A Wideband Filtering Linear-to-Circular Polarization Converter for Ka-Band Satellite Communication

In this paper, a wideband filtering linear-to-circular polarization converter (LCPC) for Ka-band satellite communication is presented. The proposed converter element consists of two-layer PCBs. To achieve the filtering function, the upper board is a frequency selective surface (FSS) and the lower is a LCPC. Both of two structures have wideband characteristics. By co-design of both two boards, the proposed filtering converter performs a wide 3-dB axial ratio (AR) bandwidth and high frequency selectivity at the right side of the passband. The final prototype working at the center frequency of 32.5 GHz is fabricated and measured. The measured results have a good agreement with the simulated ones. The relative 3-dB bandwidths of the passband and AR are 12.3% and 15.4% respectively, where the overlapping bandwidth is 12.3%. Besides, a transmission zero at 36.5 GHz to enhance filtering performance is achieved. This design is suitable for the satellite communication.