Input coupler design for W band gyrotron TWT

In this paper, an input coupler for W band gyrotron TWT (Traveling Wave Tube) has been designed. This input coupler has the ability of efficiently converts a TE10 rectangular waveguide mode into a TE01 cylindrical waveguide mode. The measured results agree well with the simulated results. With the measured -2dB bandwidth of more than 4GHz, the input coupler can be well used in the experiment of W band gyrotron traveling wave amplifier.