A 100 watt TWT amplifier for the space shuttle

A high efficiency 100 watt traveling-wave tube amplifier for space communication at C-band, 5.9- 6.4 GHz, with integrated power supply and heat pipe cooling is described. The tube incorporates a helix slow wave structure with a velocity resynchronization taper and three-stage doubly-depressed collector for efficiency enhancement. The tube generates RF power at an overall efficiency of 50%, while the power conditioner maintains greater than 80% efficiency over line, load and temperature variations. The TWTA therefore delivers RF power at over 40% efficiency from an unregulated DC power line. High efficiency, as an integrated TWTA, is achieved without sacrifice of communication system type parameters such as AM/PM conversion, transfer curve linearity, and intermodulation distortion.