Quasi-Optical Orthomode Splitters for Input–Output of a Powerful <tex-math notation='LaTeX'>${W}$ </tex-math> -Band Gyro-TWT

Three different designs of an external microwave system for feeding and extracting power to and from a gyrotron traveling-wave tube (gyro-TWT) through one oversized port are presented and discussed. As it shown, such a microwave system should operate as a splitter which splits two wavebeams with mutually orthogonal polarizations incoming through one port into two spatially separated ports or transmission lines transporting each wavebeam individually. The orthomode splitters presented in this paper were designed to be used with a gyro-TWT producing 350- and 50-kW maximum pulsed and average powers, respectively, with a 3-dB bandwidth of 10 GHz at the center frequency of 95 GHz. Such a high-power level and wide bandwidth at short millimeter waves make quasi-optical components to be the most appropriate solutions in contrast to low-mode standard waveguide circuits.