An Improved Serpentine Waveguide Slow Wave Structure for Balanced Gain in Band

An optimized serpentine waveguide slow wave structure (SWS) for gain equalization is proposed in this article. The SWS is divided into three stages, adjusting the dimensions of waveguide units of every part to change the phase velocity and coupling impedance. By suppressing gain at low frequencies while enhancing that of high frequencies, the TWT based on this SWS can ultimately achieve balanced gain throughout the entire frequency band. Meanwhile, the three-stage SWS can reduce the likelihood of self-oscillations. According to simulation results by CST Studio Suite, the proposed TWT demonstrates a gain exceeding 50 dB within the frequency band. Additionally, it exhibits a maximum gain fluctuation of no more than 3.5 dB within the bandwidth, which is reduced by 20.5 % compared to conventional periodic serpentine waveguide TWT. These results indicate that the SWS provided can greatly enhance the device's balance gain performance, offering valuable references for designing TWTs.