增強圓型極化天線增益之研究

GAIN ENHANCEMENT FOR CIRCULARLY POLARIZED ANTENNAS

吳岷錡(Min-chi Wu)

指導教授 ： 張知難

大同大學/電機資訊學院/通訊工程研究所/碩士(2008年)

摘要

在本篇論文中，提出了一種由微帶線饋入的微帶線天線，此天線是被設計應用於2.45GHz的無線區域網路，而為了要提升微帶線天線的增益值，設計了一個天線罩放在微帶線天線的正前方，中間有空氣層。經模擬及實驗結果，且此天線罩可以提升微帶線天線的增益值，從原本的3.1 dBi增加為6.57dBi，其阻抗頻寬為80MHz，且空氣層的高度只有真空中波長的1/10。由HFSS模擬軟體的電場分佈，可以看出此天線罩具有聚焦的功能。
由於圓形極化天線能產生圓形極化波，可以進一步改善接收訊號的能力。 故在本篇文章中也設計了一個應用於2.45GHz的圓形極化微帶線天線，並且也設計了一個新的天線罩用於此圓形極化天線，這一個新的天線罩不但可以提升圓形極化天線的增益值並且可以維持圓形極化天線的3dB軸比寬。天線增益值由3dBic增加為7.1dBic，3dB軸比寬約為25MHz，阻抗頻寬為146MHz。

關鍵字

圓型極化 ； 微帶線天線 ； 線性極化

並列摘要

In this thesis, a microstrip patch antenna fed by a microstrip line is represented. This microstrip patch antenna is designed at 2.45GHz for wireless local area network (WLAN). The goal of this thesis is to enhance gain of microstrip antenna. An antenna radome is proposed to increase the gain of microstrip patch antenna and there is an air gap which is only 0.1 between two substrates. From simulation and measurement results, the gain of microstrip patch antenna with a radome increases 3.47dBi from 3.1dBi to 6.57dBi, and impedance bandwidth is 80MHz. Field distributions shows that the radome has a congregation effect on the radiation of the electromagnetic waves.
Due to the circularly polarization patch antenna can improve the ability of transmitting and receiving. A circularly polarization patch antenna is also investigated. A novel antenna radome is proposed for this circularly polarization patch antenna. This antenna radome not only increases the gain but also maintains the axial ratio. The gain is enhanced from 3dBic to 7.1dBic, axial ratio bandwidth is about 25MHz, and impedance bandwidth is 146MHz.

並列關鍵字

microstrip patch antennas ； linear polarization ； circular polarization ； gain enhancement

參考文獻

[5] R. Munson, “Conformal microstrip antennas and microstrip phased arrays,” Antennas and Propagation, IEEE Transactions on., Volume 22, Issue 1, pp(s):74–78, Jan 1974.

[6] L. Shen, S. Long, M. Allerding and M. Walton, “Resonant frequency of a circular disc, printed-circuit antenna,” Antennas and Propagation, IEEE Transactions on., Volume 25, Issue 4, pp(s):595–596, Jul 1977.

[7] D. R. Jackson and N. G. Alexopoulos, “Gain enhancement methods for printed circuit antennas,” Antennas and Propagation, IEEE Transactions on., Volume 33, Issue 9, pp(s):976–987, Sep 1985.

[8] N. G. Alexopoulos and D. R. Jackson, “Fundamental Superstrate Effects on Printed Circuit Antenna Efficiency,” Microwave Symposium Digest, MTT-S International., Volume 84, Issue 1, pp(s):475–476, May 1984.

[9] R. Q. Lee, K. F. Lee and J. Bobinchak, “Characteristics of a two-layer electromagnetically coupled rectangular patch antenna,” Electronics Letters., Volume 23, Issue 20, pp(s):1070–1072, September 24 1987.