微帶線高指向性耦合結構之研究與其應用

Abstract

本論文主要在研究高指向性微帶結構及其應用。在論文的第一部份，我們提出彎折式耦合線結構，其可有效地對偶模波速進行加速，在適當設計下，可使奇偶模波速相等，而使耦合器具有高指向性的效能。我們先設計出一個在極窄頻範圍內可達成極高指向性的耦合器，再經由一些變化，可將其改變成一個在大頻寬範圍內皆具有高指向性的耦合器。我們也將此結構應用在半波長帶通濾波器上，並且成功地抑制了第一次諧振通帶。此結構的設計與合成過程在論文中有完整詳細的說明。在論文的第二部份，提出了一種設計架構，能有效縮小微帶平行弱耦合器的面積，並保有高指向性的效能。

This dissertation presents the research and applications of microstrip coupler with high directivity. In the first part, we proposed a meandered parallel-coupled line. It can speed up the even-mode phase velocity and make the modal phase velocities to be equal in microstrip structure. Therefore, we can get a good directivity in microstrip parallel-coupled coupler. With proper design, we can get an ultra high directivity in a narrow band or get a high directivity performance over broad bandwidth. We also apply the proposed structure to a half wavelength band pass filter and successfully cancel the first spurious passband. All the synthesis procedures of the proposed structure are described in detail. The second part presents a solution for miniaturizing microstrip loose coupler with high directivity.