Optimization Design of the Input Coupler for W-band Gyroklystron

In this paper, an input coupler of W-band TE01 mode gyroklystron is designed. Structure dimensions of the input coupler are obtained through the theory analysis. Results from 3-D electromagnetic simulation software CST, HFSS and FEKO are applied to its verification and optimization. The effects on the coupling frequency and quality factor from some dimensions, including dimensions of the apertures and the radius of the cylindrical cavity, are also researched. Besides, the mode purity in the cylindrical cavity is calculated. The results show that the TE01 mode is obtained in the cylindrical cavity, with the coupling frequency of 93.55 GHz, external quality factor of 145, and the mode purity of 99%.