Polarization Angle in Frequency Selective Surface simulation at CST MW Studio.

I am using CST Microwave Studio for Frequency Selective Surface (FSS) design. In the unit cell simulation setup i can change only the incidence angle. The solver generates output only for TE and TM polarization.
[Q1]But how could i simulate for polarization angles other than 0 or 90 Degree. (Ex: I want the Tx,Rx response for polarization angle of 60 Degree).
[Q2]During practical measurements antenna is rotated to get different polarizations. Practically only the incidence direction is known. But without knowing the incidence plane, how the the TE and TM polarizations are possible with practical antenna.

Please help me.