How to model a via though an infinite ground plane between two dielectric layers

In IE3D, I have a feed structure on one layer, with a via penetrating an infinite ground plane to feed an antenna on a second layer on the opposite side. As far as I understand, there are two methods of modelling the effects of the aperture or void in the ground plane through which the feed/via passes, but do not know how to physically model them?? Any help will be gratefully received!