Design study of a 372 GHz higher order mode input coupler

Jason R. Garner, Liang Zhang, Craig R. Donaldson, Adrian W. Cross, Wenlong He

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20 Citations (Scopus)
168 Downloads (Pure)


The design of a higher order mode  (HOM) input coupler for a low-THz gyrotron travelling wave amplifier (gyro-TWA) is presented. A two-branch waveguide coupler based on the even distribution of incident power is designed to couple the rectangular TE10 mode to the circular TE61 mode. The optimised tapered waveguide input coupler achieved an operating frequency range of 359 – 385 GHz, equating to a bandwidth of 7%. A prototype waveguide coupler scaled to W-band (75GHz to 110GHz) was manufactured. Vector Network Analyser (VNA) measured return loss of the HOM coupler is shown to be < 10dB at 90 – 96 GHz. A transmission and phase measurement is presented to analyse TE61 mode conversion in the coupler.
Original languageEnglish
Pages (from-to)3284-3290
Number of pages7
JournalIEEE Transactions on Electron Devices
Issue number8
Publication statusPublished - 31 Aug 2016


  • Gyro-TWA
  • mode coupling
  • waveguide coupler
  • THz input coupler


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