X波段过模弯曲圆波导TM01-HE11模式变换器研究

在波束波导和反射面天线的馈源应用中, 为了产生低副瓣且方向图等化的高斯波束, 需要将高功率微波转换为准高斯模HE₁₁模辐射. 本文利用弯曲圆波导可同时从TM₀₁模产生TE₁₁模和TM₁₁模的原理, 提出了采用双弯曲过模圆波导结构直接将TM₀₁转换为HE₁₁的模式变换器, 避免了常规微波领域中首先将TM₀₁转换为TE₁₁再用波纹式或半径渐变式TE₁₁-HE₁₁转换器转换为准高斯波束功率容量不足或尺寸过长的不足. 基于模式耦合理论和Taguchi优化算法对模式变换器的弯曲半径、相移直端长度及引入位置进行了优化, 使输出的TE₁₁和TM₁₁成一定比率, 以组成HE₁₁模式, 并对设计的模式变换器进行了全电磁波仿真分析, 结果表明输出波束的标量高斯含量在9.05–9.8 GHz范围内均高于99%, 理论功率容量可达4.5 GW. 关键词： 高功率微波 模式耦合理论 Taguchi优化算法 模式变换器

Investigation of an X-band over-moded bent circular waveguide TM01-HE11 mode converter

In the application of low loss beam waveguides and high performance reflector antennas, high power microwave should be converted to quasi-Gaussian HE₁₁ mode, to decrease side lobe level and increase feed coefficient. Based on the fact that TM₀₁ mode converts to TE₁₁ and TM₁₁ mode at the same time in bent overmode circular waveguide, a TM₀₁ to HE₁₁ mode converter was proposed in this paper, which can convert TM₀₁ mode to HE₁₁ mode directly using a bent circular waveguide, the converter has higher power compacity than corrugated TE₁₁-HE₁₁ mode converter and more compact than TE₁₁-TM₀₁ mode converter added with smooth wall TE₁₁-HE₁₁ mode converter. The geometric parameters of the convertor were analyzed and optimized by using coupled mode theory and Taguchi method, to output the target modes content, 80% TE₁₁ and 20% TM₁₁ modes, which are primarily composed of HE₁₁ mode. The optimized converter was analyzed using full electro-magnetic simulation method, the scalar Gauss ratio of the output beam is higher than 99% from 9.05 GHz to 9.8 GHz, the power capacity is as high as 4.5 GW.