HFSS and Zpi (Modeiling a cap)

Hey,
I'm trying to model the true impedance of a 2.44pf ceramic cap where the RF trace does not completely cover the full surface area of the cap.

I know I can do this using an integration line and calculating Zpi, but I'm definitely doing it wrong. I am using a waveport that has the same shape of my trace, but I thought I would be able to create an integration line that goes INTO the cap not tangent to the metalized plate.

Any help and suggestions are very much welcome.

If you post your structure here, the problem could be understood better..

This is what I am trying to model and I am pretty sure this is very wrong.

Thanks

The lumped port has to go from the cap (lower edge) to the ground surface (PerfE in your model) not just from the top edge of the cap to the lower one.

Also, I think you would have to apply radiation boundary onto the air box.

For the results (I don't exactly know, what you're looking for... but): it does not make sense to plot Z in the Smith chart. There you normally plot the reflection, meaning s11 - otherwise the point is outside the unit circle.

The Z you can see by right-clicking on the results, opening the matrix data and checking the Z box.