The design, fabrication and performance of a frequency selective surface (FSS) which is required to operate as broadband sub-reflector of Ka band antenna for satellite communication application is proposed and validated experimentally. In order to obtain this spatial filter which exhibits low insertion losses and insensitivities to the variation of oblique incident angle for TE and TM polarized wave, the mode-matching method is applied to the analysis of the geometrical structure and electrical parameters of FSS unit cell, and the fabrication process of this Ka FSS sub-reflector utilizing sophisticated quartz wafer coating technology is described. Electromagnetic field simulations and measurements results demonstrate that this FSS filter has virtually identical spectral responses in the two polarization planes.