在回旋行波放大器的设计中, 输入输出段的性能直接影响到整管输出功率、效率及增益。设计了一种采用渐变过渡段的输入耦合器来减少电子注在前端的截获, 而且略微地提高了耦合特性, 有效带宽达到4.06 GHz。采用二级切比雪夫渐变波导作为输出结构的耦合输出段, 从仿真结果得到, 在整个工作频段内, 该结构中TE01工作模式的反射低于-20 dB, TE01模向杂模TE02和TE03的耦合分别在-20 dB和-30 dB以下。

An improved input coupler with tapered transitional section and output structure adopting cascaded Chebyshev waveguide, working in TE01 mode, has been designed for W band gyro-TWT. By means of theoretic analysis and numerical computation in Matlab, the outer radius, the length of input coupler’s cavity and two contours of the section of coupling output are obtained. According to the optimized results in HFSS, the bandwidth of the improved input coupler which meets the demand of S11 less than -20 dB and S21 greater than -0.1 dB is 4.06 GHz. The cascaded Chebyshev structure has good performance on transmitting TE01 mode and suppressing spurious modes with acceptable length.