HFSS interdigitated capacitor

Hi,

I am very new to HFSS. I am trying to simulate an inter digitated capacitor on a wafer. So far I have just created the geometry in HFSS (Please find the file attached). Could anyone please tell me how to excite the capacitor ?

Thanks.

I believe, it is useless to excite an interdigital capacitor alone. It is always a part of some kind of waveguide, microstrip or coplanar. Create a microstrip or coplanar line, then excite it with a waveport, or lumped port (2-port pass-through model), as you like.
Then I would simulate input sections of the transmission line, and extract them from the ABCD matrix of the whole model to see the capacitor properties (using matlab).

In a circuit of lumped elements... Heh, I don't know. Maybe you should recreate that part of the circuit with the ground, get the ground and two signal points for two lumped ports.
And don't forget the air box. The fields in lumped capacitor are leaking out like in coplanar line. So there should be some space above the substrate; and boundaries set for that space.