Review of TWT developments above 18 GHz

The development of travelling wave tube (TWT) amplifiers to the production stage for Satcom transmissions above 18 GHz is discussed from the point of view of one manufacturer. A 20 GHz TWT was first flown on the ATS-6 satellite, followed by the manufacture of 23 and 32 GHz TWTs for the Intelsat Inter-satellite links. Outputs of up to 75 W at 34 GHz have been attained. A 25 W, 20 GHz TWT with 50 dB gain is under development for the USAF and features a type-M dispenser cathode in an unpotted gun on a BeO helix support structure. The device has yet to undergo detailed thermal and structural analyses to become space-rated. A 50 W, 20 GHz multimode TWT capable of 5, 17 and 50 W saturation levels is being tested and will provide output power optimization for particular propagation loss conditions. The device is intended for MILSTAR applications and will be produced in a monitored production line.