I am trying to design a u-slot aperture coupled patch antenna in millimeter-wave band (about 30 GHz) using CST and according to the picture attached.
I have a few problems in the procedure:
1- I can not find "foam" in CST material library so I think I should make a new material myself. But the problem is that only the εr of foam is mentioned in papers. Nothing is mentioned about tgσ and other parameters required for defining foam. How should I do that?
2- I do not know exactly what kind of excitation port I should use. Should I use a waveguide port or a discrete port and why?
3-Actually a u-slot antenna is used for dual band operations but my simulation results (using a waveguide port and RT-Duroid 5880 instead of foam) gives a single wide resonance. I don't know whether this result is reliable or not.