Hello
Thank you very much for your reply.
However I don't know how to determine which modes can be present inside my cavity due to the antenna radiation.
Do I have to:
1/ assume the cavity modes independant of the antenna (and its radiation) placed inside. The modes only depend on the cavity configuration and the frequency of interest. I could then compute the modes, at the frequency of interest, by simulating the cavity with a "testing" antenna (small loop, small dipole, a punctual source...). Then I could determine the orientation of the E field vector inside. And hence the kind of symetry planes to apply afterwards with the actual antenna inside the cavity.
2/or if I compute the E-field vectors at the vicinity of the antenna when it is in free space, I can deduce the kind of symetry planes to apply afterwards with the actual antenna inside the cavity?
I guess the reality is more complex...
Thank you very much for your reply