CST & Boundary effects

Hello
If you have a patch antenna in CST, you must apply the boundaries to the antenna sides, bottom and top.
The bottom (ground plane) is an electric plane (Et=0) the top is open (add space).
BUT the sides are named open. My question is, will CST exstend the materials (substrate, ground plane) that close up to these boundaries to infinity? I mean will it extend the substrate and ground plane to infinity?
Hope it makes sense.
Thank you

Hello tyassin,
The bottom boundary is Et=0, so E-fields are calculated only in the upper hemisphere. If you'll check the farfields you will see that nothing is radiated "backwards". The substrate and the ground plane are not extended beyond the calculation box in this case (This happens in periodic BC).
Regards,
P.