Ku頻段反射式類比移相器與縮小化寬頻阻抗轉換微波岔路環

Abstract

本論文前半部提出兩種適用於Ku頻帶的類比反射式移相器：一種是將可變電容二極體諧振並轉換阻抗使可移轉角度增加到280度，另一種是透過並聯兩個可變電容二極體的方式使可移轉角度超過360度。並且，本文利用此移相器設計了一個可調整天線主波束方向的相位陣列。 本論文後半部份設計一個中心頻率為3GHz的寬頻微波岔路環。在各輸出入埠加上額外的單位元件(unit element即為一段四分之一波長傳輸線)，可使頻寬接近100%並具有阻抗轉換功能(40歐姆到120歐姆)。結構上，利用歩階阻抗共平面帶線可以得到理想的反相器、壓制高頻諧波、和使體積縮小為原來的70%等優點。

In the first part, we propose two Ku band reflection-type phase shifters using four and two varactors to exhibit maximum phase shift of 360o and 286o, respectively. For a single varactor, the maximum phase shift is increased by resonating the varactor and impedance transforming at the input of the reflection load. The 360o phase shift results from the parallel connection of two series tuned varactors. A 4-element phased array is designed and fabricated to verify the phase shifter. In the second part, the 180o hybrid ring adding a unit element at each port has been designed to exhibit Chebyshev response and impedance transformation. We use hybrid CPS/interdigital CPS as stepped-impedance and ideal phase inverter for size reduction of 70% and wideband performance. The fabricated 180o hybrid ring exhibits a wide bandwidth of almost 100%, and its amplitude and phase balance are less than 0.55dB and 4 degree, respectively. For system impedance transformation of 40Ω and 120Ω, each port of the proposed 180o hybrid ring is well-matched.