波导耦合波理论反演问题的迭代求解方法研究

Waveguide coupled-wave theory is mainly used to describe the overmoded waveguide components, and the inverse problem is a functional optimization problem, the optimization objective of which is to maximize the conversion efficiency, and the optimization function is the structure function. Because of the complexity of this problem, conventional methods make many assumptions based on the properties of the components to obtain approximate solutions, which usually are not the best solutions, and this restricts the applicability of the conventional methods. An iteration method is proposed to solve the inverse problem directly in recent years, and the successful design of many kinds of the overmoded waveguide components proves the effectiveness of the iteration method, and compared with the conventional methods, the components designed by iteration method have better electrical properties and structural performance. However, the iteration method is based on the coupled wave equations so far, and the cut-off section problem restricts the applied range, otherwise, the multi-frequency design method is preliminary studied, and the superior performances need to dig-out. According to this situation, a steepest decent iterative procedure based on generalized transmission line equations will be established in this project to solve the inverse problem, and the multi-frequency design method will be further studied to master the design method of large bandwidth multiband or mode filter components, and finally an improved design system of the overmoded waveguide components will be established.

波导耦合波理论主要用于描述过模波导器件，其反演问题为泛函最优化问题，优化目标为转换效率，优化变量为结构函数。由于问题的复杂性，传统设计方法往往根据器件特性做假设以求得近似解，器件性能并非最优，且方法不具有普适性。最近几年提出了反演问题的迭代解法，设计实例表明迭代法对多种不同类型的器件都能有效设计，而且电性能和结构性能相比于传统设计方法更优越。然而，目前迭代法仍然以耦合波方程组作为分析基础，截止截面问题限制了迭代法的应用范围，另外，以迭代法为基础的多频设计方法仅作了初步研究，其优异性能未能充分挖掘。针对这一研究现状，本项目拟以广义传输线方程组作为分析基础，建立耦合波理论反演问题的最速下降迭代求解流程，并深入研究多频设计方法，掌握大带宽、多波段、模式滤波等频响特性实现方法，最终有效解决波导耦合波理论反演问题，并建立一套完善的过模波导器件设计体系。

非均匀过模波导器件广泛应用于高功率微波系统之中。过模波导采用波导耦合波理论进行描述，设计问题为泛函最优化问题，优化目标为转换效率，优化变量为结构函数。由于问题的复杂性，传统设计方法往往根据器件特性做假设以求得近似解，器件性能并非最优，且方法不具有普适性。最近几年提出了反演问题的迭代解法，设计实例表明迭代法对多种不同类型的器件都能有效设计，而且电性能和结构性能相比于传统设计方法更优越。然而，迭代法仍然以耦合波方程组作为分析基础，截止截面问题限制了迭代法的应用范围，另外，以迭代法为基础的多频设计方法仅作了初步研究，其优异性能未能充分挖掘。针对这一研究现状，本项目深入分析了截止截面问题产生的根本原因，提出了以广义传输线方程组作为分析基础，并建立了耦合波理论反演问题的最速下降迭代求解流程，同时，并深入研究多频设计方法，掌握大带宽、多波段频响特性器件的实现方法。理论设计了椭圆TE01-TE11模式变换器、紧凑型TM01过渡器和双频TM01-TE11模式变换器，仿真软件仿真结果表明所提出的方法能够较好的应用于各类模式变换器设计之中，验证了方法的正确性。