Improved design of input and output structures of W-band gyro-TWT

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. (authors)