A Septum Polarizer with Integrated Square to Circular Tapered Waveguide Transition

A compact septum polarizer has been designed, manufactured and tested with an integrated square to circular tapered waveguide transition yielding two linearly polarized rectangular waveguide ports and one circularly polarized circular waveguide port. The measured S-parameters and axial ratio (AR) are compared with simulated values from CST Microwave Studio. From 18.5–21.5GHz, the AR is less than 0.6dB, insertion loss is less than 0.25dB, and return loss is greater than 25dB.