A High-Power and High-Efficiency Bend Overmode Coaxial Waveguide

A bend overmode coaxial waveguide with advantages of high-efficiency and high-power handling capacity is investigated. The principle of the proposed waveguide is as follows: the TEM mode in the coaxial waveguide is converted to TE11 modes of two 180° sector waveguides, and then the sector waveguide bends with a demanded turning angle, afterward the TE11 modes in the two sector waveguides are merged into the TEM mode of the coaxial waveguide. A C-band waveguide prototype with a center frequency of 4.0 GHz and a turning angle of 45 is designed and fabricated. The experiment results show that: the transmission loss of the fundamental mode at the center frequency is 0.2 dB and the VSRW is 1.1. When the frequency ranges from 3.8 to 4.2 GHz, the transmission loss of the fundamental mode is less than 0.4 dB and the VSWR is less than 1.5. The field distributions of this waveguide are analyzed through simulation, which prove its advantage of high-power handling capacity.