具任意不等功率分配及阻抗轉換特性之半對稱鼠競環耦合器研製與量測

Abstract

本論文利用S-平面濾波器合成理論和功率分配理論的基礎，設計出具有寬頻、任意不等功率分配、高隔離度以及阻抗轉換特性之半對稱鼠競環耦合器。本論文之鼠競環耦合器是利用微帶線及增強耦合結構之耦合線所組成之平面電路，故在電路製造上是簡單且可靠的。 為了證實本論文所提出之鼠競環耦合器具任意不等功率分配率特性，本論文實作兩個具有不同功率分配率之鼠競環耦合器，分別為輸出功率分配比為3-dB(2：1)和10-dB(10：1)之耦合器，使用板材為介電常數3.55的Rogers RO4003，板材厚度為 20 mil，操作中心頻率為 2 GHz，操作頻寬100％，輸入阻抗50歐姆以及輸出阻抗70歐姆；另一方面，本論文也著墨在克服輸入和輸出阻抗不同的量測問題。

In this thesis, a half-symmetric rat-race ring coupler with broadband, arbitrary unequal power dividing, high isolation, and impedance transforming characteristics is proposed using S-domain filter synthesizing theorem and power dividing theorem. The rat-race ring coupler is a planar circuit consisted of microstrip lines and coupled line with enhanced coupling structures, which makes it simple to manufacture and reliable. In order to generalize the concept with arbitrary power dividing ratio, two rat-race ring couplers with different unequal power dividing ratio of 3-dB(2：1) and 10-dB(10：1) are designed and measured. The proposed rat-race ring couplers, with center frequency 2GHz, operating bandwidth 100%, input impedance 50 Ohm and output impedance 70 Ohm, are manufactured on a Rogers RO4003 substrate with dielectric constant of 3.55 and thickness of 20 mil. On the other hand, this thesis also emphasize on overcoming the problem of measuring the circuit with different input and output impedance.