Characterization of W-band Serpentine Waveguide TWT Circuits

We present experimental characterization of W-band serpentine waveguide TWT circuits fabricated by CNC micro-endmill machining. Cold test measurements of S-parameters demonstrate excellent agreement with simulation and precise fabrication repeatability between multiple circuits. The circuit wavelength dispersion was measured in both $W$ - and D-band waveguide bands, covering an octave in frequency, showing agreement with simulation from 85–170 GHz. We discuss details of the fabricated circuits and cold test results.