基于波导模式变换的圆波导TE62模式激励器的研究

基于不规则波导模式匹配法以及缓变波导中电磁波模式耦合理论，研究了一种W波段圆波导TE₆₂模式激励器. 该波导模式激励器采用矩形波导TE₁₀模式通过侧壁耦合馈入同轴波导，利用同轴波导的选模特性激励TE₆₁模式；随后利用轴向半径周期微扰的圆波导实现TE₆₁–TE₆₂模式变换. 文中推导了矩形-同轴波导模式匹配理论，系统研究了波导结构缓变参数对模式变换效率的影响，完成了模式变换器的优化仿真设计，数值计算结果表明：中心频率处TE₆₂模式的转换效率为94.5%，纯度为98.16%，效率85%以上带宽达到1 GHz，能够满足回旋管冷测的要求. 关键词： 同轴波导 模式变换 耦合模理论 半径微扰

Study of a W-band TE62 mode generator by the waveguide mode transformation

In this paper, based on the theory of mode-matching and the coupled wave theory, A W-band TE₆₂ mode generator by using waveguide mode transformation is presented. Because of the eigen-mode selection of coaxial waveguide, a TE₁ mode in standard rectangular waveguide is coupled into a coaxial waveguide to excite a TE₆₁ mode by an aperture. A transition follows on it to change the coaxial waveguide into a circular one. Finally, TE₆₁–TE₆₂ mode converter is achieved by using a periodic radius perturbation in circular waveguide. Calculation and analysis of the relationship between the mode conversion efficiency and structure parameters of waveguide also are finished. The validity of this study is confirmed by using electromagnetic simulation software. The conversion efficiency of TE₆₂ mode reaches 94.5% at the center frequency 95 GHz, and the mode purity reaches 98.16% The bandwidth of the efficiency above 85% reaches 1 GHz, which can meet the demand of the high–frequency cold test of gyrotrons.
Keywords： coaxial waveguide mode converter coupled wave theory radius perturbation