There is no s-paramaters involved if you need to include plane wave. On IE3D and FIDELITY, you can define N-ports and planewave excitation with both E and H-polarizations simultaneously. After simulation, you will get the N-port s-parameters. Besides, you will get a general pattern. From the general pattern, you can define a polarization of planewave (any combination of E and H or even circular pol), and you can find the V and I on the ports. It can't be done on MGRID in post processing mode or PATTERNVIEW.