A Multilayer Circular Polarizer Based on Bisected Split-Ring Frequency Selective Surfaces

This letter presents a circular polarizer using a multilayer frequency selective surface based on split rings bisected by a metal strip. This geometry provides the advantages of both low cross-polarization level and low sensibility with respect to the incidence angle of the ring-based topology. To validate the proposed design, a four-layer prototype to operate in Ka-band has been designed, fabricated, and tested. Experimental results show that axial ratios lower than 3 dB are obtained for angles of incidence as high as 25 ° over the frequency range of 25.5-36.5 GHz.