I am currently working on a reconfigurable UWB MIMO antenna. I used momentum to run EM simulation for my matching network. I have a finite ground for each antenna and I defined ports for each SMD elements connection points( only for one of the antenna. I used a single port for the other antenna). I labeled the port right after the first antenna as port1 and port 2 for the 2nd antenna. I found out I have different S11 and S22( antennas are identical). Whenever I remove the ports I defined for SMD elements, I get exactly same S11 and S22. I am guessing this is a common(reference) ground problem and I do not know how to solve it. I attached my workspace and I am hoping someone can help me.