High Performance Circular TE01, Mode Converter

Summary form only given. The development and experimental test of a Ka-band TE₀₁ mode converter are presented. A wave in TE₁₀ rectangular waveguide mode is efficiently converted into the TE₀₁ circular waveguide mode. This converter is composed of a power-dividing section and a mode-converting section. The field pattern and the working principle of each section are analyzed and discussed. A prototype has been built and tested. Back-to-back transmission measurements show excellent agreement with computer simulations. The measured optimum transmissions are 97% with 1-dB bandwidth of 5.8 GHz and 3-dB bandwidth of 7 GHz. High mode purity is predicted in theory and demonstrated in experiment. The field pattern of the circular TE₀₁ mode is directly displayed on a temperature sensitive liquid crystal sheet, where the electric field strength can be discerned from the color spectrum. In addition to three just mentioned advantages, high converting efficiency, high mode purity, and broad bandwidth, this converter also features easy constructions and compact size