过模波导器件的迭代设计方法

Iterative method for multimode waveguide design

从模式保留和转换的角度,过模波导器件可分为模式转换器、模式保留器和模式综合器.传统方法只解决其中一种器件的设计或者对器件的某个指标进行改进.本文在深入分析耦合波理论之后,提出了过模波导器件的迭代设计方法,从原理上解决了过模波导器件的设计问题.该方法能够统一设计三类过模波导器件,通过添加不同的结构控制方法,可得到转换效率更高、带宽更宽、结构更紧凑、满足不同工程需求的器件,而且还能有效设计一些新型器件.给出了两个设计实例:双频TM01—TE11模式变换器和光壁馈源喇叭.双频TM01—TE11模式变换器的两个工作频点为8.75GHz和10.3GHz,波导半径为16mm,在两个频点转换效率为99%以上.光壁馈源喇叭实现TE11模式向高斯束的转换.CST仿真结果验证了这两个器件设计的正确性和有效性.

Coupled mode theory is an effective tool for analysis and synthesis of overmoded waveguides, but the inverse problem has not been solved yet. This paper completed the iterative procedure to solve the inverse problem. The new method can design automatically and fast various mode converters, mode transducers and horn antennas with special radial pattern. Compared with conventional methods, the structure design using the new method has more advantages in electromagnetic and structural properties. Two design examples are given： dual band TM01-TEH mode converter and smooth-wall feed horn antenna. The two working frequencies of the dual band TM01-TEll mode converter are 8.75 GHz and 10.3 GHz, and the radius is 16 ram. The converter efficiencies exceed 99% at the two working frequencies. The smooth-wall feed horn antenna converts the TEll mode to Gaussian beam effectively. Simulation results agree well with the theoretical predictions.