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 its objects at any time.
Â
[[Image:PROP15.png|thumb|400px|EM.Terrano's Domain Settings dialog.]]
=== Computational Domain & Global Ground ===
Â
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 green wireframe box 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.
Â
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. You can change them arbitrarily. After changing these values, use the '''Apply''' button to make the changes effective while the dialog is still open.
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:
Â
# Click the '''Domain''' [[File:image025.jpg]] button of the Simulation Toolbar.
# Select the '''Simulate''' > '''Computational Domain''' > '''Settings...''' item of the Simulate Menu.
# Right click on the '''Ray Domain''' item of the Navigation Tree and select '''Domain Settings...'''
# Use the keyboard shortcut '''Ctrl + A'''.
Â
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 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. '''Do not forget to disable the global ground if you want to model a free space propagation scene.'''
Â
[[File:PROP4.png]]
Â
Figure 2: [[Propagation Module]]'s Global Ground Settings dialog.
=== Buildings & Obstructing Blocks ===
You can construct several thin walls and arrange them as rooms. A regular room can be built by placing four vertical wall objects together with an optional horizontal wall at the top for the ceiling. Alternatively, you may use [[EM.Cube]]'s hollow box objects or boxes with one or two capped end(s). '''Keep in mind that all the penetrable surfaces belonging to a group have the same wall thickness, which is initially set to 0.5 project units by default. Also, 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.
Â
=== Computational Domain & Global Ground ===
Â
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:
Â
# Click the '''Domain''' [[File:image025.jpg]] button of the Simulation Toolbar.
# Select the '''Simulate''' > '''Computational Domain''' > '''Settings...''' item of the Simulate Menu.
# Right click on the '''Ray Domain''' item of the Navigation Tree and select '''Domain Settings...'''
# Use the keyboard shortcut '''Ctrl + A'''.
Â
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. You can change them arbitrarily. After changing these values, use the '''Apply''' button to make the changes effective while the dialog is still open.
Â
[[File:PROP15.png]]
Â
Figure 1: [[Propagation Module]]'s Domain Settings dialog.
Â
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 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. '''Do not forget to disable the global ground if you want to model a free space propagation scene.'''
Â
[[File:PROP4.png]]
Â
Figure 2: [[Propagation Module]]'s Global Ground Settings dialog.
=== Terrain Surfaces vs. Global Ground ===