Ka波段行波管带内谐振尖峰问题的仿真与优化

Simulation and Optimization of Resonant Peak in Ka-Band Space TWTs

针对Ka波段空间行波管进一步扩展的工作频带需求,在工作带宽内出现谐振峰振荡的现象,通过对行波管输出系统中同轴波导转换结构的传输线理论分析和CST软件仿真,确定了工作带宽高端出现的驻波比的谐振尖峰是由此结构激励高次模TE_(11)引起的,优化了结构参数,将带内尖峰移除工作频带外,避免了驻波、增益平坦度以及群时延等关键频域指标影响宽带信号失真的问题。

For further expansion of the frequency band of Ka-band space traveling wave tube(TWT),resonant peak occurs frequently in working bandwidth.Through transmission line theoretical analysis and CST software simulation of coaxial waveguide conversion structure in TWT output system,it is concluded that the resonant peak of standing wave ratio at high-end of the working bandwidth is caused by the struc-ture exciting higher-order mode TE11.The structure parameters are optimized and the resonant peak is moved out of the operating frequency band,which avoids the wideband signal distortion resulted by key frequency domain indicators such as standing wave,gain flatness and group delay.