無線區域網路雙頻天線之設計與分析

Design and Analysis of The Dual-Band Antennas for WLAN Communications

蔡皆得(Chieh-De Tsai)

指導教授 ： 黃啟芳

大同大學/電機資訊學院/通訊工程研究所/碩士(2004年)

摘要

本論文的內容在於針對雙頻天線在有限尺寸的地平面上,對其阻抗頻寬和輻射場型等特性作研究與探討。吾人認為,因應無線通訊產品,多頻段天線勢必為無線區域網路重要零件之一。本文即針對現今無線區域網路IEEE802.11a/b/g多頻段所需求之阻抗頻寬、輻射場型和增益變動做設計與分析。
首先，利用一矩形微帶天線配合槽孔,用單一Probe作饋入,依理論計算找出其最佳共振頻率，接著以模擬程式(IE3D)模擬求證是否準確,再依需要調整其共振頻率和最佳饋入位置。再以印刷電路板的製作方式，雕刻出天線的形狀，利用網路分析儀量測其Return loss及阻抗頻寬。這其中試用很多方法以克服Patch 天線天先性狹頻之特性一般因應IEEE802.11a全頻段必須有700MHz之頻寬，即從5150-5350MHz、5470-5825MHz。
緊接著研究以單極天線為架構，設計一個微小尺寸雙頻天線，應用於無線區域網路達到IEEE802.11a/b/g雙頻需求。為達其天線全向性特別將地平面尺寸縮小，並在電波無反射室中測量得到其場型。依所設計各種天線作模擬與實際量測，含阻抗頻寬、輻射場型和天線增益變動分析，最後所得結果除矩形微帶槽孔天線在較高頻段無法達到全頻段要求外，其餘所設計的天線之輻射場型和增益變動皆可適用於IEEE802.11a/b/g無線區域網路之應用。

關鍵字

矩型微帶天線 ； 探針 ； 單極天線 ； 高速區域網路 ； 無線區域網路雙頻天線

並列摘要

We have investigated and analyzed the characteristics of the impedance bandwidth and radiation patterns of limited-size dual-band antennas with a small ground plane. With the development of the state-of-the-art wireless communication products, the multi-band antennas must be ones of the most important components for Wireless Local Area Networks (WLAN) applications. Thus the limited-size dual-band antennas designed and presented in this thesis are to focus on the purposes of the modern IEEE802.11a/b/g WLAN applications. At higher frequency band (5GHz), the patch antenna could only be used in part of the IEEE802.11a band. To satisfy the requirement of the IEEE802.11a standard (5150–5350 and 5470–5825MHz), the bandwidth of at least 700MHz is required. Due to the above disadvantages of the patch antenna, small-size dual-band antennas with monopole structures are designed for the IEEE802.11a/b/g WLAN applications. The ground plane is minimized to achieve the omni-directional characteristics. The simulated and measured results of the impedance bandwidth, radiation patterns, and antenna gain variation of the antennas are analyzed. All the properties of these dual-band antennas including the bandwidth, radiating patterns, and gain variation can satisfy the IEEE 802.11a/b/g specifications for WLAN applications, except the rectangular microstrip antenna operating at higher frequency band due to its nature.

並列關鍵字

HIPERLAN ； ISM ； Monopole Antenna ； Probe ； Rectangular Patch Antenna ； WLAN

參考文獻

[1] W. Yajun and L. C. Kwang, “One Novel Single-Patch Dual-Frequency Planar Inverted-F Antenna,” in Proce.2000 IEEE –Internation Conf. On Microwave and Millimeter Wave Technology, pp. 444-447.

[2] Y-L. Kuo and K. L. Wong, “Print Double-T Monopole Antenna for 2.4/5.2 GHz Dual-Band WLAN Operations,” IEEE Trans. Antennas Propagat., Vol. 51, pp. 2187-2192, Sept. 2003.

[3] M. Ali, M. Okoniewski, M.A. Stuchly and S.S. Stuchly, “A Dual-Frequency Strip-Sleeve Monopole Antenna for a Laptop computer,” in IEEE AP-S Int. Symp., Digest, pp. 794-797, 1998.

[4] M. Sanad, “Microstrip Antennas on very small ground planes for portable communication systems,” in IEEE AP-S Int. Symp., Digest, pp. 810-813, 1994.

[7] I-F. Chen and C.-M. Peng, “Microstrip Fed Dual-U Shaped Printed Monopole Antenna for Dual-Band Wireless Communication Applications,” Electronics. Letters., Vol. 39, pp. 955-956, Jun. 2003.