etc. under impenetrable and penetrable surface groups or penetrable volumes. EM.Terrano's mesh generator creates a triangular surface mesh of all the objects in your propagation scene, which is called a facet mesh. Even the walls of cubic buildings are meshed using triangular cells. This enables EM.Terrano to properly discretize composite buildings made of conjoined cubic objects.
Unlike [[EM.Cube]]'s other computational modules, the density or resolution of EM.Terrano's surface mesh does not depend on the operating frequency and is not expressed in terms of the wavelength. The sole purpose of EM.Terrano's facet mesh is to discretize curved and irregular scatterers into flat facets and linear edges. Therefore, geometrical fidelity is the only criterion for the quality of a facet mesh. It is important to note that discretizing smooth objects using a triangular surface mesh typically creates a large number of small edges among the facets that are simply mesh artifacts and should not be considered as diffracting edges. For example, each rectangular face of a cubic building is subdivided into four triangles along the two diagonals. The four internal edges lying inside the face are obviously not diffracting edges. A grid-based terrain objectlot of subtleties like these must be taken into account by the SBR solver to run accurate and computationally efficient simulations.
=== Importing & Exporting Terrain Models Generating the Facet Mesh ===
You can import two types view and examine the discretized version of terrain in EM.Cubeyour scene's [[Propagation Module]]objects as they are sent to the SBR simulation engine. The first type is "'''.TRN"''' terrain file, which is EM.Cube's native terrain format. It is a basic digital elevation map with a very simple ASCII data file format. The You can adjust the mesh resolution and increase the geometric fidelity of discretization by creating more and finer triangular facets. On the terrain map in other hand, you may want to reduce the X mesh complexity and Y directions is specified in meters as STEPS. The (x, y, z) coordinates of send to the terrain points are then listed one point per lineSBR engine only a few coarse facets to model your buildings. The other type resolution of terrain format supported by EM.Cube Terrano's facet mesh generator is controlled by the standard '''7.5min DEMCell Edge Length''' file format with parameter, which is expressed in project length units. The default mesh cell size of 100 units might be too large for non-flat objects. You may have to set a '''smaller cell edge length in EM.DEMTerrano''' file extensions Mesh Settings dialog, along with a lower curvature angle tolerance value to capture the curvature of your curved structures adequately.
To import an external terrain model, first you have to create a terrain group node in the Navigation Tree. Right click on the name of the terrain group in the Navigation Tree and select either '''Import Terrain.<table><tr><td> [[Image:prop_manual-29.png|thumb|left|480px|EM.Terrano''' or '''Import DEM File...''' A standard Windows '''Open Dialog''' opens up, with the file type set to .TRN or .DEM extensions, respectively. You can browse your folders and find the right terrain model file to imports mesh settings dialog.]] </td></tr></table>
You can also export all the terrain objects in the project workspace as a terrain file with a '''.TRN''' file extension. You can even import a DEM terrain model from an external file and then save and export it as a native terrain (.TRN) file. To export the terrain, select '''File''' > '''Export...''' from [[Propagation ModuleImage:Info_icon.png|30px]]'s '''File Menu'''. The standard Windows Save Dialog opens up with the default file type set Click here to learn more about '''[[Preparing_Physical_Structures_for_Electromagnetic_Simulation#Working_with_EM.TRN'''Cube. Type in a name for your new terrain file and click the 27s_Mesh_Generators | Working with Mesh Generator]]'''Save''' button to export the terrain data.
[[FileImage:prop_manual-12_tnInfo_icon.png|30px]]Click here to learn more about the properties of '''[[Glossary_of_EM.Cube%27s_Simulation-Related_Operations#Facet_Mesh | EM.Terrano's Facet Mesh Generator]]'''.
Figure 1<table><tr><td> [[Image: An imported external terrain modelUrbanCanyon2.png|thumb|left|640px|The facet mesh of the buildings in the urban propagation scene generated by EM.Terrano's Random City wizard with a cell edge length of 100m.]] </td></tr><tr><td> [[Image:UrbanCanyon3.png|thumb|left|640px|The facet mesh of the buildings in the urban propagation scene generated by EM.Terrano's Random City wizard with a cell edge length of 10m.]] </td></tr></table>
=== Multilayer Surface Models =Running Ray Tracing Simulations in EM.Terrano ==
Most of the time, your outdoor propagation scene consists of simple buildings made of single-layer walls with standard material properties (e<sub>r</sub> and s)EM. In the case of Terrano provides a single-layer impenetrable surface, the specular interface is an infinite dielectric half-space, which reflects the impinging rays. Single-layer penetrable surfaces, on the other hand, involve finite-thickness dielectric walls, which both reflect and transmit the incident rays. Similarly, most number of your indoor propagation scenes involve simple single-layer penetrable walls with the specified material properties e<sub>r</sub> and s. A thin wall acts like a finite-thickness dielectric slab that both reflects and transmits incident rays. In the case of the global ground different simulation or terrain objects, only ray reflection off the ground surface is considered.solver types:
In EM.Cube's [[Propagation Module]], you can define multilayer surfaces with both reflection and transmission properties. You can define multilayer impenetrable buildings, multilayer penetrable walls, and multilayer terrain, with an arbitrary number of layers having different material compositions. You define a multilayer surface in the property dialog of a block, whether impenetrable, penetrable or terrain. In the section entitled '''Surface Type''', two options are available: '''Standard Material''' or '''User Defined Model'''. For simple multilayer walls, select the '''Standard Material''' option. You can add new layers with arbitrary thickness and material parameters to the existing layers. To insert a new layer, deselect any items in the layer list, and click the '''Add/Edit''' button to open the "Add Layer" Dialog. Here you can enter a name for the new layer and values for its '''Thickness''', e<sub>r</sub> and s. You may also delete any layer by selecting and highlighting it and clicking the '''Delete''' button. You can move layers up or down using the '''Move Up''' and '''Move Down''' buttons and change the layer hierarchy.* 3D Field Solver* SBR Channel Analyzer* Log-Haul Channel Analyzer* Communication Link Solver* Radar Link Solver
You can also search The first three simulation types are described below. For a description of EM.CubeTerrano's material database by clicking the '''Material''' button of "Add Layer" or "Edit Layer" dialogs. This opens the '''Materials''' Dialog. Inside the material list select and highlight any row and click the '''OK''' button. The selected material will fill out all the fields in the "Add Layer" or "Edit Layer" dialogs. Inside the Materials DialogRadar Simulator, you can type the few first letters of any material, and it will take you to the corresponding row of the listfollow this link.
[[File:PROP26.png]]=== Running a Single-Frequency SBR Analysis ===
Figure 1:Propagation ModuleIts main solver is the '''3D SBR Ray Tracer'''. Once you have set up your propagation scene in EM.Terrano and have defined sources/transmitters and observables/receivers for your scene, you are ready to run a SBR ray tracing simulation. You set the simulation mode in EM.Terrano's Penetrable Surface Dialog showing simulation run dialog. A single-frequency SBR analysis is a threesingle-layer wall compositionrun simulation and the simplest type of ray tracing simulation in EM.Terrano. It involves the following steps:
[[File:PROP24* Set the units of your project and the frequency of operation. Note that the default project unit is '''millimeter'''. Wireless propagation problems usually require meter, mile or kilometer as the project unit.* Create the blocks and draw the buildings at the desired locations.* Keep the default ray domain and accept the default global ground or change its material properties.* Define an excitation source and observables for your project.* If you intend to use transmitters and receivers in your scene, first define the required base sets and then define the transmitter and receiver sets based on them.* Run the SBR simulation engine.* Visualize the coverage map and plot other data.png]]
Figure 2: You can access EM.CubeTerrano's material listSimulation Run dialog by clicking the '''Run''' [[File:run_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Simulate → Run...''' or using the keyboard shortcut {{key|Ctrl+R}}. When you click the {{key|Run}} button, a new window opens up that reports the different stages of the SBR simulation and indicates the progress of each stage. After the SBR simulation is successfully completed, a message pops up and prompts the completion of the process.
=== Transferring Objects From Or To Other Modules ===<table><tr><td> [[Image:Terrano L1 Fig16.png|thumb|left|480px|EM.Terrano's simulation run dialog.]] </td></tr></table>
When you start a new project in <table><tr><td> [[Image:PROP MAN10.png|thumb|left|550px|EM.CubeTerrano's [[Propagation Moduleoutput message window.]] and draw a solid object like a box in the project workspace without having defined any surface groups, it is assumed to be of the impenetrable surface type. A default impenetrable surface group called Block_1 is automatically added to the Navigation Tree, which holds your newly drawn object. The default group has the material properties of "Brick" (e<sub/td>r</subtr> = 4.4 and s = 0.001 S</m.) with a dark brown color. You can continue drawing new objects in the project workspace and adding them under this block node. Or you can define a new surface type with different properties. By default, the last surface group that was defined is '''Active'''. The current active surface group is always listed in bold letters in the Navigation Tree. When you draw a new object, it is always inserted under the current active surface group. Any surface group can be activated by right clicking its name in the Navigation Tree and selecting the '''Activate''' item of the contextual menu.table>
You can move any object from its current surface group into any other available surface group. First select === Changing the object, then right click on its surface and select '''MoveTo > Propagation >'''. A submenu appears which lists all the available surface groups where you can transfer the selected object. You can also move objects among surface groups by selecting their names in the Navigation Tree and using the contextual menu. In a similar way, you can transfer objects from [[Propagation Module]] to EM.Cube's other modules or vice versa. '''Keep in mind that all the external model files such as STEP, IGES, STL, etc. are first imported to EM.Cube's CubeCAD, from which you can transfer them to other modules.''' First select the object, then right click and select '''MoveTo >'''. In the submenu you will see a list of all the EM.Cube modules that have at least one available group where you can transfer your selected object. You can select multiple objects for transfer. When using the keyboard's '''Shift Key''' or '''Ctrl Key''' for multiple selection, make sure that those keys are held down, when you right click to access the contextual menu.SBR Engine Settings ===
== Defining Sources & Observables ==There are a number of SBR simulation settings that can be accessed and changed from the Ray Tracing Engine Settings Dialog. To open this dialog, click the button labeled {{key|Settings}} on the right side of the '''Select Simulation or Solver Type''' drop-down list in the Run Dialog. EM.Terrano's SBR simulation engine allows you to separate the physical effects that are calculated during a ray tracing process. You can selectively enable or disable '''Reflection/Transmission''' and '''Edge Diffraction''' in the "Ray-Block Interactions" section of this dialog. By default, ray reflection and transmission and edge diffraction effects are enabled. Separating these effects sometimes help you better analyze your propagation scene and understand the impact of various blocks in the scene.
Like every other electromagnetic solver, EM.Cube's SBR ray tracer requires Terrano allows a source finite number of ray bounces for excitation each original ray emanating from a transmitter. This is very important in situations that may involve resonance effects where rays get trapped among multiple surfaces and one or more observables for generation of simulation datamay bounce back and forth indefinitely. EMThis is set using the box labeled "'''Max No.CubeRay Bounces's new [[Propagation Module]] offers several types of sources and observables for ''", which has a SBR default value of 10. Note that the maximum number of ray bounces directly affects the computation time as well as the size of output simulationdata files. You This can mix become critical for indoor propagation scenes, where most of the rays undergo a large number of reflections. Two other parameters control the diffraction computations: '''Max Wedge Angle''' in degrees and match different source types and observable types depending on '''Min Edge Length''' in project units. The maximum wedge angle is the requirements angle between two conjoined facets that is considered to make them almost flat or coplanar with no diffraction effect. The default value of your modeling problemthe maximum wedge angle is 170°. There are The minimum edge length is size of the common edge between two types conjoined facets that is considered as a mesh artifact and not a real diffracting edge. The default value of sources:the minimum edge length is one project units.
* [[#Defining Transmitter Sets|Transmitter]]<table><tr><td> * [[#Hertzian Dipole SourcesImage:PROP MAN11.png|Hertzian Dipolethumb|left|720px|EM.Terrano's SBR simulation engine settings dialog.]]</td></tr></table>
There As rays travel in the scene and bounce from surfaces, they lose their power, and their amplitudes gradually diminish. From a practical point of view, only rays that have power levels above the receiver sensitivity can be effectively received. Therefore, all the rays whose power levels fall below a specified power threshold are four types discarded. The '''Ray Power Threshold''' is specified in dBm and has a default value of -150dBm. Keep in mind that the value of this threshold directly affects the accuracy of the simulation results as well as the size of observables:the output data file.
* [[#Defining Receiver Sets|Receivers]]* [[#Defining Field Sensors|Field Sensor]]* Far Fields* Huygens SurfaceYou can also set the '''Ray Angular Resolution''' of the transmitter rays in degrees. By default, every transmitter emanates equi-angular ray tubes at a resolution of 1 degree. Lower angular resolutions larger than 1° speed up the SBR simulation significantly, but they may compromise the accuracy. Higher angular resolutions less than 1° increase the accuracy of the simulating results, but they also increase the computation time. The SBR Engine Settings dialog also displays the '''Recommended Ray Angular Resolution''' in degrees in a grayed-out box. This number is calculated based on the overall extents of your computational domain as well as the SBR mesh resolution. To see this value, you have to generate the SBR mesh first. Keeping the angular resolution of your project above this threshold value makes sure that the small mesh facets at very large distances from the source would not miss any impinging ray tubes during the simulation.
The simplest SBR simulation can be performed using a short dipole source with a specified field sensor plane. In this way, EM.Cube computes Terrano gives a few more options for the electric and magnetic fields radiated by your dipole source in the presence ray tracing solution of your multipath propagation environmentproblem. A "classic" urban propagation scene can be set up using a "Transmitter" source and an array For instance, it allows you to exclude the direct line-of "Receiver" observables-sight (LOS) rays from the final solution. A transmitter There is a point radiator with a user defined radiation pattern. A receiver check box for this purpose labeled "Exclude direct (LOS) rays from the solution", which is a polarization-matched isotropic point radiator that collects unchecked by default. EM.Terrano also allows you to superpose the received rays at its apertureincoherently. Using receiversIn that case, you can calculate the powers of individual ray are simply added to compute that total received power coverage map of your propagation scene. You can also calculate your channel's path loss between This option in the transmitter and all the receiverscheck box labeled "Superpose rays incoherently" is disabled by default, too. <br />
=== Hertzian Dipole Sources ===At the end of a ray tracing simulation, the electric field of each individual ray is computed and reported. By default, the actual received ray fields are reported, which are independent of the radiation pattern of the receive antennas. EM.Terrano provides a check box labeled "Normalize ray's E-field based on receiver pattern", which is unchecked by default. If this box is checked, the field of each ray is normalized so as to reflect that effect of the receiver antenna's radiation pattern. The received power of each ray is calculated from the following equation:
Earlier versions of EM.Cube's [[Propagation Module]] used to offer an isotropic radiator with vertical or horizontal polarization as the simplest transmitter type. This release of EM.Cube has abandoned isotropic radiator transmitters because they do not exist physically in a real world. Instead, the default transmitter radiator type is now a Hertzian dipole. Note that before defining a transmitter, first you have to define a base set to establish the location of the transmitter. Most simulation scenes involve only a single transmitter. Your base set can be made up of a single point for this purpose. <math> P_{ray} = \frac{ | \mathbf{E_{norm}} |^2 }{2\eta_0} \frac{\lambda_0^2}{4\pi} </math>
To define a new Transmitter Set, go to It can be seen that if the ray'''Sources''' section of the Navigation Trees E-field is not normalized, right click on the '''Transmitters''' item and select '''Insert Transmitter...''' A dialog opens up that contains a default name for the new Transmitter Set as well as a dropdown list labeled '''Select Base Set'''. In this list you computed ray power will see all the available base sets already defined in the project workspace. Select the desired base set correspond to associate with the transmitter set. Note that if the base set contains more than one point, then more than one transmitter will be created and contained in your transmitter set. After defining of a transmitter set, the base points change their color to the transmitter color, which is red by defaultpolarization matched isotropic receiver.
In the "Radiator" section of the dialog, you have two options to choose from: "Short Dipole" and "User Defined". The default option is short dipole. A short dipole radiator has a '''Length'''''dl'' expressed in project units, a current '''Amplitude''' in Amperes and a current '''Phase''' in degrees. The '''Direction''' of the dipole is determined by its unit vector that has three X, Y and Z components. By default, a Z-directed short dipole radiator is assumed. You can change all parameters of the dipole as you wish. Keep in mind that all the transmitters belonging to the same set have parallel radiators with identical properties. === Polarimetric Channel Analysis ===
[[File:PROP18(1)In a 3D SBR simulation, a transmitter shoots a large number of rays in all directions. The electric fields of these rays are polarimetric and their strength and polarization are determined by the designated radiation pattern of the transmit antenna. The rays travel in the propagation scene and bounce from the ground and buildings or other scatterers or get diffracted at the building edges until they reach the location of the receivers. Each individual ray has its own vectorial electric field and power. The electric fields of the received rays are then superposed coherently and polarimetrically to compute the total field at the receiver locations. The designated radiation pattern of the receivers is then used to compute the total received power by each individual receiver.png]]
Figure 1: [[Propagation Module]]From a theoretical point of view, the radiation patterns of the transmit and receive antennas are independent of the propagation channel characteristics. For the given locations of the point transmitters and receivers, one can assume ideal isotropic radiators at these points and compute the polarimetric transfer function matrix of the propagation channel. This matrix relates the received electric field at each receiver location to the transmitted electric field at each transmitter location. In general, the vectorial electric field of each individual ray is expressed in the local standard spherical coordinate system at the transmitter and receiver locations. In other words, the polarimetric channel matrix expresses the 's Transmitter dialog ''E<sub>θ</sub>''' and '''E<sub>φ</sub>''' field components associated with each ray at the receiver location to its '''E<sub>θ</sub>''' and '''E<sub>φ</sub>''' field components at the transmitter location. Each ray has a short dipole radiator selecteddelay and θ and φ angles of departure at the transmitter location and θ and φ angles of departure at the receiver location.
=== Defining Base Point Sets ===To perform a polarimatric channel characterization of your propagation scene, open EM.Terrano's Run Simulation dialog and select '''Channel Analyzer''' from the drop-down list labeled '''Select Simulation or Solver Type'''. At the end of the simulation, a large ray database is generated with two data files called "sbr_channel_matrix.DAT" and "sbr_ray_path.DAT". The former file contains the delay, angles of arrival and departure and complex-valued elements of the channel matrix for all the individual rays that leave each transmitter and arrive at each receiver. The latter file contains the geometric aspects of each ray such as hit point coordinates.
In order to tie up transmitters and receivers with CAD objects in the project workspace, EM.Cube uses point objects to define transmitters and receivers. These point objects represent the base of the location of transmitters and receivers in the computational domain. Hence, they are grouped together as "Base Sets". You can easily interchange the role of transmitters and receivers in a scene by switching their associated bases. === The usefulness of concept of base sets will become apparent later when you place transmitters or receivers on an irregular terrain and adjust their elevation. "Near Real-Time" Polarimatrix Solver ===
To create After EM.Terrano's channel analyzer generates a new base setray database that characterizes your propagation channel polarimetrically for all the combinations of transmitter and receiver locations, right click on a ray tracing solution of the propagation problem can readily be found in almost real time by incorporating the effects of the radiation patterns of transmit and receive antennas. This is done using the '''Base SetsPolarimatrix Solver''' item , which is the third option of Navigation Tree and select the drop-down list labeled '''Insert Base Set...Select Simulation or Solver Type''' A in EM.Terrano's Run Simulation dialog for setting up . The results of the Polarimatrix and 3D SBR solvers must be identical from a theoretical point of view. However, there might be small discrepancies between the Base Set properties opens uptwo solutions due to roundoff errors.
# Enter a name for Using the base set and change the default blue color if you wish. It is useful Polarimatrix solver can lead to differentiate a significant reduction of the base sets associated with total simulation time in sweep simulations that involve a large number of transmitters and receivers by their color.# Click Certain simulation modes of EM.Terrano are intended for the '''OK''' button to close Polarimatrix solver only as will be described in the Base Set Dialognext section.
[[File:PROP1{{Note| In order to use the Polarimatrix solver, you must first generate a ray database of your propagation scene using EM.png]]Terrano's Channel Analyzer.}}
Figure 1: [[Propagation Module]]=== EM.Terrano's Base Set dialog.Simulation Modes ===
Once a base set node has been added to the Navigation Tree, it becomes the active node for new object drawingEM. Under base sets, you can only draw point objects. All other object creation tools are disabled. A point is initially drawn on the XY plane. Make sure to change the Z-coordinate of your radiator, otherwise, it will fall on the global ground at z = 0. You can also create arrays of base points under the same base set. This is particularly useful for setting up receiver grids to compute coverage maps. Simply select Terrano provides a point object and click the '''Array Tool''' number of '''Tools Toolbar''' different simulation modes that involve single or use the keyboard shortcut "A". Enter values for the X, Y or Z spacing as well as the number of elements along these three directions in the Array Dialog. In most propagation scenes you are interested in 2D horizontal arrays along a fixed Z coordinate (parallel to the XY plane).multiple simulation runs:
{| class="wikitable"|-! scope="col"| Simulation Mode! scope= Defining "col"| Usage! scope="col"| Which Solver?! scope="col"| Frequency ! scope="col"| Restrictions|-| style="width:120px;" | [[#Running a Single-Frequency SBR Analysis | Single-Frequency Analysis]]| style="width:180px;" | Simulates the propagation scene "As Is"| style="width:150px;" | SBR, Channel Analyzer, Polarimatrix, Radar Simulator| style="width:120px;" | Runs at the center frequency fc| style="width:300px;" | None|-| style="width:120px;" | [[Parametric_Modeling_%26_Simulation_Modes_in_EM.Cube#Running_Frequency_Sweep_Simulations_in_EM.Cube | Frequency Sweep]]| style="width:180px;" | Varies the operating frequency of the ray tracer | style="width:150px;" | SBR, Channel Analyzer, Polarimatrix, Radar Simulator| style="width:120px;" | Runs at a specified set of frequency samples| style="width:300px;" | None|-| style="width:120px;" | [[Parametric_Modeling_%26_Simulation_Modes_in_EM.Cube#Running_Parametric_Sweep_Simulations_in_EM.Cube | Parametric Sweep]]| style="width:180px;" | Varies the value(s) of one or more project variables| style="width:150px;" | SBR| style="width:120px;" | Runs at the center frequency fc| style="width:300px;" | Requires definition of sweep variables, works only with SBR solver as the physical scene may change during the sweep |-| style="width:120px;" | [[#Transmitter_Sweep | Transmitter Sets Sweep]]| style="width:180px;" | Activates two or more transmitters sequentially with only one transmitter broadcasting at each simulation run | style="width:150px;" | Polarimatrix| style="width:120px;" | Runs at the center frequency fc| style="width:300px;" | Requires at least two transmitters in the scene, works only with Polarimatrix solver and requires an existing ray database|-| style="width:120px;" | [[#Rotational_Sweep | Rotational Sweep]]| style="width:180px;" | Rotates the radiation pattern of the transmit antenna(s) sequentially to model beam steering | style="width:150px;" | Polarimatrix| style="width:120px;" | Runs at the center frequency fc| style="width:300px;" | Works only with Polarimatrix solver and requires an existing ray database|-| style="width:120px;" | [[#Mobile_Sweep | Mobile Sweep]]| style="width:180px;" | Considers one pair of active transmitter and receiver at each simulation run to model a mobile communication link| style="width:150px;" | Polarimatrix| style="width:120px;" | Runs at the center frequency fc| style="width:300px;" | Requires the same number of transmitters and receivers, works only with Polarimatrix solver and requires an existing ray database|}
A short dipole is Click on each item in the closest thing above list to an omni-directional radiator. The direction or orientation of the short dipole determines its polarization. In many applications, you may rather want to use a directional antenna for your transmitter. You can model a radiating structure using EM.Cube's FDTD, Planar, MoM3D or PO modules and generate a 3D radiation pattern data file for it. These data are stored in a specially formatted file with a "'''.RAD'''" extension, which contains columns of spherical φ and θ angles as well as the real and imaginary parts of the complex-valued far field components '''E<sub>θ</sub>''' and '''E<sub>φ</sub>'''. The θ- and φ-components of the far-zone electric field determine the polarization of the transmitting radiatorlearn more about each simulation mode.
To define a directional transmitter radiator, you need to select You set the "User Defined" option simulation mode in the "Radiator" section of the Transmitter DialogEM. You can do this either at the time of creating a transmitter set, or afterwards by opening the property Terrano's simulation run dialog of the transmitter set. In the "Custom Pattern Parameters", click using the drop-down list labeled '''Import PatternSimulation Mode''' button to set the path for the radiation data file. This opens up the standard Windows Open dialog, with the default file type or extension set to ".RAD". Browse your folders to find the right data file. A radiation pattern file usually contains the value of "Total Radiated Power" in its file header. This single-frequency analysis is used by default for power calculations in the SBR a single-run simulation. However, you can check All the box labeled "'''Custom Power'''" and enter a value for the transmitter power other simulation modes in Watts. EM.Cube can also rotate the imported radiation pattern arbitrarilyabove list are considered multi-run simulations. In this case, you need to specify the '''Rotation''' angles in degrees about the Xmulti-run simulation modes, Y- and Z-axes. Note that these rotations certain parameters are performed sequentially varied and in order: first a rotation about collection of simulation data files are generated. At the X-axis, then end of a rotation about the Y-axissweep simulation, and finally a rotation about you can plot the Z-axisoutput parameter results on 2D graphs or you can animate the 3D simulation data from the navigation tree.
[[File:PROP19(1){{Note| EM.png]] [[File:PROP20Terrano's frequency sweep simulations are very fast because the geometrical optics (1ray tracing)part of the simulation is frequency-independent.png]]}}
Figure 1: [[Propagation Module]]'s === Transmitter dialog with a user defined radiator selected.Sweep ===
=== Multiple Transmitters vsWhen your propagation scene contains two or more transmitters, whether they all belong to the same transmitter set with the same radiation pattern or to different transmitter sets, EM.Terrano assumes all to be coherent with respect to one another. In other words, synchronous transmitters are always assumed. The rays originating from all these transmitters are superposed coherently and vectorially at each receiver. In a transmitter sweep, on the other hand, EM.Terrano assumes only one transmitter broadcasting at a time. The result of the sweep simulation is a number of received power coverage maps, each corresponding to a transmitter in the scene. Antenna Arrays ===
{{Note| EM.CubeTerrano's SBR simulations are fully coherent and 3D-polarimetric. This means that the phase and polarization of all the rays are maintained and processed during their bounces in the scene. Your propagation scene can have more than one transmitter. During an SBR simulation, all the rays emanating from all the transmitters are traced in the propagation scene. All the received rays at a given receiver location are summed coherently and vectorially. This is based on the principle of linear superposition. All the transmitters belonging to the same transmitter set have the same radiation properties. They are either parallel short dipole radiators sweep works only with the same current amplitudes Polarimatrix Solver and phases, or parallel user defined radiators with identical radiation patterns. As these transmitters are placed at different spatial locations, they effectively form requires an antenna array with identical elements. The array factor is simply determined by existing ray database previously generated using the coordinates of the base points. If you want to have different amplitude or phases, then you need to define different transmitter setsChannel Analyzer.}}
If that radiators are indeed the elements of an actual antenna array with a half wavelength spacing or so, we recommend that you import the radiation pattern of the array structure instead and replace the whole multi-radiator system with a single point transmitting radiator in your propagation scene. This case is usually encountered in MIMO systems, and using an equivalent point transmitter is an acceptable approximation because the total size of the array aperture is usually much smaller than the dimensions of your propagation scene and its representative length scales. In that case, you need to position the equivalent point radiator at the radiation center of the antenna array. This depends on the physical structure of the antenna array. However, keep in mind that any reasonable guess may still provide a good approximation without any significant error in the received ray data. === Rotational Sweep ===
=== Defining Receiver Sets ===You can rotate the 3D radiation patterns of both the transmitters and receivers from the property dialog of the parent transmitter set or receiver set. This is done in advance before a SBR simulation starts. You can define one or more of the rotation angles of a transmitter set or a receiver set as sweep variables and perform a parametric sweep simulation. In that case, the entire scene and all of its buildings are discretized at each simulation run and a complete physical SBR ray tracing simulation is carried out. However, we know that the polarimetric characteristics of the propagation channel are independent of the transmitter or receiver antenna patterns or their rotation angles. A rotational sweep allows you to rotate the radiation pattern of the transmitter(s) about one of the three principal axes sequentially. This is equivalent to the steering of the beam of the transmit antenna either mechanically or electronically. The result of the sweep simulation is a number of received power coverage maps, each corresponding to one of the angular samples. To run a rotational sweep, you must specify the rotation angle.
Receivers act as observables in a propagation scene{{Note| EM. The objective of a SBR simulation is to calculate Terrano's rotational sweep works only with the far-zone electric fields Polarimatrix Solver and requires an existing ray database previously generated using the total received power at the location of a receiver. In that sense, receivers indeed act as field observation points. You need to define at least one receiver in the scene before you can run a SBR simulation. You define the receivers of your scene by associating them with the base sets you have already defined in the project workspace. Unlike transmitters that usually one or few, a typical propagation scene may involve a large number of receivers. To generate a wireless coverage map, you need to define an array of points as your base setChannel Analyzer. }}
To define a new Receiver Set, go to the Observables section of the Navigation Tree, right click on the '''Receivers''' item and select '''Insert Receiver...''' A dialog opens up that contains a default name for the new Receiver Set as well as a dropdown list labeled '''Select Radiator Set'''. In this list you will see all the available base sets that you have already define in the project workspace. Select and designate the desired base set as the receiver set. Note that if the base set contains more than one point, all of them are designated as receivers. After defining a receiver set, the points change their color to the receiver color, which is yellow by default. The first element of the set is represented by a larger ball of the same color indicating that it is the selected receiver in the scene. The Receiver Set Dialog is also used to access individual receivers of the set for data visualization at the end of a simulation. At the end of an SBR simulation, the button labeled "Show Ray Data" becomes enabled. Clicking this button opens the Ray Data Dialog, where you can see a list of all the received rays at the selected receiver and their computed characteristics. === Mobile Sweep ===
[[File:PROP21In a mobile sweep, each transmitter is paired with a receiver according to their indices in their parent sets. At each simulation run, only one (1Tx, Rx)pair is considered to be active in the scene. As a result, the generated coverage map takes a different meaning implying the sequential movement of the transmitter and receiver pair along their corresponding paths. In other words, the set of point transmitters and the set of point receivers indeed represent the locations of a single transmitter and a single receiver at different instants of time. It is obvious that the total number of transmitters and total number of receivers in the scene must be equal. Otherwise, EM.png]] [[File:PROP22Terrano will prompt an error message.png]]
Figure 1: [[Propagation ModuleEM.Cube]]provides a 's Receiver dialog''Mobile Path Wizard''' that facilitates the creation of a transmitter set or a receiver set along a specified path. This path can be an existing nodal curve (polyline or NURBS curve) or an existing line objects. You can also import a sptial Cartesian data file containing the coordinates of the base location points. For more information, refer to [[Glossary_of_EM.Cube%27s_Wizards#Mobile_Path_Wizard | Mobile Path Wizard]].
=== Defining Field Sensors ==={{Note| EM.Terrano's mobile sweep works only with the Polarimatrix Solver and requires an existing ray database previously generated using the Channel Analyzer.}}
[[File:PMOM90.png|thumb|[[=== Investigating Propagation Module]]'s Field Sensor dialog]]As an asymptotic electromagnetic field solver, the SBR simulation engine can compute the electric and magnetic field distributions in Effects Selectively One at a specified plane. In order to view these field distributions, you must first define field sensor observables before running the SBR simulation. To do that, right click on the '''Field Sensors''' item in the '''Observables''' section of the Navigation Tree and select '''Insert New Observable...'''. The Field Sensor Dialog opens up. At the top of the dialog and in the section titled '''Sensor Plane Location''', first you need to set the plane of field calculation. In the dropdown box labeled '''Direction''', you have three options X, Y, and Z, representing the"normals" to the XY, YZ and ZX planes, respectively. The default direction is Z, i.e. XY plane parallel to the substrate layers. In the three boxes labeled '''Coordinates''', you set the coordinates of the center of the plane. Then, you specify the '''Size''' of the plane in project units, and finally set the '''Number of Samples''' along the two sides of the sensor plane. The larger the number of samples, the smoother the near field map will appear. Time ===
In the section titled Output Settingsa typical SBR ray tracing simulation, you can also select the field map type from two options: '''Confetti''' and '''Cone'''EM. The former produces an intensity plot for field amplitude and phase, while Terrano includes all the latter generates a 3D vector plot. In the confetti casepropagation effects such as direct (LOS) rays, you have an option to check the box labeled '''Data Interpolation'''ray reflection and transmission, which creates a smooth and blended (digitally filtered) mapedge diffractions. In At the cone caseend of a SBR simulation, you can set visualize the size received power coverage map of your propagation scene, which appears under the vector cones that represent receiver set item in the field directionnavigation tree. At The figure below shows the end received power coverage map of the random city scene with a sweep simulation, multiple field map are produced vertically polarized half-wave dipole transmitter located 10m above the ground and added to a large grid of vertically polarized half-wave dipole receivers placed 1.5m above the Navigation Treeground. You can animate these maps. However, during The legend box shows the sweep only one field type is stored, either limits of the Ecolor map between -field or H23dBm as the maximum and -field. You can choose 150dB (the field type for multiple plots using the radio buttons in the section titled '''Field Display - Multiple Plots'''. The default choice is receiver sensitivity value) as the E-fieldminimum.
Once you close the Field Sensor dialog, its name is added under the '''Field Sensors''' node <table><tr><td> [[Image:UrbanCanyon10.png|thumb|left|640px|The received power coverage map of the Navigation Treerandom city scene with a dipole transmitter. At the end of a SBR simulation, the field sensor nodes in the Navigation Tree become populated by the magnitude and phase plots of the three vectorial components of the electric ('''E''') and magnetic ('''H''') field as well as the total electric and magnetic fields defined in the following manner:]] </td></tr></table>
[[File:PMOM88Sometime it is helpful to change the scale of the color map to better understand the dynamic range of the coverage map. If you double-click on the legend or right-click on the coverage map's name in the navigation tree and select '''Properties''', the Plot Settings dialog opens up. Select the '''User-Defined''' item and set the lower and upper bounds of color map as you wish.png]]
=== Computing Radiation Patterns In SBR ===<table><tr><td> [[Image:UrbanCanyon15.png|thumb|left|480px|The plot settings dialog of the coverage map.]] </td></tr></table><table><tr><td> [[Image:UrbanCanyon16.png|thumb|left|640px|The received power coverage map of the random city scene with a user-defined color map scale between -80dBm and -20dBm.]] </td></tr></table>
Coming SoonTo better understand the various propagation effects, EM.Terrano allows you to enable or disable these effects selectively.This is done from the Ray Tracing Simulation Engine Settings dialog using the provided check boxes.
== Scene Discretization & Adjustment ==<table><tr><td> [[Image:UrbanCanyon14.png|thumb|left|640px|EM.Terrano's simulation run dialog showing the check boxes for controlling various propagation effects.]] </td></tr></table>
=== <table><tr><td> [[Image:UrbanCanyon11.png|thumb|left|640px|The Need For Discretization Of Propagation Scene ===received power coverage map of the random city scene with direct LOS rays only.]] </td></tr><tr><td> [[Image:UrbanCanyon12.png|thumb|left|640px|The received power coverage map of the random city scene with reflected rays only.]] </td></tr><tr><td> [[Image:UrbanCanyon13.png|thumb|left|640px|The received power coverage map of the random city scene with diffracted rays only.]] </td></tr></table>
In a typical SBR simulation, a ray is traced from the location of the source until it hits a scatterer. The SBR method assumes that the ray hits either a flat facet of the scatterer or one of its edges. In the case of hitting a flat facet, the specular point is used to launch new reflected and transmitted rays. The surface of the facet is treated as an infinite dielectric medium interface, at which the reflection and transmission coefficients are calculated. In the case of hitting an edge, new diffracted rays are generated in the scene. However, only those who reach a nearby receiver in their line of sight are ever taken into account. In other words, diffractions are treated locally== Working with EM.Terrano's Simulation Data ==
EM.Cube=== The Ray Tracing Solvers's [[Propagation Module]] allows you to draw any type of surface or solid CAD objects under impenetrable and penetrable surface groups. Some of these objects have flat faces such as boxes, pyramids, rectangle or triangle strips, etc. Some others contain curved surfaces or curved boundaries such as cylinders, cones, etc. All the non-flat surfaces have to be discretized in the form of a collection of smaller flat facets. EM.Cube uses a triangular surface mesh generator to discretize the penetrable and impenetrable surface objects of your propagation scene. This mesh generator is very similar to the ones used in EM.Cube's two other modules: MoM3D and Physical Optics (PO). Output Simulation Data ===
You can build Both the SBR solver and the Polarimatrix solver perform the same type of simulation but in two different ways. The SBR solver discretizes the scene including all the buildings and terrain, shoots a variety large number of surface rays from the transmitters and solid objects collects the rays at the receivers. The Polarimatrix solver does the same thing using an existing polarimetric ray database that has been previously generated using EM.CubeTerrano's native "Curve" CAD objects like linesChannel Analyzer. It incorporates the effects of the radiation patterns of the transmit and receive antennas in conjunction with the polarimetric channel characteristics. At the end of a ray tracing simulation, polylinesall the polarimetric rays emanating from the transmitter(s) or other sources that are received by the individual receivers are computed, circlescollected, etcsorted and saved into ASCII data files. You can use tools like ExtrudeFrom the ray data, Loftthe total electric field at the location of receivers as well as the total received power are computed. The individual ray data include the field components of each ray, Strip-Sweepthe ray's elevation and azimuth angles of departure and arrival (departure from the transmitter location and arrival at the receiver location), Pipe-Sweep, etc. and time delay of the received ray with respect to transform curves into surface or solid objectsthe transmitter. '''HoweverIf you specify the temperatures, keep noise figure and transmission line losses in mind that all the "Curve" CAD objects are ignored by definition of the SBR mesh generator receiver sets, the noise power level and are therefore not sent signal-to -noise ratio (SNR) at each receiver are also calculated, and so are the simulation engineE<sub>b</sub>/N<sub>0</sub> and bit error rate (BER) for the selected digital modulation scheme.'''
=== Viewing SBR Mesh Visualizing Field & Received Power Coverage Maps ===
You can view and examine the discretized version of your scene objects as they are sent to the SBR simulation engine. To view the meshIn wireless propagation modeling for communication system applications, click the '''Mesh''' [[File:mesh_tool.png]] button of received power at the Simulate Toolbar or select '''Simulate > Discretization > Show Mesh''', or use receiver location is more important than the keyboard shortcut '''Ctrl+M'''. A triangular surface mesh of your physical structure appears in the project workspacefield distributions. In this case, EM.Cube enters it mesh view mode. You can perform view operations like rotate view, pan, zoom, etc. But you cannot select objects, or move them or edit their properties. To get out of the Mesh View and return order to EM.Cube's Normal View, press compute the '''Esc Key''' of the keyboardreceived power, or click the Mesh button you need three pieces of the Simulate Toolbar once again, or go to the Simulate Menu and deselect the '''Discretization >''' '''Show Mesh''' item.information:
You can adjust * '''Total Transmitted Power (EIRP)''': This requires knowledge of the mesh resolution and increase baseband signal power, the geometric fidelity transmitter chain parameters, the transmission characteristics of discretization by creating more and finer triangular facets. On the other hand, you may want transmission line connecting the transmitter circuit to reduce the mesh complexity transmitting antenna and send to the SBR engine only a few coarse facets to model your buildingsradiation characteristics of the transmitting antenna. To adjust the mesh resolution, open the Mesh Settings Dialog by clicking the * '''Mesh SettingsChannel Path Loss''' [[File:mesh_settingsThis is computed through SBR simulation.png]] button of the Simulate Toolbar or select * '''Simulate > Discretization >Receiver Properties''' '''Mesh Settings...'''. : This dialog provides a single parameters: '''Edge Length'''., which has a default value includes the radiation characteristics of 100 project units. If you are already in the Mesh View Mode and open the Mesh Settings Dialogreceiving antenna, you can see the effect transmission characteristics of changing the edge length using transmission line connecting the '''Apply''' button. Click OK receiving antenna to close the dialogreceiver circuit and the receiver chain parameters.
Note that unlike EM.Cube's other computational modules that express the default mesh density based on the wavelengthIn a simple link scenario, the resolution of the SBR mesh generator received power P<sub>r</sub> in dBm is expressed in project length units. The default edge length value of 100 units might be too large for non-flat objects. You may have to use a lower value to capture found from the curvature of your curved structures adequately. following equation:
<math> P_r [dBm] = P_t [File:prop_manual-29.png]dBm]+ G_{TC} + G_{TA} - PL + G_{RA} + G_{RC} </math>
Figure 1: [[Propagation Module]]'s Mesh Settings dialogwhere P<sub>t</sub> is the baseband signal power in dBm at the transmitter, G<sub>TC</sub> and G<sub>RC</sub> are the total transmitter and receiver chain gains in dB, respectively, G<sub>TA</sub> and G<sub>RA</sub> are the total transmitting and receiving antenna gains in dB, respectively, and PL is the channel path loss in dB. Keep in mind that EM.Terrano is fully polarimetric. The transmitting and receiving antenna characteristics are specified through the imported radiation pattern files, which are part of the definition of the transmitters and receivers. In particular, the polarization mismatch losses are taken into account through the polarimetric SBR ray tracing analysis.
If you specify the noise-related parameters of your receiver set, the signal-to-noise ratios (SNR) is calculated at each receiver location: SNR === Special Discretized Object Types ===P<sub>r</sub> - P<sub>n</sub>, where P<sub>n</sub> is the noise power level in dB. When planning, designing and deploying a communication system between points A and B, the link is considered to be closes and a connection established if the received signal power at the location of the receiver is above the noise power level by a certain threshold. In other words, the SNR at the receiver must be greater than a certain specified minimum SNR level. You specify (SNR)<sub>min</sub> ss part of the definition of receiver chain in the Receiver Set dialog. In the "Visualization Options" section of this dialog, you can also check the check box labeled '''Generate Connectivity Map'''. This is a binary-level black-and-white map that displays connected receivers in white and disconnected receivers in black. At the end of an SBR simulation, the computed SNR is displayed in the Receiver Set dialog for the selected receiver. The connectivity map is generated and added to the navigation tree underneath the received power coverage map node.
In EM.CubeAt the end of an SBR simulation, terrain objects are represented by you can visualize the field maps and saved as special "Tessellated" objects with quadrilateral cells. This is true receiver power coverage map of terrain objects that you create yourself using EMyour receiver sets.CubeA coverage map shows the total 's Terrain Generator as well as all ''Received Power''' by each of the terrain objects that you import from external files to your projectreceivers and is visualized as a color-coded intensity plot. The center of Under each cell represents receiver set node in the terrain elevation at that point. Tessellated objects navigation tree, a total of seven field maps together with a received power coverage map are considered as discretized objects by EMadded.Cube The field maps include amplitude and they are not meshed one more time by phase plots for the SBR mesh generator. Each quadrilateral cell is divided into two triangular cells before being passed to the SBR simulation engine. Thereforethree X, when using EMY, Z field components plus a total electric field plot.Cube's Terrain Generator to create To display a new terrain objectfield or coverage map, you have to pay special attention to simply click on its entry in the resolution of navigation tree. The 3D plot appears in the terrain object Main Window overlaid on your propagation scene. A legend box on the right shows the color scale and units (dB). The 3D coverage maps are displayed as it determines horizontal confetti above the total number receivers. You can change the appearance of terrain facets sent to the simulation enginereceivers and maps from the property dialog of the receiver set. A high resolution terrain, although looking better You can further customize the settings of the 3D field and more realistic, may easily lead to an enormous computational problemcoverage plots.
You can use EM<table><tr><td>[[Image:AnnArbor Scene1.Cube's "Polymesh" tool to discretize solid and surface CAD objectspng|thumb|left|640px|The downtown Ann Arbor propagation scene. You can manually control the mesh characteristics ]]</td></tr><tr><td>[[Image:AnnArbor Scene2.png|thumb|left|640px|The electric field distribution map of polymesh objects including inserting new nodes on faces the Ann Arbor scene with vertical dipole transmitter and edges or deleting existing nodesreceivers. In addition, EM]]</td></tr><tr><td>[[Image:AnnArbor Scene3.Cube's Solid Generator png|thumb|left|640px|The received power coverage map of the Ann Arbor scene with vertical dipole transmitter and Surface Generator tools create ploymesh solids and surfaces, respectivelyreceivers. Like tessellated object, polymesh objects are also considered as discretized objects by EM]]</td></tr><tr><td>[[Image:AnnArbor Scene4.Cube and they are not meshed again by png|thumb|left| 640px |The connectivity map of the Ann Arbor scene with SNR<sub>min</sub> = 3dB with the basic color map option.]]</td></tr><tr><td>[[Image:AnnArbor Scene5.png|thumb|left| 640px |The connectivity map of the Ann Arbor scene with SNR<sub>min</sub> = 20dB with the SBR mesh generatorbasic color map option. ]]</td></tr></table>
=== SBR Mesh Rules & Considerations === Coming Soon... === Adjusting Block Elevation On Terrain === In EM.Cube, buildings and all other CAD objects are initially created on Visualizing the XY plane by default. In other words, the Z-coordinate of the local coordinate system (LCS) of all blocks is set to zero until you change them. As long as you use the global ground, all is fine as your buildings are seated on the ground. When your propagation scene has an irregular terrain, you want to place your buildings on the terrain and not buried under it. Buildings Rays in EM.Cube are not adjusted to the terrain elevation automatically. You need to instruct EM.Cube to do so. To update the building positions and adjust their elevation to the underlying terrain, right click on the '''Terrain''' item of the Navigation Tree and select '''Adjust Scene Elevation''' from the context menu. All the blocks in the scene are automatically elevated in the Z direction such that their bases sit on the terrain. In effect, all the blocks are translated along the global Z axis by proper amounts such that their local Z coordinate equals the Z-elevation of the underlying terrain object. This feature is particularly useful if you change the location of the terrain or import a new terrain after the blocks have been created. Note: You have to make sure that the resolution of your terrain, its fluctuation scale and building dimensions are all comparable. Otherwise, on a high-resolution, rapidly varying terrain, you will have buildings whose bottoms are in contact with the terrain only at a few points and parts of them hang in the air. [[File:prop_adjust1_tn.png]] [[File:prop_adjust2_tn.png]] A Scene with Buildings and Terrain Before and After Adjusting Elevation === Transmitters & Receivers Above An Irregular Terrain === In EM.Cube, all the transmitters and receivers are tied up with point objects in the project workspace. These point objects are grouped and organized in base sets. When you move the point objects or change their coordinates, all of their associated transmitters or receivers immediately follow them to the new location. For example, you usually define a grid of receivers using a base set that is made up of a uniformly spaced array of points and spread them in your scene. All of these receivers have the same height because their associated base points all have the same Z-coordinate. When your receivers are located above a flat terrain like the global ground, their Z-coordinates are equal to their height above the ground, as the terrain elevation is fixed and equal to zero everywhere. The same is true for transmitters, too.  In many propagation modeling problems, your transmitters and receivers may be located above an irregular terrain with varying elevation across the scene. In that case, you may want to place your transmitters or receivers at a certain height above the underlying ground. The Z-coordinate of a transmitter or receiver is now the sum of the terrain elevation at the base point and the specified height. EM.Cube gives you the option to adjust the transmitter and receiver sets to the terrain elevation. This is done for individual transmitter sets and individual receiver sets. At the top of the Transmitter Dialog there is a check box labeled "'''Adjust Tx Sets to Terrain Elevation'''". Similarly, at the top of the Receiver Dialog there is a check box labeled "'''Adjust Rx Sets to Terrain Elevation'''". These boxes are unchecked by default. As a result, your transmitter sets or receiver sets coincide with their associated base points in the project workspace. If you check these boxes and place a transmitter set or a receiver set above an irregular terrain, the transmitters or receivers are elevated from the location of their associated base points by the amount of terrain elevation as can be seen in the figure below.  To better understand why there are two separate sets of points in the scene, note that a point array (CAD object) is used to create a uniformly spaced base set. The array object always preserves its grid topology as you move it around the scene. However, the transmitters or receivers associated with this point array object are elevated above the irregular terrain and no longer follow a strictly uniform grid. If you move the base set from its original position to a new location, the base points' topology will stay intact, while the associated transmitters or receivers will be redistributed above the terrain based on their new elevations. [[File:prop_txrx1_tn.png]] [[File:prop_txrx2_tn.png]] Figure 1: Transmitters and receivers adjusted above an uneven terrain and their associated base sets.  == Running A SBR Simulation == EM.Cube's [[Propagation Module]] offers three types of ray tracing simulations: * Analysis* Frequency Sweep* Parametric Sweep An SBR analysis is the simplest ray tracing simulation and involves the following steps: # Set the unit of project scene and the frequency of operation. Note that EM.Cube's default project unit is millimeter. When working with the [[Propagation Module]], pay attention to the project unit. Radio propagation problems usually require meter, mile or kilometer as the project unit.# Create the blocks and draw the buildings at the desired locations.# Keep the default ray domain and accept the default global ground or change its material properties.# Define the base sets (at least one for the transmitter and one for the receiver).# Define the transmitter and receiver(s) using the available base sets.# Run the SBR simulation engine.# Visualize the coverage map and plot other data. You can access the [[Propagation Module]]'s run dialog by clicking the '''Run''' [[File:run_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Simulate > Run...''' or using the keyboard shortcut '''Ctrl+R'''. When you click the '''Run''' button, a new window opens up that reports the different stages of the SBR simulation and indicates the progress of each stage. After the SBR simulation is successfully completed, a message pops up and prompts the completion of the process. [[File:PROP12.png]] Figure 1: [[Propagation Module]]'s Simulation Run dialog. === SBR Simulation Parameters === There are a number of SBR simulation settings that can be accessed and changed from the SBR Settings Dialog. To open this dialog, click the button labeled '''Settings''' on the right side of the '''Select Engine''' dropdown list in the Run Dialog. EM.Cube's SBR simulation engine allows you to separate the physical effects that are calculated during a ray tracing process. You can selectively enable or disable '''Ray Reflection''', '''Ray Transmission''' and '''Ray Diffraction'''. By default, all three effects are checked and included in the computations. Separating these effects sometimes help you better analyze your propagation scene and understand the impact of various blocks in the scene. EM.Cube requires a finite number of ray bounces for each original ray emanating from a transmitter. This is very important in situations that may involve resonance effects where rays get trapped among certain group of surfaces and may bounce back and forth indefinitely. This is set using the box labeled "'''Max No. Ray Bounces'''", which has a default value of 10. Note that the maximum number of ray bounces directly affects the computation time as well as the size of output simulation data files. This can become critical for indoor propagation scenes, where most of the rays undergo a large number of reflections.  As rays travel in the scene and bounce from surfaces, they lose their power and their amplitudes diminish. From a practical point of view, only rays that have power above the receiver sensitivity threshold can be effectively received. Therefore, all the rays whose power fall below a specified power threshold are discarded. The '''Ray Power Threshold''' is specified in dBm and has a default value of -100dBm. Keep in mind that the value of this threshold directly affects the accuracy of the simulation results as well as the size of the output data file. You can also set the '''Angular Resolution''' of the transmitter rays in degrees. By default, every transmitter emanates equi-angular ray tubes at a resolution of 1 degree. Lower angular resolutions larger than 1° speed up the SBR simulation significantly, but they may compromise the accuracy. Higher angular resolutions less than 1° increase the accuracy of the simulating results, but they also increase the computation time. [[File:PROP13.png]] Figure 1: [[Propagation Module]]'s SBR Engine Settings dialog. === The Coverage Map === If the associated radiator set is isotropic, so will be the transmitter set. By default, an isotropic transmitter has vertical polarization. You can use the '''Polarization''' radio button to select one of the two options: '''Vertical''' or '''Horizontal'''. If the associated radiator set consists of '''Short Dipole''' or '''User Defined''' radiators, it is indicated in the transmitter property dialog. In the case of a short dipole radiator, you can set a value for the dipole current in Amperes. The radiation resistance of a short dipole of length ''dl'' is given by: [[File:eqngr6.png]] The radiated power of a short dipole carrying a current I<sub>0</sub> is then given by: [[File:shortdipole.png]] For isotropic and user defined radiators you can set the '''Input Power''' and '''Phase''' of a transmitter set in Watts and degrees, respectively. This can be accessed from the '''Transmitter Chain''' dialog, which will be described in detail in the next section. The radiation pattern of the associated radiator set is normalized and used in conjunction with the input power value to create a weighted distribution of transmitted rays. In certain cases like hybrid simulations, you may want to use the actual values of the far field to define the transmitter power rather than a normalized radiation pattern. Note that the pattern (.RAD) file contains the value of total radiated power in its header. In this case, check the box labeled '''"Calculate Power From Radiation Pattern"'''. This is calculated directly from the complex θ and φ components of the far field data by integrating them over the entire space (4π solid angle). Note that this option is available only when the radiator is of the User Defined type. When this box is checked, the transmitter chain button is grayed out. By default, an isotropic transmitter emanates rays uniformly in all directions at the angular resolution specified by the user. A transmitter with a user defined associated radiator may represent a highly directional radiation pattern with the main beam pointing in a certain direction. You can additionally force and limit the '''Angular Extents''' of rays to a certain solid angle around the transmitter. This is especially useful and computationally efficient when the transmitter is on one side of the scene, and all the scatterers and receivers are on the other side. In this case, there is no need to generate rays in all directions. To limit the angular extents of rays, define the Start and End values for both Theta (θ) and Phi (φ) angles. The value of the angular resolution of the rays can be changed from the Run Dialog as will be discussed later. In a regular SBR simulation, you have a transmitter and one or more arrays of receivers in your scene. At the end of the simulation, you can visualize the coverage map of the transmitter over the receiver sets. A coverage map shows the total '''Received Power''' by each of the receivers and is visualized as a color-coded intensity plot. You can visualize the coverage maps of individual receiver sets. At the end of a SBR simulation, each Received Power Coverage Map is listed under the receiver set's name in the Navigation Tree. To display a coverage map, simply click on its entry in the Navigation Tree. The coverage map plot appears in the Main Window overlaid on the scene. A legend box on the right shows the color scale and units (dB). The 3-D coverage maps are displayed as horizontal confetti above the receivers. If the receivers are packed close to each other, you will see a continuous confetti map. If the receivers are far apart, you will see individual colored squares. You can also visualize coverage maps as colored 3-D cubes. This may be useful when you set up your receivers in a vertical arrangement or the scene has a highly uneven terrain. To change the type of coverage map visualization, open the receiver set's property dialog and select the desired option for '''Coverage Map: Confetti''' or '''Cube''' in the '''"Visualization Options"''' section of the dialog. [[File:prop_run11_tn.png]] [[File:prop_run12_tn.png]] Received power coverage map: (Left) confetti style, and (Right) cube style. You can change the settings of the coverage map by right clicking on its entry in the Navigation Tree and selecting '''Properties...''' or by double-clicking on the legend box. In the Output Plot Settings dialog, you can choose from one of three Color Map options: '''Default''', '''Rainbow''' and '''Grayscale'''. The visualization plot uses default values for the color scale. In the section titled "Limits", you can choose the radio button labeled '''User Defined'''. Then, you have to enter new values for the '''Lower''' and '''Upper''' Limits of the plot. You can also show or hide the Legend Box or change its '''Background''' and '''Foreground''' colors by clicking the buttons provided for this purpose. [[File:prop_run4.png]] Output Plot Settings === The Ray Data ===
At the end of a SBR simulation, each receiver receives a number of rays. Some receivers may not receive any rays at all. You can visualize all the rays received by a certain receiver from the active transmitter of the scene. To do this, right click the '''Receivers''' item of the Navigation Tree. From the context menu select '''Show Received Rays'''. All the rays received by the currently selected receiver of the scene are displayed in the scene. The rays are identified by labels, are ordered by their power and have different colors for better visualization. You can display the rays for only one receiver at a time. The receiver set property dialog has a list of all the individual receivers belonging to that set. To display the rays received by another receiver, you have to change the '''Selected Receiver''' in the receiver set's property dialog. If you keep the mouse focus on this dropdown list and roll your mouse scroll wheel, you can scan the selected receivers and move the rays from one receiver to the next in the list. To remove the visualized rays from the scene, right click the Receivers item of the Navigation Tree again and from the context menu select '''Hide Received Rays'''.
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[[File:prop_run5_tn.png]]
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Visualization of received rays at the location of the selected receiver.
You can also view the ray parameters by opening the property dialog of a receiver set. By default, the first receiver of the set is always selected. You can select any other receiver from the drop-down list labeled '''Selected Receiver'''. If you click the button labeled '''Show Ray Data''', a new dialog opens up with a table that contains all the received rays at the selected receiver and their parameters:
* Ray Power is the received power at the receiver due to a specific ray and is given in dBm.
* Angles of Arrival are the θ and φ angles of the incoming ray at the local spherical coordinate system of the receiver.
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[[Image:UrbanCanyon17.png|thumb|left|720px|EM.Terrano's ray data dialog showing a selected ray.]]
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The Ray Data Dialog also shows the '''Total Received Power''' in dBm and '''Total Received Field''' in dBV/m due to all the rays received by the receiver. You can sort the rays based on their delay, field, power, etc. To do so, simply click on the grey column label in the table to sort the rays in ascending order based on the selected parameter. You can also select any ray by clicking on its '''ID''' and highlighting its row in the table. In that case, the selected rays is highlighted in the Project Workspace and all the other rays become thin (faded).
{{Note: The |All the received rays are summed up coherently in a vectorial manner at the receiverlocation.}}
<table><tr><td> [[FileImage:prop_run6_tnUrbanCanyon18.png|thumb|left|640px|Visualization of received rays at the location of a selected receiver in the random city scene.]]</td></tr></table>
Analyzing a selected ray from the ray data dialog. === Plotting Other Simulation Results === Besides visualizing the coverage map and received rays in the EM.CUBE's [[Propagation Module]], you can also plot the '''Path Loss''' of all the receivers belonging to a receiver set as well as the '''Power Delay Profile''' of individual receivers. To plot these data, go the '''Observables''' section of the Navigation Tree and right click on the '''Receivers''' item. From the context menu, select '''Plot Path Loss''' or '''Plot Power Delay Profile''', respectively. The path loss data between the active transmitter and all the receivers belonging to a receiver set are plotted on a Cartesian graph. The horizontal axis of this graph represents the index of the receiver. Power Delay Profile is a bar chart that plots the power of individual rays received by the currently selected receiver versus their time delay. If there is a line of sight (LOS) between a transmitter and receiver, the LOS ray will have the smallest delay and therefore will appear first in the bar chart. Sometimes you may have several rays arriving at a receiver at the same time, i.e. all with the same delay, but with different power level. These will appear as stacked bars in the chart. You can also plot the path loss and power delay profile graphs and many others from EM.CUBE's data manager. You can open data manager by clicking the '''Standard Output Data Manager''' [[File:data_manager_icon.png]] button of the '''Compute Toolbar''' or by selecting '''Compute [[File:larrow_tn.png]] Data Manager''' from the menu bar or by right clicking on the '''Data Manager''' item of the Navigation Tree and selecting Open Data Manager... from the contextual menu or by using the keyboard shortcut '''Ctrl+D'''. In the Data manager Dialog, you will see a list of all the data files available for plotting. These include the theta and phi angles of arrival and departure of the selected receiver. You can select any data file by clicking and highlighting its '''ID''' in the table and then clicking the '''Plot''' button. === Output Data Files ===
At the end of an SBR simulation, EM.Terrano writes a number of ASCII data files to your project folder. The main output data file is called "sbr_results.RTOUT". This file contains all the information about individual receivers and the parameters of each ray that is received by each individual receiver.
At the end of an SBR simulation, the results are written into a main output data file with the reserved name of SBR_Results.RTOUT. This file has the following format:
NEW LINEEach receiver line has the following information:
* Receiver NumberID* Receiver Base X, Y , Z Coordinatescoordinates* Receiver HeightTotal received power in dBm* Total number of received rays
NEW LINEEach rays line received by a receiver has the following information:
Number of Rays NEW LINE:* Ray Index* Ray NumberDelay in nsec
* θ and φ Angles of Arrival in deg
* θ and φ Angles of Departure in deg
* Delay in nsec* Real(and imaginary parts of the three E<supsub>Vx</supsub>) & Imag(, E<sup>V</sup>)* Real(E<sup>H</sup>) & Imag(E<sup>H</sup>)* Real('''E.e<sub>Ry</sub>''') & Imag(''', E.e<sub>Rz</sub>''')components* Number of ray hit points * PowerCoordinates of individual hit points
The angles of arrival are the θ and φ angles of a received ray measured in degrees and are referenced in the local spherical coordinate systems centered at the location of the receiver. The angles of departure for a received ray are the θ and φ angles of the originating transmitter ray, measured in degrees and referenced in the local spherical coordinate systems centered at the location of the active transmitter, which eventually arrives at the receiver. The total time delay is measured in nanoseconds between t = 0 nsec at the time of launch from the transmitter location till being received at the receiver location. The last four columns show the real and imaginary parts of the received electric fields with vertical and horizontal polarizations, respectively. The complex field values are normalized in a way that when their magnitude is squared, it equals the received ray power. If the active transmitter is an isotropic radiator with either a vertical or horizontal polarization, then the field components corresponding to the other polarization will have zero entries in the output data file.
<table><tr><td> [[FileImage:prop_run8_tn.png|800pxthumb|left|720px|A typical SBR output data file.]]</td></tr></table>
Figure: A typical SBR output data file.=== Plotting Other Simulation Results ===
=== Running A Frequency Sweep With SBR ===Besides "sbr_results.out", [[EM.Terrano]] writes a number of other ASCII data files to your project folder. You can view or plot these data in [[EM.Cube]]'s Data Manager. You can open data manager by clicking the '''Data Manager''' [[File:data_manager_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Menu > Simulate > Data Manager''' from the menu bar or by right-clicking on the '''Data Manager''' item of the navigation tree and selecting '''Open Data Manager...''' from the contextual menu or by using the keyboard shortcut {{key|Ctrl+D}}.
By default, you run a single-frequency simulation The available data files in EM.CUBE's [[Propagation Module]]. You set the operational frequency "2D Data Files" tab of a SBR simulation in the project's '''Frequency Dialog''', which can be accessed in a number of waysData Manger include:
# By clicking the * '''FrequencyPath Loss''' [[File:freq_iconThe channel path loss is defined as PL = P<sub>r</sub> - EIRP.png]] button The path loss data are stored in a file called "SBR_receiver_set_name_PATHLOSS.DAT" as a function of the '''Compute Toolbar'''receiver index. The path loss data make sense only if your receiver set has the default isotropic radiator.# By selecting * '''ComputePower Delay Profile''' [[File:larrow_tnThe delays of the individual rays received by the selected receiver with respect to the transmitter are expressed in ns and tabulated together with the power of each ray in the file "SBR_receiver_set_name_DELAY.png]]'''Frequency SettingsDAT"...''' You can plot these data from the Menu BarData Manager as a bar chart called the power delay profile.# Using The bars indeed correspond to the keyboard shortcut difference between the ray power in dBm and the minimum power threshold level in dBm, which makes them a positive quantity. * '''Ctrl+FAngles of Arrival'''.# By double clicking : These are the frequency section (box) Theta and Phi angles of the '''Status Bar'''individual rays received by the selected receiver and saved to the files "SBR_receiver_set_name_ThetaARRIVAL.<br /> ANG" and "SBR_receiver_set_name_PhiARRIVAL.ANG". You can plot them in the Data Manager in polar stem charts.
When you run a frequency or parametric sweep in [[File:prop_freqEM.pngTerrano]] , a tremendous amount of data may be generated. [[File:prop_run10EM.pngTerrano]]only stores the '''Received Power''', '''Path Loss''' and '''SNR''' of the selected receiverin ASCII data files called "PREC_i.DAT", "PL_i.DAT" and "SNR_i.DAT", where is the index of the receiver set in your scene. These quantities are tabulated vs. the sweep variable's samples. You can plot these files in EM.Grid.
(Left) Project[[Image:Info_icon.png|40px]] Click here to learn more about working with data filed and plotting graphs in [[EM.Cube]]'s frequency dialog and (Right) the frequency settings dialog'''[[Defining_Project_Observables_%26_Visualizing_Output_Data#The_Data_Manager | Data Manager]]'''.
You can also select the '''Frequency Sweep''' option in the '''Simulation Mode''' drop-down list of the '''Run Dialog'''<table><tr><td> [[Image:Terrano pathloss. Click the '''Settings...''' button on the right side png|thumb|360px|Cartesian graph of this dropdown list to open up the Frequency Settings Dialogpath loss. Based on the original values of the project center frequency and bandwidth, the '''Start Frequency''' and '''End Frequency''' have default values]] </td><td> [[Image:Terrano delay. You can also change the '''Number png|thumb|360px|Bar graph of Samples'''power delay profile. Once you click the '''Run''' button, EM]] </td></tr><tr><td> [[Image:Terrano ARR phi.CUBE performs a frequency sweep by assigning each png|thumb|360px|Polar stem graph of Phi angle of the frequency samples as the current operational frequency and running the SBR simulation engine at that frequencyarrival. All the simulation data at all frequency samples are saved into the output data files including "SBR_results.RTOUT"]] </td><td> [[Image:Terrano ARR theta. After the completion png|thumb|360px|Polar stem graph of a frequency sweep simulation, as many coverage maps as the number Theta angle of frequency samples are generated and added to the Navigation Tree under the Receiver Set's entryarrival. You can click on each ]] </td></tr><tr><td> [[Image:Terrano DEP phi.png|thumb|360px|Polar stem graph of the coverage maps corresponding to each Phi angle of the frequency samples and visualize it in the project workspacedeparture. You can also animate the coverage maps]] </td><td> [[Image:Terrano DEP theta. To do so, right click on the receiver set's name in the Navigation Tree and select '''Animation''' from the contextual menu. The coverage maps start to animate by their order on the Navigation Tree. Once the entire list is displayed sequentially, it starts all over again from the beginning png|thumb|360px|Polar stem graph of the list. During the animation, the '''Animation Controls''' dialog appears at the lower right corner Theta angle of the screendeparture. This dialog has a number of buttons for pause]] </resume, step forwardtd></backward, and step to the endtr></start. The title of each coverage map is shown in the box labeled '''Sample''' as it is displayed in the main window. You can also change the speed of animation. The default frame duration has a value of 300 (3x100) milliseconds. To stop the animation, simply press the keyboard's '''Esc Key'''.table>
[[File:prop_run13.png]] [[File:prop_run14.png]]=== Visualizing 3D Radiation Patterns of Transmit and Receive Antennas in the Scene ===
Multiple coverage maps on When you designate a "User Defined Antenna Pattern" as the Navigation Tree radiator type of a transmitter set or a receiver set, EM.Terrano copies the imported radiation pattern data file from its original folder to the current project folder. The name of the ".RAD" file is listed under the '''3D Data Files''' tab of the data manager. Sometimes it might be desired to visualize these radiation patterns in your propagation scene at the end actual location of the transmitter or receiver. To do so, you have to define a frequency sweep new '''Radiation Pattern''' observable in the navigation tree. The label of the new observable must be identical to the name of the ".RAD" data file. In addition, the Theta and starting an animation from Phi angle increments of the new radiation pattern observable (expressed in degrees) must be identical to the Theta and Phi angular resolutions of the imported pattern file. If all these conditions are met, then go to the '''Simulate Menu''' and select the item '''Update All 3D Visualization'''. The contents of the 3D radiation patterns are added to the navigation tree. Click on one of the radiation pattern items in the navigation tree and it will be displayed in the contextual menuscene.
<table><tr><td>[[FileImage:prop_run15_tnUrbanCanyon6.png|thumb|left|640px|The received power coverage map of the random city scene with a highly directional dipole array transmitter.]]</td></tr></table>
Animation controls By Default, [[EM.Cube]] always visualizes the 3D radiation patterns at the origin of coordinates, i.e. at (0, 0, 0). This is because that radiation pattern data are computed in the standard spherical coordinate system centered at (0, 0, 0). The theta and phi components of the far-zone electric fields are defined with respect to the X, Y and Z axes of this system. When visualizing the 3D radiation pattern data in a propagation scene, it is more intuitive to display the pattern at the location of the transmitter or receiver. The Radiation Pattern dialog allows you to translate the pattern visualization to any arbitrary point in the project workspace. It also allows you to scale up or scale down the pattern visualization with respect to the background scene.
=== Running In the example shown above, the imported pattern data file is called "Dipole_Array1.RAD". Therefore, the label of the radiation pattern observable is chosen to be "Dipole_Array1". The theta and phi angle increments are both 1° in this case. The radiation pattern has been elevated by 10m to be positioned at the location of the transmitter and a Parametric Sweep with SBR ===scaling factor of 0.3 has been used.
In EM<table><tr><td>[[Image:UrbanCanyon8.CUBE, all png|thumb|left|640px|Setting the CAD object properties as well as certain source, material and mesh pattern parameters can be assigned as [[variablesin the radiation pattern dialog.]]. </td></tr></table><table><tr><td>[[Variables]] are defined to control and vary Image:UrbanCanyon7.png|thumb|left|720px|Visualization of the values 3D radiation pattern of such parameters either for editing purposes or to run parametric sweep or [[optimization]]the directional transmitter in the random city scene. Variable are defined using the '''[[Variables]] Dialog''', which can be accessed in the three ways:</td></tr></table>
# By clicking There is an important catch to remember here. When you define a radiation pattern observable for your project, EM.Terrano will attempt to compute the '''[[Variables]]''' [[File:variable_icon.png]] button overall effective radiation pattern of the '''Compute Toolbar'''entire physical structure.# By selecting However, in this case, you defined the radiation pattern observable merely for visualization purposes. To stop EM.Terrano from computing the actual radiation pattern of your entire scene, there is a check box in EM.Terrano's Ray Tracer Simulation Engine Settings dialog that is labeled ''Compute'Do not compute new radiation patterns'' [[File:larrow_tn.png]] '''[[Variables]].This box is checked by default, which means the actual radiation pattern of your entire scene will not be computed automatically.But you need to remember to uncheck this box if you ever need to compute a new radiation pattern using EM.Terrano''' from the Menu Bar.# Using the keyboard shortcut '''Ctrl+B'''s SBR solver as an asymptotic EM solver (see next section).
The <table><tr><td>[[variables]] dialog is initially emptyImage:UrbanCanyon9. To add a new variable, click the png|thumb|left|640px|EM.Terrano'''Add''' button to open up the '''Add Variable/Syntax Dialog'''. In this s Run Simulation dialog you have to type in a name for the new variable and choose a type. The default type is '''Uniformly Spaced Samples'''. You also need to specify the '''Start''', '''Stop''' and '''Step''' values for the variable. In the figure below, a variable called "Tx_Height" is defined that varies between 2 and 10 with equal steps of 2. This means the sample set {2,4,6,8,10}. When you return to the [[variables]] dialog, the syntax of the new variable is shown as 2:10:2. The last number in this syntax is always the variable step. In this example, this variable is going to be used to control the height of the transmitter in a propagation scene.</td></tr></table>
[[File:prop_run24== Using EM.png]] [[File:prop_run23.png]]Terrano as an Asymptotic Field Solver ==
Like every other electromagnetic solver, EM.CUBETerrano's variable dialog SBR ray tracer requires an excitation source and one or more observables for the dialog generation of simulation data. EM.Terrano offers several types of sources and observables for defining a new variableSBR simulation. You already learned about the transmitter set as a source and the receiver set as an observable. You can mix and match different source types and observable types depending on the requirements of your modeling problem.
Next, you have to attach the variable to the CAD object. In this case, the CAD object is the point object that represents the transmitter's radiator. To attach a variable to a CAD object, open the object's property dialog and type The available source types in the name of the variable as the value of a property or parameterEM. In this case, the variable Tx_Height is going to control the Z-Coordinate of the point object. Once the value of the object parameter is replaced by the name of an already defined variable, it is updated with the current value of that variable. In the case of a variable of "Uniformly Spaced Samples" type, the current value is the start value. This value will be incrementally varied during a parametric sweep simulation process. Note that a variable can take a fixed value or a discrete set of values, too. You can always open the [[variables]] dialog and change the value or syntax of any variable. To make a new or modified value effective, click the '''Apply''' button of the [[variables]] dialog. You can test the values by performing a '''Dry Run''' of the selected variable. This runs an animation of the project workspace as the value of the variable changes and all the related CAD objects Terrano are updated accordingly. Note that you can attach the same variable to more than one CAD object property or to the properties of different objects. You can also define multiple values or syntaxes to the same variable. To do so, open the '''Add Variable/Syntax Dialog''', and instead of typing in a new variable name, choose an existing variable name from the '''Name''' dropdown list. This will add a new value or syntax to the existing syntax(es) of the selected variable. When you return to the [[variables]] dialog, [[variables]] with more than one value or syntax will have a dropdown list in the '''Syntax''' column. You can choose any of these values or syntaxed at any time and make the change effective by clicking the '''Apply''' button.:
{| class="wikitable"|-! scope="col"| Icon! scope="col"| Source Type! scope="col"| Applications! scope="col"| Restrictions|-| style="width:30px;" | [[File:prop_run25transmitter_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Point Transmitter Set | Point Transmitter Set]]| style="width:250px;" | Modeling realsitic antennas & link budget calculations| style="width:250px;" | Requires to be associated with a base location point set|-| style="width:30px;" | [[File:hertz_src_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Hertzian Short Dipole Source | Hertzian Short Dipole]]| style="width:250px;" | Almost omni-directional physical radiator| style="width:250px;" | None, stand-alone source|-| style="width:30px;" | [[File:huyg_src_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Materials, Sources, Devices & Other Physical Object Types#Huygens Source | Huygens Source]]| style="width:250px;" | Used for modeling equivalent sources imported from other [[EM.Cube]] modules | style="width:250px;" | None, stand-alone source imported from a Huygens surface data file|}
Replacing Click on each type to learn more about it in the value [[Glossary of a CAD object parameter EM.Cube's Materials, Sources, Devices & Other Physical Object Types]]. Â The available observables types in [[EM.Terrano]] are:Â {| class="wikitable"|-! scope="col"| Icon! scope="col"| Source Type! scope="col"| Applications! scope="col"| Restrictions|-| style="width:30px;" | [[File:receiver_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Simulation Observables & Graph Types#Point Receiver Set | Point Receiver Set]]| style="width:250px;" | Generating received power coverage maps & link budget calculations| style="width:250px;" | Requires to be associated with a variable namebase location point set|-| style="width:30px;" | [[File:Distr Rx icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Simulation Observables & Graph Types#Distributed Receiver Set | Distributed Receiver Set]]| style="width:250px;" | Computing received power at a receiver characterized by Huygens surface data| style="width:250px;" | None, stand-alone source imported from a Huygens surface data file|-| style="width:30px;" | [[File:fieldsensor_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Simulation Observables & Graph Types#Near-Field Sensor Observable | Near-Field Sensor]]| style="width:250px;" | Generating electric and magnetic field distribution maps| style="width:250px;" | None, stand-alone observable|-| style="width:30px;" | [[File:farfield_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Simulation Observables & Graph Types#Far-Field Radiation Pattern Observable | Far-Field Radiation Pattern]]| style="width:250px;" | Computing the effective radiation pattern of a radiator in the presence of a large scattering scene | style="width:250px;" | None, stand-alone observable|-| style="width:30px;" | [[File:huyg_surf_icon.png]]| style="width:150px;" | [[Glossary of EM.Cube's Simulation Observables & Graph Types#Huygens Surface Observable | Huygens Surface]]| style="width:250px;" | Collecting tangential field data on a box to be used later as a Huygens source in other [[EM.Cube]] modules| style="width:250px;" | None, stand-alone observable|}
To run a parametric sweep, open the '''Run Dialog''' and select the '''Parametric Sweep''' option Click on each type to learn more about it in the '''Simulation Mode''' drop-down list. If you have not defined any [[variables]] in the project, the box in the Glossary of EM.Cube'''[[Variabless Simulation Observables & Graph Types]]''' row before the '''View''' will be red. You have to turn it into green before When you can run define a simulationfar-field observable in EM. By clicking the '''View''' buttonTerrano, you can open up the [[variables]] dialog from here. Once you click the '''Run''' buttona collection of invisible, EM.CUBE performs a parametric sweep by incrementally varying isotropic receivers are placed on the values surface of all the defined [[variables]] from their start to stop values at the specified steps a large sphere that encircles your propagation scene and updating all the related CAD of its geometric objects. After These receivers are placed uniformly on the completion of spherical surface at a parametric sweep simulationspacing that is determined by your specified angular resolutions. In most cases, as many coverage maps as the total number you need to define angular resolutions of variable samples are generated and added to at least 1° or smaller. Note that this is different than the Navigation Tree under the receiver settransmitter rays's entryangular resolution. You can click on each may have a large number of transmitted rays but not enough receivers to compute the coverage maps effective radiation pattern at all azimuth and visualize it in the project workspaceelevation angles. You can also animate the coverage maps sequentially. To do so, right click on the receiver set's name Also keep in the Navigation Tree mind that with 1° Theta and select '''Animation''' from the contextual menu. To stop the animationPhi angle increments, simply press the keyboard's '''Esc Key'''you will have a total of 181 × 361 = 65,341 spherically placed receivers in your scene.
{{Note| Computing radiation patterns using EM.Terrano's SBR solver typically takes much longer computation times than using [[FileEM.Cube]]'s other computational modules.}} <table><tr><td> [[Image:prop_run26SBR pattern.png|thumb|540px|Computed 3D radiation pattern of two vertical short dipole radiators placed 1m apart in the free space at 1GHz.]]</td></tr></table>
Choosing parametric sweep as the simulation mode in the run dialog. Note that one variable has been defined and EM.CUBE is ready to run the simulation.== Statistical Analysis of Propagation Scene ==
[[File:prop_run27_tnEM.Terrano's coverage maps display the received power at the location of all the receivers. The receivers together from a set/ensemble, which might be uniformly spaced or distributed across the propagation scene or may consist of randomly scattered radiators. Every coverage map shows the '''Mean''' and '''Standard Deviation''' of the received power for all the receivers involved. These information are displayed at the bottom of the coverage map's legend box and are expressed in dB.png]]
The When you run either a frequency sweep or a parametric sweep simulation in EM.Terrano, you have the option to generate two additional coverage map maps: one for the mean of all the scene at individual sample coverage maps and another for their standard deviation. To do so, in the end '''Run Dialog''', check the box labeled '''"Create Mean and Standard Deviation received power coverage maps"'''. Note that the mean and standard deviation values displayed on the individual coverage maps correspond to the spatial statistics of a parametric sweep where the receivers in the scene, while the mean and standard deviation coverage maps show the statistics with respect to the frequency or other sweep variable is sets at each point in the transmitter heightsite. Also, note that both of the mean and standard deviation coverage maps have their own spatial mean and standard deviation values expressed in dB at the bottom of their legend box.
=== Statistical Analysis of Propagation Scene ===<table><tr><td> [[Image:PROP MAN12.png|thumb|left|480px|EM.Terrano's simulation run dialog showing frequency sweep as the simulation mode along with statistical analysis.]] </td></tr></table>
EM<table><tr><td> [[Image:UrbanCanyon4.CUBE's png|thumb|left|640px|The mean coverage maps display the received power map at the location end of all the receiversa frequency sweep. The receivers together from a set]] </ensemble, which might be uniformly spaced or distributed across the propagation scene or may consist of randomly scattered radiatorstd></tr><tr><td> [[Image:UrbanCanyon5. Every png|thumb|left|640px|The standard deviation coverage map shows the '''Mean''' and '''Standard Deviation''' of the received power for all the receivers involved. These information are displayed at the bottom end of the coverage map's legend box and are expressed in dBa frequency sweep.]] </td></tr></table>
In the [[Propagation Module]], when you ran a sweep simulation (frequency, transmitter or parametric), you also have the option to generate two additional coverage maps: one for the mean of all the individual sample coverage maps and another for their standard deviation. To do so, in the '''Run Dialog''', check the box labeled '''"Create Mean and Standard Deviation Coverage Maps"'''. Note that the mean and standard deviation values displayed on the individual coverage maps correspond to the spatial statistics of the receivers in the scene, while the mean and standard deviation coverage maps correspond to frequency, transmitter or variable sets defined for the sweep simulation. Also, note that both of the mean and standard deviation coverage maps have their own spatial mean and standard deviation values expressed in dB at the bottom of their legend box.<br />
[[File:prop_run21_tn.png]]<hr>
The mean coverage map at [[Image:Top_icon.png|30px]] '''[[EM.Terrano#Product_Overview | Back to the end Top of a transmitter sweep.the Page]]'''
[[FileImage:prop_run22_tnTutorial_icon.png|30px]]'''[[EM.Cube#EM.Terrano_Documentation | EM.Terrano Tutorial Gateway]]'''
The standard deviation coverage map at the end of a transmitter sweep[[Image:Back_icon.png|30px]] '''[[EM.Cube | Back to EM.Cube Main Page]]'''