個人通訊系統基地台天線之研發

Abstract

本論文提出一個雙線性極化的基地台陣列天線。此天線工作在個人通訊系統的頻帶 (1850MHz-1990MHz)﹐在頻帶範圍內駐波比小於1.5。兩個垂直的極化方向分別傾斜±45°。此陣列天線包含數個隙孔耦合微帶天線﹐饋入方式是採用微帶線並饋網路。在每個天線元素上使用一個對稱饋入的結構可達成雙埠之間超過30dB的隔絕度。此外﹐一個金屬反射板被適當的放置在陣列天線後面來抑制背面的幅射並增加前後幅射比。我們製造並量測了兩個﹐四個﹐和八個元素的陣列天線。好的性能已經達成。每一陣列在垂直方向有窄的波束寬度(視元素數目而定)而在水平方向上大約有65°的寬度。

In this thesis, the design of a dual linearly polarized array antenna for base stations is presented. The antenna operates in the personnel-communication-system (PCS) band (1850MHz-1990MHz) with VSWR < 1.5. The two orthogonal polarizations are ±45°slanted. The array consists of several aperture-coupled microstrip patch elements fed by a microstrip corporate feeding network. A symmetrical feeding structure for each patch element is proposed and used to achieve good isolation (larger than 30dB) between the two orthogonal ports. In addition, to suppress the back radiation and increase the front-to-back ratio, a metal reflector is suitably placed behind the array antenna. Arrays with two, four, and eight antenna elements are fabricated and measured. Good performances have been achieved. Each array has a narrow beamwidth (depending on the element number) in the vertical direction and a beamwidth of about 65°in the horizontal direction.