A Ka-Band TE Mode Converter

A Ka-band rectangular TEio mode (TE10 square) to circular TEN mode (TE01o) converter with high efficiency, high mode purity, compactness and easy fabrication is proposed. It consists of a TE10 square- TE20 square, mode-converting section and a TE20 square-TE10 square, mode-converting section. This improved sidewall-type TE10 square-mode converter with built-in pins based on the stepped waveguide technique is easier to fabricate and performs well. The optimized simulation results show that the converter achieves a mode purity greater than 98% with a conversion efficiency of nearly 96% within the frequency band of 32.28 GHz to 37.54 GHz and that it is less than 6 wavelengths (to the center frequency 34.5 GHz) in length. A back-to-back measurement of such converters and a near-field test of the output of the converter indicate a very good agreement with the corresponding simulation results.