The 20 GHz spacecraft FET solid state transmitter

The engineering development of a solid state transmitter amplifier operating in the 20 GHz frequency band using GaAs field effect transistors (FETs) was detailed. The major efforts include GaAs FET device development, single-ended amplifier stage, balanced amplifier stage, cascaded stage and radial combiner designs, and amplifier integration and test. A multistage GaAs FET amplifier capable of 8.2 W CW output over the 17.9 to 19.1 GHz frequency band was developed. The GaAs FET devices developed represent state of the art FET power device technology. Further device improvements are necessary to increase the bandwidth to 2.5 GHz, improve dc-to-RF efficiency, and increase power capability at the device level. Higher power devices will simplify the amplifier combining scheme, reducing the size and weight of the overall amplifier.