What are your thoughts about the impact of a CP antenna when having it illuminating on to a symmetric frequency selective surface? Will the antenna's CP quality be degraded by the FSS or not? Thanks very much.
What do you mean by FSS? (The term is rather ambiguous, in my experience.)
If the FSS is acting like a radome, then proper symmetry should ensure that it affects both linear components of the CP wave equally, so the output should still be CP.