本論文主要提出一個雙圓極化槽孔天線的設計，進而相繼提出一些圓極化天線的設計方法與概念，達到增進圓極化軸比頻寬的目的，並同時具有寬頻的 10-dB 阻抗頻寬和良好的隔離度。 首先以共平面波導槽孔天線做為研習，製作在介質基板 FR4 板材上，並利用兩個 T 形饋入端達成雙極化的特性。其次，為了改善兩端口之間的隔離度，在兩饋入線之間的槽孔加入不同形狀的接地金屬貼片，避免能量大量的耦合至另一饋入端。再者，藉由增加一些環狀或非對稱的接地金屬貼片架構，並調整其垂直與水平段金屬貼片長度，可以形成良好的圓極化操作，並且天線的圓極化和阻抗匹配可分別獨立完成。最後，適當的調整饋入線的架構，藉由改變金屬貼片形狀或長度，來優化天線的整體響應，使其能夠擁有寬頻的 10-dB 阻抗頻寬和圓極化軸比頻寬，完成寬頻雙圓極化槽孔天線的設計。 本論文所提出的電路皆由以上概念設計而成，於本文中將有電路的設計原理、參數分析、模擬結果與實作結果的比較。;The thesis will go through the process that how we designed the dual circularly polarized slot antennas. We proposed some design methods to improve the axial-ratio bandwidth, 10-dB impedance bandwidth and isolation simultaneously. First, we applied the design concept of a CPW-fed slot antenna, and fabricated on the FR-4 substrate. By using two T-shaped feeding lines to achieve the characteristics of dual polarization. At the next step, we added a grounded strip beside both two feeding lines to improve the isolation between these two ports. Then, by adding some ring-shaped or asymmetric grounded strips and adjusting the length of these vertical and horizontal strips, a good circular polarization operation can be formed. In the meanwhile, the circular polarization operation and impedance matching can be achieved independently. In the last step, we fined tune the structure of two feeding lines by changing their shapes and lengths to optimize the responses of the antenna. By applying all above processes, we successfully designed the dual circularly polarized slot antennas. All design methods, parameters analysis, comparison results between simulation and measurement are discussed and presented in the thesis.
