WiMAX 基地台 4-by-4 槽孔天線設計

Abstract

本文提出了利用微帶線饋入槽孔天線（slot antenna），來製做WiMAX頻段（3.4GHz至3.7GHz）的4X4槽孔陣列天線（slot array antenna）。將槽孔天線傾斜45度，使其4X4槽孔陣列天線的有兩個極化方向的輻射場，增強其抗干擾能力。採用並-串（parallel-series）聯饋送網路，縮短饋送路徑以減少能量損耗、整體陣列天線面積和在單位面積中能有著較多的槽孔天線個數。運用平面印刷電路技術在FR4基板上來製作4X4槽孔陣列天線且利用電磁模擬軟體HFSS模擬整個陣列天線結構，以降低成本和設計複雜度。 其量測結果顯示，在4X4槽孔陣列天線幅射場型上有高天線增益和窄的-3dB波束寬度。

In this thesis, a 4-by-4 two-dimensional slotted array antenna was designed, fabricated and measured. Such an array antenna consists of four series-fed sub-array antennas and a metal reflector for achieving single-side radiation. Moreover, the four sub-array antennas are fed by a 1-by-4 power divider made up of three 1-by2 power dividers. By the antenna theory, adjusting the progressive phase delay angle, the main beam angle can be steered toward any desired direction. In this research, the progressive phase delay angle is designed at 0 degree for obtaining the radiation main-beam toward broadside direction （perpendicular to the plan of slots）. Additionally, the slot inclines 45degree with respect to the micro-strip line for generating two polarized electric-field along two orthogonal directions. This may enhance the receiving performance in a complex environment. Due to the advantages of easy fabrication, robustness and low-cost issue, such an array antenna can be a potential candidate for serving a point-to point planar array antenna in WiMAX applications around 3.5GHz