Design of a Broad-band Circular Waveguide TE°21 Mode Generator for Cold Test of Gyro-TWT

In this paper, the design of a broadband circular waveguide TE degrees(21) mode generator for gyro-TWT cold test is presented. The proposed mode generator is constituted by a rectangular waveguide TE10 rectangle to rectangular waveguide TE20 rectangle mode converter, a rectangular waveguide TE20 rectangle to crossing waveguide TE22+ mode converter and the converter from TE22+ to TE degrees(21) mode. The linear gradient structure is adopted in each convert for easy fabricating. Simulation results reveal that the S-21 parameter of the proposed TE degrees(21) mode converter is better than -0.037dB and the S-11 parameter is below -28dB in whole Q-band. Cold test shows that the designed generator realizes high conversion efficiency (>96.6%) in whole Q-band.