交錯耦合微帶線濾波器的調整與診斷

Abstract

本論文主要在研究如何萃取交錯耦合濾波器之等效電路參數，進而調整濾波器使其達到預先設定之響應。一般而言，交錯耦合濾波器之等效電路參數可由一個耦合矩陣來表示，文中將對耦合矩陣的萃取與合成方法有詳盡的討論。同時文中也提出了系統化的設計與調整濾波器的步驟。而這樣的方法與步驟可有效地用來分析微帶線濾波器中的交錯耦合效應、共振腔頻率校正等問題。其中，對於具有源級與負載相耦合(source-load coupling)的四角互耦(quadruplet)結構有詳盡的討論。此外，文中也提出了如何快速設計具高止帶頻率選擇性的串接三角互耦(cascade trisection)濾波器。除了在單模濾波器的應用外，文中也深入探討了如何混用單模與雙模共振腔來實踐具廣義查比雪夫響應之似盒狀(box-like)耦合濾波器。另外，文中也提出了一種新的參數萃取法，此法可以從濾波器的響應同時萃取出耦合矩陣與無外加負載之品質因子(unloaded quality factor)。此種參數萃取法可以實際用於有損濾波器的分析與調整。

This Dissertation presents how to extract the equivalent circuit parameters of cross-coupled filters. From the extracted parameters, one can decide how to tune a filter to achieve the prescribed response systematically. In most cases, the cross-coupled filters can be described by a coupling matrix. Thus, how to extract and synthesize a coupling matrix with a given response would be discussed in detail. Besides, a systematical procedure for filter design and tuning is given. With these developed methods, one can effectively analyze the effect of cross couplings and asynchronous resonant frequencies of resonators in microstrip filters. As an example, the quadruplet filters with source-load coupling are discussed in detail. And a cascade trisection filter with high selectivity in upper stopband is proposed. In addition to the design of single-mode resonator filters, we investigate how to utilize the dual-mode resonator with single-mode resonators to realize box-like filters with generalized Chebyshev response. To extract a coupling matrix and an unloaded quality factor of a filter from a simulated/measured response simultaneously, a novel parameter extraction method is proposed. This parameter extraction method can be used to analyze and tune lossy filters.