印刷式螺旋天線與超寬頻饋入網路之圓極化整合設計

Abstract

本論文旨在設計及研製超寬頻螺旋天線與超寬頻饋入電路，以整合成超寬頻圓極化天線。首先，我們設計90°之耦合器，此元件之操作頻寬可涵蓋1.1 GHz至5.8 GHz。接著，我們提出180°之立體平衡器，且可達到1.2 GHz至6 GHz之頻寬。此外，我們亦設計阿基米德螺旋天線，此天線之模擬頻寬為2.5 GHz至8 GHz。 在驗證上，我們實做了四埠之90°耦合器、單一螺旋天線與180°之平衡器所組成之天線模組以及兩個螺旋天線結合兩個180°之平衡器與單一90°之耦合器而成之1 x 2序列式旋轉天線陣列。在量測方面，其結果均與模擬之趨勢一致，單一螺旋天線之整合可達到2.3 GHz至6.2 GHz之操作頻寬；而1 x 2序列式旋轉螺旋天線陣列之操作頻寬可涵蓋2 GHz至6 GHz。此外，在1 x 2序列式旋轉螺旋天線陣列之中，饋入網路裡耦合器之隔離埠可視為差分埠進行操作，並且可於正上方產生圓極化之差分場型，並搭配視為加總埠之耦合器輸入埠，此1 x 2天線陣列將可作為追蹤雷達與通訊之應用。

This thesis presents the design and implementation of both the ultra-wideband spiral antennas and the required ultra-wideband feeding circuits for the ultra-wideband circularly polarized operations. First, we designed a 90-degree directional coupler with a bandwidth covering 1.1 GHz to 5.8 GHz. Second, we proposed a compact folded 180- degree balun with a bandwidth range from 1.2 GHz to 6 GHz. Third, we designed an Archimedean spiral antenna with a differential feed covering the bandwidth between 2.5 GHz and 8 GHz. We built the prototypes for the design verification of the proposed designs, including the 4-port 90-degree directional coupler, the single spiral antenna integrated with the 180-degree balun, and the 1 x 2 antenna array of sequential rotation integrated with two 180-degree baluns and a 90-degree coupler. The experimental results are consistent with the simulated results for each developed prototypes. The single spiral antenna has an overlapped bandwidth of 2.3 GHz to 6.2 GHz. The 1 x 2 sequential rotation spiral antenna arrays also perform a decent bandwidth from 2 GHz to 6 GHz. Additionally, the isolated port of the coupler can operate as a Difference port that the radiation pattern is a CP difference pattern. Together with the input port as a Sum pattern, the developed 1 x 2 arrays can be used for the radar tracking and communication applications.