K-Band Traveling-Wave Tube Amplifier

A new space-qualified, high-power, high-efficiency, K-band traveling-wave tube amplifier (TWTA), shown in the figure, will provide high-rate, high-capacity, direct-to-Earth communications for science data and video gathered by the Lunar Reconnaissance Orbiter (LRO) during its mission. The TWTA is designed for 20 years of operational life, well in excess of the expected 7 years of mission life. It is a vacuum electronics device that is used to amplify microwave communications signals. TWTs are needed for high-frequency and high-power applications, such as communications from the Moon, because they have significantly higher power capability and efficiency than solid-state devices. Amplification in a TWT is by a factor of about 100,000. The RF power and data rate values for the LRO TWTA, when compared with other space based K-band transmitters, are an order of magnitude higher and represent a new state of the art.