Small Signal Treatment of a 94-GHz Helical Waveguide TWT

This paper estimates with a simplified analytical model the small signal gain of a helically arranged groove-guide traveling-wave tube. It follows closely the transmission line theory approach with the modifications necessary for the very particular device. At 94 GHz and for a 15-kV, 1-A beam, a gain of ~ 1 dB per winding was derived, and realistic gains between 0.6 and 0.8 dB seem to be possible.