Dual-band bi-phase waveguide polarizer for a novel feeder network without orthomode transducer

Waveguide polarizers are essential devices in communication systems used as horn feeders for achieving circular polarization. In this paper a new bi-phase waveguide polarizer for working in two different frequency bands is proposed. Furthermore, the presented polarizer is the critical component of a completely new feeder network proposed herein, which does not require Orthomode Transducer. The design and full-wave optimization of the novel structure realized in rectangular waveguide is presented. The full-wave analysis is carried out with efficient Computer Aided Design (CAD) software based on the Mode-Matching technique. A high performance in polarization purity is obtained in comparison with existing dual-band waveguide polarizers. The optimized design presents a return loss better than 27 dB for both polarizations (vertical and horizontal) in both bands and a phase difference of 90°±0.7° (equivalent to an axial ratio better than 0.12 dB or a maximum cross-polar level of -45 dB).