Designing an antenna with two ports in HFSS 15.0

I am designing an antenna with two ports (1.Co-axial feed & 2. CPW feed) in HFSS 15.0.
Can anyone please tell that how do I simulate it & how do I get the results for separate ports?

You'll analyze it as a three-port, two feed-lines and the radiation interface, results in a respective set of s-prarameters,

In the general case, part of the energy fed to one port will return on the other port. I wonder what's the purpose of the design?