A 3D Printed Septum Polarizer Consisting of Circular-to-Rectangular Converting Waveguide

We propose a septum polarizer consisting of circular-to-rectangular converting waveguide. Its structure makes it possible to connect with a circular horn antenna without another circular-to-square converter, so the total axial length of the polarizer is reduced compared to conventional one. In addition, by making the septum's side surface shape serrated, the influence of making the outer wall a tapered circular-to-rectangular conversion structure is compensated, and good axial ratio characteristics are realized. The proposed septum polarizer was fabricated via metal 3D printing. The measurement results demonstrated a reflection of 30 dB, an isolation of 30 dB, an axis ratio of 0.2 dB and a XPD of 40 dB, with a bandwidth of 13% in the K-band for satellite communication systems.