A low reflection folded waveguide slow wave structure for millimeter wave traveling wave tube

A modified folded waveguide (FWG) with low reflection is proposed as the slow wave structure (SWS) to design the high power millimeter wave travelling wave tube (TWT). This low reflection folded waveguide (LRFWG) SWS possesses larger interaction impedance and lower reflection parameter than the normal FWG SWS over the whole frequency band. The beam-wave interaction simulation results indicate that the TWT based on LRFWG SWS can generate the maximum output power of 278.5W at 94GHz, corresponding to a gain of 37.45dB and an interaction efficiency of 7.67%.