Theoretical Investigation into an Ultra-Wideband Helix Traveling-Wave Tube

In this paper, a new ultra-wideband (18–40 GHz) helix traveling-wave tube (TWT) is proposed. The transmission characteristics and high frequency characteristics are simulated by using CST and HFSS, respectively. It is shown that the voltage standing wave ratio (VSWR) of the input/output couplers is below 1.5 in the operating band. In order to improve the whole performances of the proposed helix TWT, a helix pitch step method is employed to optimize the slow-wave structure (SWS) by using a 2.5-D large signal code to simulate nonlinear beam-wave interaction. When the operating voltage and beam current are 10 kV and 100 mA, respectively, and the length of the helix SWS is 150 mm, it is observed from the simulation results that the saturated output power and saturated gain are over 80 W and 40 dB. This proposed device is very useful for application to electronic warfare.