Electronic efficiency and nonlinearity of Ka-band broadband traveling wave tube

The space traveling wave tube (TWT) is a vital device for satellite signal amplification, which determines the lifespan, reliability, and stability of a satellite. Space TWTs require high efficiency and linearity, and bandwidth expansion is a development prospect for TWTs. Optimizing linearity and improving electronic efficiency are crucial for broadband TWTs. This paper reports a study on the influence of the cold parameters of a Ka-band broadband TWTs on the nonlinear phase shift and electronic efficiency. The normalized phase velocity, coupling impedance, and attenuation constant of each frequency were varied to conduct the investigations. The results showed that when the dispersion and coupling curves flatten, the nonlinear phase shift between the high and low frequencies decreases, and the electronic efficiency only decreases slightly. Finally, the slow-wave structure of the T-shaped vane was used to optimize the electronic efficiency and linearity by adjusting the pitch. The electronic efficiency of the 18–24 GHz broadband TWT was greater than 18%, the nonlinear phase shift was less than 60°, and the nonlinear phase shift difference between the high and low frequencies was -12°.