本論文主要係使用對稱及非對稱並聯段枝人工傳輸線實現一系列微波主、被動電路，如分枝耦合器、功率分配器、電壓調控相位移器及電子式波束掃描相位陣列天線。在本論文中，傳統微帶線可被等效成一π型對稱人工傳輸線，其結構係由一段串聯的高阻抗微帶線及兩側低阻抗並聯段枝所構成。再將此低阻抗傳輸線等效成樹枝狀及準集總電容結構，搭配彎折技術則可將該人工傳輸線作更彈性之電路佈局，進一步達成電路縮小之目的。另一方面，傳統的微帶線亦可被等效成T型非對稱人工傳輸線，並利用此種人工傳輸線研製分枝耦合器，以改善耦合器微小化後之反射損耗頻寬縮小之問題。
本論文中，利用π型對稱並聯段枝人工傳輸線為基礎，使用樹枝狀及準集總電容所研製之3-dB分枝耦合器，其電路面積可縮小為傳統電路之8 %及13.9 %。此外，6-dB分枝耦合器及功率分配器之電路面積縮小為傳統電路8.2 %及14.7 %。另一方面，利用非對稱人工傳輸線則可研製電路面積縮小為傳統電路16 %, 16.9 %及22.3 %之三型3-dB分枝耦合器。實驗結果驗證，使用非對稱人工傳輸線除可有效縮小電路面積，亦可提供傳統分枝耦合器相近之反射損耗頻寬。
最後，本論文將第二章分枝耦合器之設計概念應用於研製阻抗轉換分枝耦合器，據以實現電壓調控反射式相位移器。再將第二章所研製之功率分配器輸出端接上兩相位移器，並結合偶極天線，則可整合成電子式波束掃描相位陣列天線。

In this thesis, the shunt-stub-based artificial line (SSB ATL) and asymmetrical shunt-stub-based artificial transmission lines (ASSB ATL) have been applied to develop compact planar branch-line couplers and Wilkinson power divider. Then they are employed to design a refection-type phase shifter and a two-element beam-scanning phase array antenna. A conventional microstrip line can be equivalent to an SSB ATL realized by a series high-impedance microstrip line with bilateral low-impedance shunt stubs. The low-impedance stubs can be further replaced by branch-type and distributed-capacitor structures for the circuit size miniaturization. On the other hand, a conventional microstrip line also can be equivalent to an ASSB ATL and then employed to implement the bandwidth-enhanced branch-line coupler.
Compact 3-dB branch-line couplers with branch-type and distributed capacitor structures respectively occupy about 8% and 13.9% circuit size of the conventional coupler at 0.9 GHz. The developed power divider using π-equivalent SSB ATLs occupies 14.7% circuit size as compared with the conventional case. In addition, the ASSB ATLs are used to improve the return loss bandwidth of the compact couplers. The three types of the developed couplers have 16 %, 16.9 %, and 22.3 % circuit sizes as compared with conventional structures.
Furthermore, the SSB ATLs can be adopted to implement an impedance-transforming branch-line coupler, and then applied to design an electronic reflection-type phase shifter. As integrating with the developed compact Wilkinson power divider, one can achieve a two-element beam-forming network. Then connecting two dipole antennas with the output ports of the beam forming network, the electronic beam-scanning phased array antenna can be successfully developed.

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