阶梯槽交错双栅慢波结构高频特性理论和模拟

摘要

Based on a staggered double-grating slow wave structure with step-shaped grooves, the expressions of the elec-tromagnetic field in it have been obtained and the formulae of the dispersion equation and coupling impedance have been solved by means of field matching method. As an example, a staggered double-grating slow wave structure for W band TWT application was used to calculate the characteristics of dispersion and coupling impedance using the formu-lae and CST-MWS code, and analyze the effect of the step dimension variation on the high frequency characteristics. Results show that the theoretical calculations are in good agreement with the CST-MWS code simulations, and the slow wave structure can improve the dispersion characteristics, enhance interaction bandwidth, while keeping a proper coupling impedance and mechanical intensity, which can to some extent compensate for the deficiency in the staggered double-grating slow wave structure with the rectangular-shaped grooves.%本文基于一种阶梯槽交错双栅周期慢波结构模型，获得了该结构中的电磁场分布公式。通过场匹配方法，求出了该结构的高频色散方程和耦合阻抗表达式。以W波段行波管用的阶梯槽交错双栅为例，利用本文公式和CST-MWS电磁软件比较计算了色散和耦合阻抗特性，分析了阶梯尺寸参数对高频特性(基模色散、+1次空间谐波归一化相速和耦合阻抗)的影响。结果表明，理论和CST-MWS软件模拟有很好的一致性；相对矩形交错双栅，改善了色散特性，拓展了基模带宽，同时具有足够大的耦合阻抗和适合工程应用的机械强度，在一定程度上可以弥补矩形交错双栅周期慢波结构的不足。