[[alternative]]Two Novel Fresnel Zone Lens Antennas

碩士電子工程學系[[abstract]]此論文當中，我們特別著重於天線繞射場型波束集中特性之研究，藉由激發源（環形天線）擺放不同位置，再由設計的天線結構產生想要的波束集中效果，而傅瑞涅耳天線的基本原理是物理光學中的繞射和干涉現象。因為傳統的平面結構傅瑞涅耳天線具有明顯的背向散射，所以我們設計新的結構，並佐以電磁模擬軟體來驗證進行，其相關參數如環帶、焦點、聚焦深度、相位修正等之間的關係與增益、效率、旁波瓣、背向反射的評估計算，並且找出適當的饋入位置，以得到想要的波束集中效果，我們提出利用多面正交之傅瑞涅耳環帶平面，或利用不同深度的階梯式傅瑞涅耳環帶形成的結構，達到高增益、低旁波瓣、及波束掃瞄的目的。[[abstract]]In this thesis, we want to develop a Fresnel zone antenna with high gain, low sidelobe and beam steering. We start from the Fresnel diffraction theory and develop the full-wave analysis, and then we can calculate the radiation pattern with physical optics. The important parameters such as focus, depth of focus, phase reversal of Fresnel zone and the relations between these parameters and antenna gain, efficiency, mainbeam,sidelobes. We also use commercial electromagnetic software to verify the simulation.We propose two new Fresnel zone structure. First are the use of the three mutual orthogonal Fresnel zone antenna. Second is stairway of Fresnel zone lens antenna