現今的濾波器合成理論，主要可以分為兩大類，其一是先合成出集總電路原型再由微帶線電路元件實現，此類流程雖可設計具額外傳輸零點之電路，因過程中皆假設倒轉器為常數故僅適用於窄頻設計，近年來雖有文獻於合成時考慮隨頻率變化之倒轉器，如以純電容、電感或兩者共同組成之模型，設計具寬頻響應或於通帶外能引入更多零點之集總電路原型，但由於微帶線串聯傳輸線段無法以集總元件模型化，故這些仍不適用於設計寬頻微帶線濾波器，第二類合成流程則是針對微帶線電路特性，以嚴謹的網路理論等效合成濾波器，故電路中的串聯傳輸線段可以是非冗餘性的，但僅適用於設計全極點響應濾波器。為了有效使用到微帶線串聯傳輸線段，本論文針對四種不同電路架構進行討論，前二種皆以串聯傳輸線段作為倒轉器，以開路殘段或短路殘段作為諧振器，設計平行耦合線濾波器，並以此架構為基礎等效合成出具額外傳輸零點之寬頻交錯耦合濾波器，後二種再考慮串聯傳輸線段作為諧振器，以並聯之開路殘段作為倒轉器，設計同樣具額外傳輸零點之寬頻濾波器，再以並聯之短路殘段作為倒轉器設計具微小化特色之濾波器。論文中的設計流程皆是先推導電路之特徵函數，再以數學演算法計算出符合規格之近似函數，以此方式不但能由特徵函數預測出電路之頻率響應，有效掌握到每一個元件之特性，且設計之結果皆能準確符合濾波器規格，並以實作範例驗證論文之正確與實用性。

Although the designs of all-pole filters had been well established, there is still no complete synthesis procedure for broadband microstrip bandpass filters with transmission zeros at the stopband. In order to synthesis the filters with this characteristics, four difference coupling structures of filters have been studied in this research. The series transmission-line sections in these filters are non-redundant. They are uses as the inverters in first type of circuits to synthesis symmetric coupled-line filters with all-pole response. Based on this, second type of circuits are broadband cross-coupled bandpass filter with transmission zeros. Different from the above two circuits, the third type of circuits uses series transmission-line sections as resonators and shunt open-circuited stubs as inverters, which could also introduce transmission zeros. The last circuits uses transmission-line sections as resonators and shunt short-circuited stubs as inverter to design compact size filters. All the circuit responses meet the filter specifications because the rigorous synthesis procedures. The filter design is realized and successfully verified by experiments.

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