Hi tomtom,
thanks for your reply. you raise a point about a ground, which is what I have been wondering about actually.
My structure is very simple to explain in words. Its just a single loop that I created by sweeping a circle. However the loop is not closed (swept only like 355 degrees) so the loop ends are not joined together. My goal is to excite this loop with a 50ohm coax, so I can find inductance from the mismatch of the 50ohm coax and the impedance of my loop inductor. Specifically, L=im(Z11)/w.
I'm not sure where I would put a ground such as a plane with PEC boundary condition with infinite ground checked. In real life, my loop would just exist by itself with no physical ground plane near by (unlike structures like CPW's that have an explicit ground plane in fabrication).
Currently, my setup is as follows: I have only one coax for this simulation, and it extends all the way to a radiation box wall like you suggested. I have one loop end attached to my PEC coax probe, and the other loop end attached to the PEC coax outer conductor. The reason I did this is because I view coax stimulation as the input field going through the coax inner conductor into one of the loop ends. Then the other loop end is connected to the outer conductor, which I deem "ground" to close the current path. But I don't think this is quite right. I've also tried using two coaxes, one for each end so I have two waveports. But for this I don't know how to have any "ground" in my design.
I appreciate your suggestions