过模慢波结构频率反射特性及谐振腔的影响

利用有限元方法求解:S-参数矩阵，研究了过模慢波结构对圆波导TM01，TM02模的反射特性，分析了在慢波结构末端加入谐振腔后，由于两端口的不对称性而造成的对反射特性影响。结果表明，在TM01的π模频率附近，慢波结构和谐振腔组成的系统对无谐振腔一侧端口入射TM01模的反射增大，而对有谐振腔一侧端口入射TM01模的反射减小。根据计算结果，解释了普通多波切伦柯夫振荡器所用慢波结构周期数较多的原因，说明了在多波切伦柯夫振荡器中引入谐振腔后，不但可以减少所用慢波结构周期数，而且有利于提高微波输出效率。

Reflection dependence on frequency of overmoded slow wave structure and the influence of resonant cavity

The reflection properties of the TM01，TM02 modes of the circular waveguide by overmoded SWS are investigated by solving the S parameters matrix with the method of the finite element method, and the difference between the reflection characteristics of two ports due to the asymmetry because of the introduction of the resonant cavity into one end of the SWS are analyzed. The numerical calculation results show that the reflection to the TM01 mode inputted into the port without resonant cavity increases while the reflection to the TM01 mode inputted into the port with resonant cavity decreases. The reasons that the introduction of the resonant cavity can reduce the needed period number of the SWSs and enhance the output microwave power efficiency are also demonstrated.