包含源与负载耦合的滤波器诊断与调试方法

柯西法目前仅适用于诊断不包含源与负载耦合的带通滤波器。为解决这一问题,提出了一种能够诊断包含源与负载耦合的带通、带阻谐振腔滤波器的方法。利用遗传算法优化获得源与负载耦合系数并移除滤波器输入/输出端口处传输线引起的S参数的相位加载效应;使用柯西法一步确定仿真S参数对应的特征多项式;从获得的源与负载耦合系数和特征多项式中,利用已有的技术诊断出N+2阶耦合矩阵。此方法可用于指导滤波器的调试,通过对比理想的耦合矩阵与提取的耦合矩阵之间的差异,可确定滤波器问题出自何处以及调试的方向,从而加快滤波器的设计与实现。

Method for diagnosis and tuning of cross-coupled resonator bandstop and bandpass filters with source-load coupling

Cauchy method can only diagnose the bandpass filters without source-load coupling. To solve this problem, a method is proposed for diagnosing cross-coupled resonator bandstop and bandpass filters with source-load coupling. Firstly, an optimization method based on the genetic algorithm (GA) is proposed to determine source-load coupling coefficient, and to remove the phase-shift effects on the simulated S-parameters, which are caused by the transmission lines at the input/output ports of a filter. Secondly, the characteristic polynomials of the S-parameters can be solved in one step using the Cauchy method. Finally, the N+2 coupling matrix of a filter can be extracted from the characteristic polynomials and source-load coupling coefficient using well established techniques. The proposed method can reveal what is wrong with the filter and its tuning direction by comparing the difference between the ideal and the extracted coupling matrix. Therefore, the proposed method can guide the process of the filter tuning which can speed up the design and realization of a cross-coupled resonator bandstop and bandpass filter.