A Broadband Square Waveguide Septum Polarizer With Notched Septum

A broadband square waveguide septum polarizer with a notched septum is proposed. This method effectively suppresses the parasitic resonance induced by the first higher order mode. A K-band square waveguide septum polarizer featuring a notched septum is designed, fabricated, and measured. The measurement results demonstrate a relative bandwidth of 40%, an insertion loss of less than 0.27 dB, a return loss of more than 22.3 dB, an isolation between two input ports of over 16.9 dB, and an axial ratio of less than 1.3 dB. The proposed waveguide circular polarizer is distinguished for its broad bandwidth and compact size, which present an alternative solution for the design of microwave circular polarized array antenna feeds.