60GHz循序旋轉饋入圓極化陣列天線

Abstract

中文摘要 圓形極化波由於在傳輸時具有抑制多重路徑干擾的特點而廣泛被運用於無線通訊系統中。波束切換天線陣列則可於數個預先設計的輻射場型間進行切換，以達到更好的傳輸效果，並抑制多重路徑干擾。基於架構簡單、成本低廉之考量，吾人選擇以微帶塊狀陣列天線結合微帶線巴特勒矩陣來實現圓極化之波束切換天線模組於單一基板上。由於微帶塊狀天線的窄頻限制，吾人採用循序旋轉饋入法以增加其圓形極化之工作頻寬，並完成陣列設計。為了結合巴特勒矩陣，並確保波束切換之場型滿足系統需求，前述圓極化陣列天線之間距因而受限，吾人便設計了寬度縮減之圓極化微帶塊狀陣列天線，且整合於波束切換天線模組中，相關設計均透過實驗驗證。 本論文提出一簡單的計算方法，以有效預估循序旋轉饋入之陣列天線的阻抗及軸比響應。吾人利用該方法證實：比起只使用一次循序旋轉饋入之陣列，使用兩次循序旋轉饋入之陣列天線具有更寬頻的阻抗及軸比響應。基於上述結論，吾人設計出一系列寬頻且高增益之微帶陣列天線，並以實作驗證。

Abstract Recently, the circular polarization has been widely used in many wireless communication systems because of its ability to reduce the unwanted multi-path interference. And the switched-beam antenna array having several pre-designed fixed beam patterns can achieve better transmission performances and suppress the multi-path interference. Due to the simple structure and the low cost, the microstrip patch arrays have been chosen to integrate with the Butler matrix to achieve the circularly-polarized switched-beam antenna module on the same substrate. Owing to the inherently narrow bandwidth of the microstrip patch antennas, the sequential rotation technique has been used to enhance the operating bandwidth of the circularly-polarized patch antenna as well as the associated array. For integration with the Butler matrix and the switched-beam radiation patterns to satisfy the system requirements, a width-reduced circularly-polarized patch array is proposed. Then it is used as the array elements in the switched-beam antenna module. All the designs are verified theoretically and experimentally. In this thesis, a simple method for calculating the axial-ratio and impedance responses of a sequentially-rotated antenna array has been proposed. It has been demonstrated that applying the sequential rotation technique twice would result in a wider operating bandwidth than applying only once. Based on the discussions in the thesis, several broadband and high-gain patch arrays have been designed, implemented, and tested.