A high-efficiency 59- to 64-GHz TWT for intersatellite communications

The design of a 75-W, 59-64 GHz TWT (traveling wave tube) with a predicted overall efficiency in excess of 40% is described. This intersatellite communications TWT, designated the Hughes Aircraft Company Model 961HA, uses a coupled-cavity slow-wave structure with a two-step velocity taper and an isotropic graphite multistage depressed collector (MDC). Because of the RF efficiency of this TWT is less than 8%, an MDC design providing a very high collector efficiency was necessary to achieve the overall efficiency goal of 40%. Measurements indicated a very high MDC efficiency of 93.9%, very close to the computed value. >