coplanar waveguide ppt
Don't know about HFSS as I haven't sat down to learn it yet, but in momentum, and designer/ensemble, CPW is handled by defining an infinite ground plane and drawing slots for the gaps between the signal and gound traces. In momentum place the ports at the edges of the slots you just drew (you can enable edge & midpoint snaps to help with this) and then use the port editor to define them as coupled.
Alternatively, if you want a finite ground trace you could draw the ground-signal-ground traces on a regular trace layer, place six ports on the structure and, again using the port editor, define the two ports attached the signal trace as internal ports while setting the other four ports to be ground references for the signal ports in their respective planes. The simulator will give 2-port S-parameters with this setup.
I guess it would be possible to setup a finite ground cpw structure in designer/ensemble as well with a similar setup as momentum except that you can't define a ground reference for both ground traces. You can't setup ground reference at all in ensemble (stand alone product), as far as I know. I suppose that you can simulate the structure and take the 6-port data back into the circuit simulator and connect the ground ports together and use that node as the reference node for the signal port. Just spitballing here, haven't really tried this to see if it would work since I'm able to get what I want done between momentum and sonnet.
Iknow you didn't ask for the designer/ensemble information, but thought it might help anyone else reading the thread that had designer/ensemble instead of momentum, or at the very least start some healthy discussion. After all thats what these boards are for, right?