Design and Performance of a High-Efficiency 120-W Q-Band Space Helix TWT.

$Q$ -band traveling-wave tubes (TWTs) with high efficiency and high power will be needed for high-data rate broadband communications in next-generation satellite communication systems. According to the key technical problems and difficulties in the development of $Q$ -band helix TWTs, this article presents a design strategy for high-efficiency and high-power $Q$ -band TWTs. A $Q$ -band helix TWT was successfully manufactured on the basis of this strategy, and the test results indicate that the $Q$ -band helix TWT can operate at up to 120-W continuous-wave output power and with 49.9% minimum overall efficiency over 41.5–45.5 GHz. The group delay and the saturated gain fluctuation of the $Q$ -band TWT over the operating band are only 0.268 nspp and 2.19 dBpp, respectively. The present design strategy is also expected to be applicable to other highly efficient space TWTs, such as $V$ -band space TWTs. [ABSTRACT FROM AUTHOR]