Symmetry Boundary (PMC/PEC) in HFSS - Pattern Problems

pmc hfss

Hello everyone,

I am simulating a patch antenna that has H-plane symmetry. It is operating in the lowest mode. I get excellent impedance matching results for S11, but my radiation pattern (co-pol and x-pol) for both principal planes is not accurate when compared to the antenna simulated without the symmetry plane. Does anyone know why this might be? Is there something I need to do to tell HFSS to properly calculate the radiation pattern when using a symmetry plane?

Alternatively, if someone could link me or upload an example or tutorial as to how I should properly set up a symmetry plane, it would be greatly appreciated. Note that I DID use the impedance multiplier of 0.5 and set the port to solve Zpv.

Thank you in advance!

pmc boundary symmetry

hi

well i havent used HFSS that much but all i can say is you need to make sure that your antenna is symmetric with respect to your chosen symmetry planes os more specifically w.r.t your excitation port

i hope it helps

regards

hfss symmetry boundary conditions

Hello shahid78,

It understand that . The patch antenna I am simulating has H-plane symmetry, so I was using a PMC symmetry plane to cut it in half.

It turns out that the scale was off on my graphs, as I had a -300 dB null at broadside on the x-pol at broadside for the H-plane, so that was distorting the graph. Silly me for not looking at the scale . My H-plane co-pol and x-pol now match the results I got for the patch without the PMC boundary.

The E-plane, however, has a slight problem. The co-pol is fine, but the x-pol is computed to be zero when using the symmetry boundary. It is definitely not zero, and the original model predicts it to be, while small, about -60 dB. Then again, when the x-pol is this small, who cares, right? I have a feeling this might have to do with boundary conditions. Nevertheless, if there is a way around this, it would be nice to compute the x-pol for the E-plane as it may be significant for other designs. Does anyone have any ideas?

I attached my models here.

Thanks in advance!

I checked the HFSS design you posted.
I don't see how with this antenna geometry you can utilize an E-plane for symmetry purposes ....
Electric field will always be parallel to the symmetry plane, so you can only use an H-plane symmetry plane.
Otherwise, I have misunderstood something.