Changes

Import of shapefiles and STEP, IGES abnd and STL CAD model files for scene construction</li>

Python-based wizards for generation of parameterized multi-story office bulidings buildings and several terrain scene types</li>

Standard half-wave dipole transmitters and receivers orinted oriented along the principal axes</li>

Statistical analsyis analysis of the propagation scene</li>

| style="width:250px;" | Only point, cube box and sphere objects

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 the types of physical phenomena that are used to model their interaction with the impinging rays. EM.Terrano discretizes geometric objects into a number of flat facets. The field intensity, phase and power of the reflected and transmitted rays depend on the material properties of the obstructing facet. The specular surface of a facet can be modeled locally as a simple homogeneous dielectric half-space or as a multilayer medium. In that respect, all the obstructing objects such as buildings, walls, terrain, etc. behave in a similar way:

[[Image:PROP MAN2.png|thumb|left|720px|An urban propagation scene generated by EM.Terrano's "Random City" wizardand "Basic Link" wizards. It consists of 25 cubic brick buildings, one transmitter and a large two-dimensional array of receivers. ]]

#Half-wave dipole oriented along one of the the three principal axes

#Half-wave dipole oriented along one of the the three principal axes

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.Terrano gives you three options for the radiator associated with a point transmitter: * Half-wave dipole* Orthogonally polarized isotropic radiators* User defined antenna pattern  By default, EM.Terrano assumes that your transmitter is a vertically polarized (Z-directed) resonant half-wave resonant dipole antenna. This antenna has an almost omni-directional radiation pattern in all azimuth directions. It also has radiation nulls along the axis of the dipole. You can change the direction of the dipole and orient it along the X or Y axes using the provided drop-down list. The second choice of two orthogonally polarized isotropic radiators is an abstract source that is used for polarimetric channel characterization as will be discussed later.  You can override the default radiator option and select any other kind of antenna with a more complicated radiation pattern. For this purpose, you have to import a radiation pattern data file to EM.Terrano. You can model any radiating structure using [[EM.Cube]]'s other computational modules, [[EM.Tempo]], [[EM.Picasso]], [[EM.Libera]] or [[EM.Illumina]], and generate a 3D radiation pattern data file for it. The far-field radiation patter data are stored in a specially formatted file with a &quot;'''.RAD'''&quot; file extension. This file contains columns of spherical &phi; and &theta; angles as well as the real and imaginary parts of the complex-valued far-zoned zone electric field components '''E_&theta;''' and '''E_&phi;'''. The &theta;- and &phi;-components of the far-zone electric field determine the polarization of the transmitting radiator.

A transmitter set always needs to be associated with an existing base location set with one or more point objects in the project workspace. Therefore, you cannot define a transmitter for your scene before drawing a point object under a base location set.

Once you define a new transmitter set, its name is added in the '''Transmitters''' section of the navigation tree. The color of all the base points associated with the newly defined transmitter set changes, and an additional little ball with the transmitter color (red by default) appears at the location of each associated base point. You can open the property dialog of the transmitter set and modify a number of parameters including the '''Baseband Source Power''' in Watts and the broadcast signal '''Phase''' in degrees. The default transmitter power level is 1W or 30dBm. There is also a check box labeled '''Use Custom Input Power''', which is checked by default. In that case, the power and phase boxes are enabled and you can change the default 1W power and 0&deg; phase values as you wish. [[EM.Cube]]'s ".RAD" radiation pattern files usually contain the value of &quot;Total Radiated Power&quot; in their file header. This quantity is calculated based on the particular excitation mechanism that was used to generate the pattern 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.

Receivers act as observables in a propagation scene. The 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. However, unlike EM.Terrano gives you three options for the transmitter caseradiator associated with a point receiver set: * Half-wave dipole* Polarization matched isotropic radiator* User defined antenna pattern  By default, EM.Terrano assumes that your receiver, by default, is an isotropic radiatora vertically polarized (Z-directed) resonant half-wave dipole antenna. You can change the direction of the dipole and orient it along the X or Y axes using the provided drop-down list. An isotropic radiator has a perfect omni-directional radiation pattern in all azimuth and elevation directions. An isotropic radiator doesn't physically exist physically in the real world. But the assumption of a default, polarization-matched, isotropic receiver is but it can be used simply as a convenient choice point in space to generate received power coverage maps of a propagation scenecompute the electric field.  You might may also define a complicated radiation pattern for your receiver set. In that case, you need to import a radiation pattern data file to EM.Terrano. Note that you can simply use similar to the data file "DPL_STD.RAD" for that purpose, which is also used by EM.Terrano for the definition case of the default vertical half-wave dipole a transmitterset.

Similar to transmitter sets, you define a receiver set by associating it with an existing base location set with one or more point objects in the project workspace. All the receivers belonging to the same receiver set have the same radiator type. 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 an array of points as your base location set.

Once you define a new receiver set, its name is added in to the '''Receivers''' section of the navigation tree. The color of all the base points associated with the newly defined receiver set changes, and an additional little ball with the receiver color (yellow by default) appears at the location of each associated base point. You can open the property dialog of the receiver set and modify a number of parameters.

If you choose the "user defined antenna" option for your receiver set, it will indeed consist consists of a basic "Super-Heterodyne Receiver Chain" that starts with contains a receive antenna, which is used connected via a segment of transmission line to capture the broadcast signal from the free space, and it ultimately ends low-noise amplifier (LNA) that is terminated in a baseband/IF signalmatched load. The receiverset's property dialog allows you to define a the basic super-heterodyne 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 Low-Noise Amplifier (LNA), mixer such as its gain and baseband/IF amplifier including stage gains and impedance mismatch factors (IMF) 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. You also need to enter values for the '''Noise Figure''' of various active devices in the receiver chain. 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.

[[EM.Terrano]]'s Transmitter Set dialog and Receiver Set dialog both allow you to rotate an imported radiation pattern. In that case, you need to specify the '''Rotation''' angles in degrees about the X-, Y- and Z-axes. It is important to note that these rotations are performed sequentially and in the following order: first a rotation about the X-axis, then a rotation 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-axis transforms the XYZ LCS to a new primed X^&prime;Y^&prime;Z^&prime; LCS. The second rotation is performed with respect to the new Y^&prime;-axis and transforms the X^&prime;Y^&prime;Z^&prime; LCS to a new double-primed X^{&prime;&prime;}Y^{&prime;&prime;}Z^{&prime;&prime;} LCS. The third rotation is finally performed with respect to the new Z^{&prime;&prime;}-axis. The figures below shows single and double rotations.

<td> [[File:PROP22B.png|thumb|200px300px|The local coordinate system of a linear dipole antenna.]] </td><td> [[File:PROP22C.png|thumb|370px600px|Rotating the dipole antenna by +90&deg; about the local Y-axis.]] </td>

<td> [[File:PROP22D.png|thumb|600px720px|Rotating the dipole antenna by +90&deg; about the local X-axis and then by -45&deg; by the local Y-axis.]] </td>

When your transmitters or 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. 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.Terrano]] 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 &quot;'''Adjust Tx Sets to Terrain Elevation'''&quot;. Similarly, at the top of the Receiver Dialog there is a check box labeled &quot;'''Adjust Rx Sets to Terrain Elevation'''&quot;. 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.

=== The SBR SolverRay Tracing Solvers's Output Simulation Data ===

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 large number of rays from the transmitters and 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.Terrano's Channel 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 an SBR a ray tracing simulation, all the polarimetric rays emanating from the transmitter(s) or other sources that are received by the individual receivers are computed, collected, sorted and savedinto ASCII data files. From the ray data, the 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, the ray's elevation and azimuth angles of departure and arrival (departure from the transmitter location and arrival at the receiver location), and time delay of the received ray with respect to the transmitter. If you specify the temperaturetemperatures, noise figure levels and transmission line losses in the definition of the receiver sets, the noise power level and signal-to-noise ratios ratio (SNR) at each receiver are also calculated, and so are the E_b/N₀ and bit error rate (BER) for the selected digital modulation scheme.

The In a simple link scenario, the received power P_r in dBm is found from the following equation:

[[Image:Terrano L6 Fig4AnnArbor Scene1.png|thumb|left|640px|The downtown Ann Arbor propagation scene.]]

[[Image:Terrano L6 Fig16AAnnArbor Scene2.png|thumb|left|640px|The electric field distribution map of the Ann Arbor scene with super-heterodyne vertical dipole transmitter and receivers.]]

[[Image:Terrano L6 Fig16AnnArbor Scene3.png|thumb|left|640px|The received power coverage map of the Ann Arbor scene with super-heterodyne vertical dipole transmitter and receivers.]]

[[Image:Terrano L6 Fig17AnnArbor Scene4.png|thumb|left| 640px |The connectivity map of the Ann Arbor scene with SNR_min = 25dB 3dB with Rainbow 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_min = 20dB with the basic color map option.]]

[[Image:Ray dialogUrbanCanyon17.png|thumb|left|720px|EM.Terrano's ray data dialogshowing a selected ray.]]

<td> [[Image:Terrano L6 Fig16BUrbanCanyon18.png|thumb|left|640px|Visualization of received rays at the location of a selected receiver in the downtown Ann Arbor random city scene.]] </td>

=== The Standard Output Data Files File ===

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.

== Discretizing the Propagation Scene in EM.Terrano == === Why Do You Need to Discretize the Scene? === [[EM.Terrano]]'s SBR solver uses a method known as Geometrical Optics (GO) in conjunction with the Uniform Theory of Diffraction (UTD) to trace the rays from their originating point at the source to the individual receiver locations. Rays may hit obstructing objects on their way and get reflected, diffracted or transmitted. [[EM.Terrano]]'s SBR solver can only handle diffraction off linear edges and reflection from and transmission through planar interfaces. When an incident ray hits the surface of the obstructing object, a local planar surface assumption is made at the specular point. The assumptions of linear edges and planar facets are valid in in the case of a scene with cubic buildings and a flat global ground.  In many practical scenarios, however, your buildings may have curved surfaces, or the terrain may be irregular. [[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 lot of subtleties like these must be taken into account by the SBR solver to run accurate and computationally efficient simulations.  === Generating the SBR Mesh === You can view and examine the discretized version of your scene objects as they are sent to the SBR simulation engine. You can adjust the mesh resolution and increase the geometric fidelity of discretization by creating more and finer triangular facets. On the other hand, you may want to reduce the mesh complexity and send to the SBR engine only a few coarse facets to model your buildings. The resolution of [[EM.Terrano]]'s facet mesh generator is controlled by the '''Mesh Cell Size''' 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 mesh cell size in [[EM.Terrano]]'s Mesh Settings dialog, along with a lower curvature angle tolerance value to capture the curvature of your curved structures adequately. <table><tr><td> [[Image:prop_manual-29.png|thumb|left|480px|EM.Terrano's mesh settings dialog.]] </td></tr></table> [[Image:Info_icon.png|30px]] Click here to learn more about '''[[Preparing_Physical_Structures_for_Electromagnetic_Simulation#Working_with_EM.Cube.27s_Mesh_Generators | Working with Mesh Generator]]'''. [[Image:Info_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]]'''. <table><tr><td> [[Image:PROP MAN9.png|thumb|left|640px|The facet mesh of the buildings in the urban propagation scene generated by EM.Terrano's Random City wizard.]] </td></tr></table> == Running SBR Simulations in EM.Terrano == === SBR Simulation Types === 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. [[EM.Terrano]] offers thee simulation modes:  {| class="wikitable"|-! scope="col"| Simulation Mode! scope="col"| Usage! scope="col"| Number of Engine Runs! scope="col"| Frequency ! scope="col"| Restrictions|-| style="width:120px;" | [[#Running a Single-Frequency SBR Analysis | Single-Frequency Analysis]]| style="width:250px;" | Simulates the propagation scene "As Is"| style="width:100px;" | Single run| style="width:150px;" | Runs at the center frequency fc| style="width:100px;" | None|-| style="width:120px;" | [[Parametric_Modeling_%26_Simulation_Modes_in_EM.Cube#Running_Frequency_Sweep_Simulations_in_EM.Cube | Frequency Sweep]]| style="width:250px;" | Varies the operating frequency of the ray tracer | style="width:100px;" | Single ray tracing run, multiple frequency computations | style="width:150px;" | Runs at a specified set of frequency samples| style="width:100px;" | None|-| style="width:120px;" | [[Parametric_Modeling_%26_Simulation_Modes_in_EM.Cube#Running_Parametric_Sweep_Simulations_in_EM.Cube | Parametric Sweep]]| style="width:250px;" | Varies the value(s) of one or more project variables| style="width:100px;" | Multiple runs| style="width:150px;" | Runs at the center frequency fc| style="width:100px;" | None|} You set the simulation mode in [[EM.Terrano]]'s simulation run dialog. A single-frequency analysis is a single-run simulation. The two other simulation modes in the above list are considered multi-run simulations. If you run a simulation without having defined any observables, no data will be generated at the end of the simulation. In multi-run simulation modes, certain parameters are varied and a collection of simulation data files are generated. At the end of a sweep simulation, you can graph the simulation results in EM.Grid or you can animate the 3D simulation data from the navigation tree.  {{Note| [[EM.Terrano]]'s frequency sweep simulations are very fast because the geometrical optics (ray tracing) part of the simulation is frequency-independent.}} === Running a Single-Frequency SBR Analysis === A single-frequency SBR analysis is the simplest type of ray tracing simulation and involves the following steps: * 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. You can access [[EM.Terrano]]'s Simulation Run dialog by clicking the '''Run''' [[File:run_icon.png]] button of the '''Simulate Toolbar''' or by selecting '''Simulate &gt; 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. <table><tr><td> [[Image:Terrano L1 Fig16.png|thumb|left|480px|EM.Terrano's simulation run dialog.]] </td></tr></table> <table><tr><td> [[Image:PROP MAN10.png|thumb|left|550px|EM.Terrano's output message window.]] </td></tr></table> === Changing the SBR Engine Settings === 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 {{key|Settings}} on the right side of the '''Select Engine''' 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, the reflection, transmission and edge diffraction effects are enabled and the terrain diffraction effects are disabled. Separating these effects sometimes help you better analyze your propagation scene and understand the impact of various blocks in the scene. [[EM.Terrano]] allows 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 multiple surfaces and may bounce back and forth indefinitely. This is set using the box labeled &quot;'''Max No. Ray Bounces'''&quot;, 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. Two other parameters control the diffraction computations: '''Max Wedge Angle''' in degrees and '''Min Edge Length''' in project units. The maximum wedge angle is the angle between two conjoined facets that is considered to make them almost flat or coplanar with no diffraction effect. The default value of the maximum wedge angle is 170&deg;. The minimum edge length is size of the common edge between two conjoined facets that is considered as a mesh artifact and not a real diffracting edge. The default value of the minimum edge length is 5 project units.  <table><tr><td> [[Image:PROP MAN11.png|thumb|left|720px|EM.Terrano's SBR simulation engine settings dialog.]] </td></tr></table> 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 threshold can be effectively received. Therefore, all the rays whose power levels 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. The SBR Engine Settings dialog also shows the required '''Minimum Angular Resolution''' in degrees in a greyed-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. === Statistical Analysis of Propagation Scene ===

[[EM.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.

When you run either a frequency sweep or a parametric sweep simulation in [[EM.Terrano]], you 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 '''&quot;Create Mean and Standard Deviation Coverage Mapsreceived power coverage maps&quot;'''. 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 show the statistics with respect to the frequency or other sweep variable sets at each point in the site. 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.

[[Image:Terrano L4 Fig21UrbanCanyon4.png|thumb|left|640px|The mean coverage map at the end of a frequency sweep.]]

[[Image:Terrano L4 Fig22UrbanCanyon5.png|thumb|left|640px|The standard deviation coverage map at the end of a frequency sweep.]]