阶梯槽交错双栅慢波结构高频特性理论和模拟

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.

Theory and simulations of high frequency characteristics for a staggered double-grating slow-wave structure with step-shaped grooves

Based on a staggered double-grating slow wave structure with step-shaped grooves, the expressions of the electromagnetic 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 formulae 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.