結合寄生U型隙孔與矩形槽孔之寬頻圓極化天線設計

Broadband Circularly Polarized Antenna Design with Parasitic U-slot and Rectangular Aperture

余明哲(Ming-Je Yu)

指導教授 ： 林怡成

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10519

摘要

本論文提出了應用在印刷電路板上之結合寄生U型隙孔與矩形槽孔之寬頻圓極化天線。此天線架構由U型隙孔、矩形槽孔、反射板和饋入微帶型之傳輸線所組成。其中寄生U型隙孔控制高頻圓極化，而低頻圓極化則由矩形槽孔所主導，適當地將U型隙孔和矩形槽孔之共振頻帶做適當的整合設計，可以達到寬頻的特性。我們將透過參數分析來說明此設計的細節。此外，吾人更進一步在輻射元件背部加上反射板，來達到單向輻射的效果。最後，我們提出了對等式之雙元件架構，進一步改善輻射場型的頻寬和穩定度。因其天線架構的對稱性，使對等式的磁流分布可以產生比單一元件下更具對稱的輻射場型。本論文所提出的幾種天線架構都包含設計和實作，所呈現的模擬和量測結果皆具有一致性。在所有天線當中，最好的效能在S11< -10dB的反射係數頻寬約為23.8%，而AR < 3dB的頻寬約為21.8%，其頻寬能有效地涵蓋無線區域網路WLAN（IEEE 802.11a）的操作頻段5~6GHz。

關鍵字

圓極化天線 ； 反射板 ； 隙孔天線 ； 槽孔天線 ； 寬頻天線

並列摘要

This thesis presents the design of broadband circularly polarized antenna with parasitic U-slot and rectangular aperture in PCB structure. The antenna configuration consists of a U-slot, a rectangular aperture, and a backed reflector fed by a microstrip transmission line. The parasitic U-slot determines the upper band resonance while the rectangular aperture dominates the lower frequency band. Combining the U-slot and rectangular aperture with closed resonant bands, we can achieve the wideband CP operation. We describe the design details through the parametric study. In addition, a reflector is placed under the radiating element to achieve unidirectional radiation pattern. At last, we propose a two-element structure as a dual version of the proposed antenna that may further improve the bandwidth and stability of radiation patterns. By the symmetry of antenna geometry, the dual magnetic currents may generate more symmetric radiation patterns than the single element. The proposed antennas are successfully designed, implemented, and measured. Promising antenna performances are achieved, including 10-dB return loss bandwidth of 23.8% and 3-dB axial ratio bandwidth of 21.8%, covering the entire band of 5~6GHz for IEEE 802.11a WLAN System.

並列關鍵字

Circularly polarized antenna ； reflector ； slot antenna

參考文獻

[1] H. Morishita, K. Hirasawa, and K. Fujimoto, “Analysis of a cavity-backed annular slot antenna with one point shorted,” IEEE Trans. Antennas Propagate, vol. 39, pp.

[2] S. Shi, K. Hirasawa, and Z. C. Chen, “Circularly polarized rectangularly bent slot antennas backed by a rectangular cavity ,” IEEE Trans. Antennas Propagate, vol.

[3] R. L. Li, G. DeJean, J. Laskar, and M. M. Tentzeris, Investigation of circularly polarized loop antennas with a parasitic element for bandwidth enhancement”IEEE Trans. Antennas Propagate., vol. 53, no. 12, pp. 3930-3939, Dec. 2005

[5] R. L. Li, S. Basat, A. Traille, J. Laskar and M. M. Tentzeris, “Development of wideband circularly polarized square- and rectangular-loop antennas,” IEE Proc.-Microw. Antennas Propagate, vol. 153, no. 3, pp. 293–300, June 2006.

[6] R. L. Li, A. Traille, J. Laskar, and M. M. Tentzeris, “Bandwidth and gain improvement of a circularly polarized dual- rhombic loop antenna,” IEEE Antennas wireless Propagate Lett., vol. 5, no. 1, pp. 84-87, Dec. 2006.