hello all,

I use IE3D to do my patch simulation.
Recently I did a test where I simulated a simple patch antenna (it was at about 1GHz) and looked at the 3D radiation pattern, I saw that the pattern is ending at the XY plane where the field is ZERO, than I changed the first layer so it won't be a metal strip and drew a new ground plane, the simulation result where almost the same. and now for the surprise: I added a thick layer of air under the ground plane (hoping it will help me get a pattern at the negative Z direction) and what I got is a better Gain result! (over 1 dB better) and still no radiation to the -Z direction.

Can anyone help me understand why? why the results were better with a thick air layer under the ground, and more important why or how I can get a radiation resault in the -Z direction.

(for port I used the "probe to patch" option with the ground plane as negative and the patch as the positive).

10x
Sag.