Design and measurement of a broadband sidewall coupler for a W-band gyro-TWA

Zhang, Liang and He, Wenlong and Donaldson, Craig R. and Garner, Jason R. and McElhinney, Paul and Cross, Adrian W. (2015) Design and measurement of a broadband sidewall coupler for a W-band gyro-TWA. IEEE Transactions on Microwave Theory and Techniques, 63 (10). pp. 3183-3190. ISSN 0018-9480 (https://doi.org/10.1109/TMTT.2015.2464302)

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Abstract

The input coupler is an important component for a microwave amplifier. In this paper, a sidewall single-hole input coupler for a W-band gyrotron traveling-wave amplifier that operates at the frequency range of 90–100 GHz was designed and measured. Instead of using a cutoff waveguide, a broadband Braggtype reflector with a small spread in phase was optimized for use as part of the input coupler. The minimum radius of the reflector was two times the size of a cutoff waveguide, which reduced the possibility for some of the beam electrons being collected in this section and lost to the amplifier interaction region.