[[Image:Info_icon.png|40px]] Click here to learn more about '''[[Hybrid_Modeling_using_Multiple_Simulation_Engines#Generating_Huygens_Surface_Data | Generating Huygens Surface Data]]'''.
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=== Using EM.Terrano as a Field Solver ===
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The simplest SBR simulation can be performed using a short dipole source with a specified field sensor plane. As an asymptotic EM solver, EM.Terrano then computes the electric and magnetic fields radiated by your dipole source in the presence of your multipath propagation environment. EM.Terrano's short dipole source and field sensor observable are very similar to those of [[EM.Cube]]'s other computational modules. You can also compute the far field radiation patterns of a dipole in the presence of surrounding scatterers or compute the Huygens surface data for use in [[EM.Cube]]'s other modules.
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[[Image:Info_icon.png|40px]] Click here to learn more about using EM.Terrano as an '''[[Asymptotic Field Solver]]'''.
=== Defining Transmitter Sets ===
<td> [[Image:prop_txrx1_tn.png|thumb|400px|Transmitter (red) and receivers (yellow) adjusted above an uneven terrain surface.]] </td>
<td> [[Image:prop_txrx2_tn.png|thumb|400px|The underlying base point sets (blue and orange dots) associated with the adjusted transmitters and receivers on the terrain.]] </td>
</tr>
</table>
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== Using EM.Terrano as a Field Solver ==
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The simplest SBR simulation can be performed using a short dipole source with a specified field sensor plane. As an asymptotic EM solver, EM.Terrano then computes the electric and magnetic fields radiated by your dipole source in the presence of your multipath propagation environment. EM.Terrano's short dipole source and field sensor observable are very similar to those of [[EM.Cube]]'s other computational modules. You can also compute the far field radiation patterns of a dipole in the presence of surrounding scatterers or compute the Huygens surface data for use in [[EM.Cube]]'s other modules.
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[[Image:Info_icon.png|40px]] Click here to learn more about using EM.Terrano as an '''[[Asymptotic Field Solver]]'''.
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== Defining a Hertzian Dipole Source ==
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[[File:PROP18(1).png|thumb|350px|EM.Terrano's Short Dipole Source dialog.]]
A short dipole is the simplest way of exciting a structure in [[EM.Terrano]]. It is also the closest thing to an omnidirectional radiator. The direction or orientation of the short dipole determines its polarization. Note that [[EM.Terrano]] does not offer an isotropic radiator as a source type because it is a polarimetric ray tracer. A short dipole source acts like an infinitesimally small ideal current source.
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To define a short dipole source, follow these steps:
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* Right click on the '''Short Dipoles''' item in the '''Sources''' section of the Navigation Tree and select '''Insert New Source...''' from the contextual menu. The Short Dipole dialog opens up.
* In the '''Source Location''' section of the dialog, you can set the coordinate of the center of the short dipole. By default, the source is placed at the origin of the world coordinate system at (0,0,0). You can type in new coordinates or use the spin buttons to move the dipole up from the default global ground.
* In the '''Source Properties''' section, you can specify the '''Amplitude''' in Amperes, the '''Phase''' in degrees as well as the '''Length''' of the dipole in project units.
* In the '''Direction Unit Vector''' section, you can specify the orientation of the short dipole by setting values for the components '''uX''', '''uY''', and '''uZ''' of the dipole's unit vector. The default values correspond to a vertical (Z-directed) short dipole. The dialog normalizes the vector components upon closure even if your component values do not satisfy a unit magnitude.
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The radiation resistance of a short dipole of length ''dl'' is given by:
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:<math> R_r = 80\pi^2 \left( \frac{dl}{\lambda_0} \right)^2 </math>
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The radiated power of a short dipole carrying a current I<sub>0</sub> is then given by:
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:<math> P_{rad} = \frac{1}{2} R_r |I_0|^2 = 40\pi^2 |I_0|^2 \left( \frac{dl}{\lambda_0} \right)^2 </math>
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== Defining a Field Sensor ==
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[[File:PROP18(2).png|thumb|350px|EM.Terrano's Field Sensor dialog]]
As an asymptotic electromagnetic field solver, the SBR simulation engine can compute the electric and magnetic field distributions in 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.
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In the section titled Output Settings, you can also select the field map type from two options: '''Confetti''' and '''Cone'''. The former produces an intensity plot for field amplitude and phase, while the latter generates a 3D vector plot. In the confetti case, you have an option to check the box labeled '''Data Interpolation''', which creates a smooth and blended (digitally filtered) map. In the cone case, you can set the size of the vector cones that represent the field direction. At the end of a sweep simulation, multiple field map are produced and added to the Navigation Tree. You can animate these maps. However, during the sweep only one field type is stored, either the E-field or H-field. You can choose the field type for multiple plots using the radio buttons in the section titled '''Field Display - Multiple Plots'''. The default choice is the E-field.
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Once you close the Field Sensor dialog, its name is added under the '''Field Sensors''' node of the Navigation Tree. 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.
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[[Image:MORE.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#Visualizing_3D_Near-Field_Maps | Visualizing 3D Near Field Maps]]'''.
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<table>
<tr>
<td> [[Image:PROP18M.png|thumb|450px|Computed total electric field distribution of a vertical short dipole radiator 2m above the default global ground at 1GHz.]] </td>
<td> [[Image:PROP18N.png|thumb|450px|Computed total magnetic field distribution of a vertical short dipole radiator 2m above the default global ground at 1GHz.]] </td>
</tr>
</table>
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== Computing Radiation Patterns In SBR ==
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[[File:PROP18(3).png|thumb|350px|EM.Terrano's Radiation Pattern dialog.]]
[[EM.Terrano]] lets you compute the effective far-field radiation pattern of your radiating structure in the presence of surrounding scatterers and obstructing objects. Computing the radiation pattern of an antenna or any radiating structure in [[EM.Cube]]'s full-wave computational modules like [[EM.Tempo]], [[EM.Picasso]] or [[EM.Libera]] is fairly straightforward. Using [[EM.Illumina]] you can use an asymptotic physical optics solver to model the effects of the mounting platform on the performance of an installed antenna. Computing radiation patterns in [[EM.Terrano]] may not seem intuitive at first because you have to import the radiation patterns from external data files after all.
In order to visualize a radiation pattern in [[EM.Terrano]], you have to define a "Far Fields" observable. To do so, right-click on the '''Far Fields''' item in the '''Observables''' section of the navigation tree and select '''Insert New Radiation Pattern...''' from the contextual menu. This opens up the Radiation Pattern dialog. You can accept most of the default settings. The most important [[parameters]] to change are the angular resolutions. These are called '''Theta Angle Increment''' and '''Phi Angle Increment''', both of which have default values of 5°. When you define a far-field observable in [[EM.Terrano]], a collection of <u>invisible</u>, isotropic receivers are placed on the surface of a large sphere that encircles your propagation scene and all of its objects. These receivers are equally spaced on the spherical surface at a spacing that is determined by your specified angular resolutions. In most cases, you need to define angular resolutions of at least 1° or smaller. Note that this is different than the transmitter rays' angular resolution. You may have a large number of transmitted rays but not enough receivers to compute the effective radiation pattern at all 3D angles. Also keep in mind that with 1° Theta and Phi angle increments, you will have a total of 181 × 361 = 65,341 spherically placed receivers in your scene.
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{{Note| Computing radiation patterns using [[EM.Terrano]]'s SBR solver typically takes much longer computation times than using [[EM.Cube]]'s other computational modules.}}
[[Image:MORE.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#Visualizing_3D_Radiation_Patterns | Visualizing 3D Radiation Patterns]]'''.
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[[Image:MORE.png|40px]] Click here to learn more about '''[[Data_Visualization_and_Processing#2D_Radiation_and_RCS_Graphs | Plotting 2D Radiation Graphs]]'''.
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<table>
<tr>
<td> [[Image:PROP18P.png|thumb|450px|Computed 3D radiation pattern of two vertical short dipole radiators placed 1m apart in the free space at 1GHz.]] </td>
</tr>
</table>