38-GHz 無線收發系統關鍵元組件技術- 子計畫一:共面波導印刷電路二維天線陣列(2/3) ; 2-D CPW-Fed Pr inted Circuit Antenna Ar ray (2/3)

本計畫是三年期計畫的第二年。本年度主要是針對整合型計畫所需要之38 GHz，主波束寬為3 度之二維陣列天線進行設計。如第一年計畫中所提出之結 構，該陣列天線之特點為：可依應用之不同而設計成一維或二維之天線陣列，設 計上相當具有彈性。為了驗證頻率與天線特性的獨立性，本年度中我們設計了一 60GHz 的二維天線陣列，並以實作完成驗證。 隨著城垛形開槽陣列天線中輻射單元數目的增加，其輸入阻抗亦隨之增加， 造成輸入阻抗不匹配。對於輻射單元數不多的城垛形開槽陣列天線，我們可藉由 調整其槽線寬來達到輸入阻抗匹配的目的。若其輻射單元數過多，光靠縮小槽線 寬已無法達成阻抗匹配，於是我們加入一簡單的輸入阻抗之匹配電路。該匹配電 路在不影響天線效能的前提下，成功地將陣列天線的高輸入阻抗轉換至饋入共面 波導的特徵阻抗。為驗證城垛形開槽陣列天線之工作頻率對於天線特性與匹配電 路效能的影響，我們設計一12´2 之二維陣列天線及其輸入阻抗之匹配電路，由 實驗與模擬之比較結果顯示城垛形開槽陣列天線及匹配電路之實用性與可行 性，且天線特性與匹配情形不因工作頻率而有所改變。 ; This project is the second year of a three-year project. The final goal of this project is to design a CPW-fed planar array with 3-degree beamwidth at 38GHz. As presented in the first year, the CPW-fed rampart slot array had been proposed and studied feasibly. One attractive feature of this antenna array is that it can be designed as a linear or a planar array depending on the system requirements. A 60-GHz design is realized this year to verify the independence between the operating frequency and the radiation characteristics. As the number of radiating elements in a rampart slot array increases, the input impedance of the array increases as well. An impedance mismatch thus occurs. When less elements are used, it is easy to obtain a good input match by tuning the slotline width. However, when more elements are required, an input matching circuit must be applied. A simple matching circuit is used in our design, which successfully tunes the high input impedance of the array to match the characteristic impedance of the feeding CPW. To clarify our design and the relation between the operating frequency and radiation characteristics, a 60-GHz 12´2 planar array with a matching circuit is fabricated. From experiment and simulation results, the rampart slot array together with the matching circuit is proved to be practical and the performance is independent of the operating frequency.