Purely Metallic Waveguide-Fed Fabry–Perot Cavity Antenna With a Polarizing Frequency Selective Surface for Compact Solutions in Circular Polarization

A completely metallic Fabry–Perot (FP) cavity antenna is proposed with a polarizing radome on top as a compact alternative solution that could replace advantageously bulky horn antennas for high-power space applications in circular polarization. It consists of a stacked FP resonator, covered by a linear-to-circular polarization converting layer. Experimental results for a $2.5\lambda _{0}$ aperture size in $S$ -band (around 2.5 GHz) show a 1-dB axial-ratio bandwidth of 1.6% with a maximum gain level of 16.7 dB and a reflection coefficient lower than ${- }$ 15 dB over the entire frequency band.