EM.Cube's Propagation Module allows you to define block groups of each of the above three types. Each block group has the same color or texture and its members share the same material properties: permittivity ε<sub>r</sub> and conductivity Ï. Also, all the penetrable surfaces belonging to the same block group have the same wall thickness. You can define many different block groups with certain properties and underneath each introduce many member objects with different geometrical shapes and dimensions. The table below summarizes the characteristics of each block type:
<table><tbody><tr {| class="oddwikitable"><td align|-! scope="leftcol">'''| Block Type'''</td><td align! scope="leftcol">'''|Physical Effects'''</td><td align! scope="leftcol">'''|Admissible Object Types'''</td></tr>|-<tr class="even"><td align="left">| Impenetrable Surface</td><td align="left">| Reflection, Diffraction</td><td align="left">| All Solid & Surface CAD Objects</td></tr>|-<tr class="odd"><td align="left">| Penetrable Surface</td><td align="left">| Reflection, Diffraction, Transmission</td><td align="left">| All Solid & Surface CAD Objects</td></tr>|-<tr class="even"><td align="left">| Terrain Surface</td><td align="left">| Reflection</td><td align="left">| Tessellated Objects Only</td></tr></tbody></table>|}
== Impenetrable Surfaces For Outdoor Scenes ==