How to simulate loop antenna in HFSS

Hi,
I am new to HFSS. I have a loop antenna and i am trying to get S-parameters of this atenna. After placing the PORTs and run the simulation it is aborted due to no terminals are attached to PORT. If i assign terminals to ports they it is saying more than one conductor for terminal. Kindly help me. the antenna drawing attached for your reference.

Thank you,

A ports requires signal and ground reference. If you place a port on each end of the loop, where do the port ground references go?

If you have no ground near your loop, then the loop is simulated as a 1-port with lumped port (+) and (-) between the two ends of the loop. Only then, current can flow.

Hi,
Thank you for reply,
With putting differential port also it is not solving. Ok please guide me to create a project and draw the antenna and get S parameters of the above mentioned antenna. My antenna is 300X400 mm with 70 micron thick micro strip loop antenna. And i want to simulate it at 4 MHz.