Design of helix slow-wave structure for ultra-wideband traveling-wave tube with low gain fluctuation

This paper describes a fan-shaped metal-loaded helix slow-wave structure (SWS) to develop ultra-wideband traveling-wave tube with low gain fluctuation. The electromagnetic characteristics and beam-wave interaction of this structure are calculated. The simulation results show that the helix TWT gain is more than 42dB and the signal gain fluctuation of the TWT is less than 2.5dB in a frequency range from 15 to 35 GHz. In addition, the maximum output power can reach 199 W at 21 GHz, corresponding to the maximum electronic efficiency is 16.6%.