HFSS current loop -- one waveport or two?

Hi,

If I want to simulate a current loop (single turn either by sweeping a circle or multiple turns by using helix generator function), how many waveports should I have?

Should I have one coax whose probe attaches to one end of the loop, and another coax for the second end of loop?

Or one loop end connecting to a coax's probe, and the other loop end connecting to the outer conductor of the same coax? In other words, just use one coax.

In either case, I'm at lost to where my "ground" will be.

thanks,