A new family of MM wave TWTs for telecom and ECM applications

Twenty years after the first breadboard activities, the development of MM wave TWTs operating from 18 to 60 GHz is booming again, stimulated by the growth of multimedia satcom services and the high data rate upgrade of military telecommunication networks. Recent design activities at Thomson Tubes Electroniques (TTE) have borne in particular on the qualification of a 40 W Ka band microTWT and on the development of a 120 W EHF band TWT: (a) the 40 W Ka band model features small size (7 inches), broad instantaneous bandwidth (25.5 to 31.5 GHz) and high efficiency (35%). A small series of tubes has been manufactured in 1999, from which one unit has been successfully qualified. A life test is running on two TWTs: at 1005/spl deg/Cb cathode temperature, the RF output power decrease is roughly 1.5% after 6500 operating hours. (b) The 120 W EHF dual stage collector TWT is currently in development. A first breadboard has delivered the expected power level (120 to 130 W from 43.5 to 45.5 GHz) with the same beam parameters as the 80 W model currently in production. After minor design adjustments in gun and collector areas, two prototypes have been built and will soon be tested. Design activities have started on upgrading several other MM wave products (higher performance or lower cost). These include a 160 W Ka band dual stage collector model and an 80 W K+Ka band TWT.