Design and cold test of an S-band waveguide dual circular polarizer

Abstract

Purpose An S-band dual circular polarizer has been designed and tested with low power in the paper, which will be applied in a spherical cavity pulse compressor. It converts the TE 10 mode in rectangular waveguide into two polarization degenerated TE 11 modes in cylindrical waveguide. Methods The general scattering matrix of the dual circular polarizer has been deduced based on the properties of the passive microwave network, which is suitable for the usual 3 dB coupler, as well as the left/right hand circular polarizer. Based on the 3D code software CST, the dual circular polarizer was numerically simulated. Then, two prototypes have been manufactured and tested with the vector network analyzer (VNA). Results The simulation results show that the magnitudes and phase difference of the two TE 11 modes are − 3.0103/− 3.0104 dB and 89.79 degrees, respectively. The cold test results show good agreement with CST simulation. Conclusion The method of analyzing the relationship between the voltage standing wave ratio (VSWR) and the errors of the magnitudes and phase difference of the two TE 11 modes was given, which can be used to qualitatively analyze the properties of the circular polarizer. The S-band waveguide dual circular polarizer can be applied in the pulse compressor, phase shifter or other frequency bands.