微帶線饋入之雙頻帶準八木天線設計

針對用微帶線饋入應用在雙頻的準八木(quasi-Yagi)天線，本論文提出了一個原始的以及一個改良的設計。在現在的生活中，此天線可廣泛應用在點對點無線通訊上。這兩個小型且製作在FR4雙層板的雙頻準八木天線，在兩個操作頻率上都擁有端射(end fire)的輻射場型。這兩個結構組成的元件皆為一對分別由微帶線向兩個方向伸出的雙偶極天線，一個導向體(director)元件，以及一個被截掉的接地面視為一個反射體(reflector)。　　應用在無線區域網路(WLAN) 802.11a/b/g上，原始的設計經由量測可得到在低頻的頻帶上有3.6%的頻寬，天線增益變化約3.6 - 4.7 dBi，在高頻頻帶有27.6%的頻寬，天線增益變化約5.2 - 6.2 dBi。而改良後的設計量得低頻有9.2%的頻寬以及5.6 - 6.2 dBi的天線增益變化，高頻則有48.4%的頻寬和5.1 - 7.6 dBi的天線增益變化。這兩個設計在他們的操作頻帶裡都可得到大於10 dB的前後輻射比(front-to-back ratio)，以及小於-10dB的正交極化位準。相關模擬和量測的結果在本論文都有詳細的呈現及討論。

關鍵字

雙頻帶, 準八木天線, 端射

並列摘要

The original and modified designs of the microstrip-fed quasi-Yagi antennas for dual frequency operation are proposed in this thesis. They can be widely applied to point to point wireless communications in modern life. The two compact and double-layered dual band quasi-Yagi antennas fabricated on the FR4 substrate have end-fire radiation patterns within their two frequency bands. Both two structures consist of two arms of two driving dipoles connected separately to two microstrip sections, a director element, and a truncated ground plane as a reflector element. For WLAN application of IEEE 802.11a/b/g, the original design measures the bandwidths of 3.6 % with gain variations of 3.6 – 4.7 dBi in the lower band and 27.6% with 5.2 – 6.2 dBi in the upper band. The modified design measures the bandwidth of 9.2 % with gain variations of 5.6 – 6.2 dBi in the lower band and 48.4 % with 5.1 – 7.6 dBi in the upper band. For these two designs, better than 10dB front-to-back ratios, and lower than -10dB cross-polarization levels within their operating frequency bands are obtained. Details of simulation and measurement results are presented and discussed.

並列關鍵字

Dual-band, Quasi-Yagi antenna, End-fire

參考文獻

[1] Y. Qian, W. Deal, N. Kaneda, and T. Itoh,“Microstrip-fed quasi-Yagi antenna with broadband characteristics,” Electronics Lett., vol. 34, no. 23, pp. 2194-2196, Nov. 1998.

[2] N. Kaneda, W. Deal, R. Waterhouse, Y. Qian, and T. Itoh, “A broad-band planar quasi-Yagi antenna,”IEEE Trans. Antenna Propagat., vol. 50, no. 8, pp. 1158-1160, Aug. 2002.

[3] H. Yagi, “Beam transmission of the ultra short waves,” Proc. IRE, vol.16, pp. 715–741, June. 1928.

[4] J. Huang, “Planar microstrip Yagi array antenna,” in IEEE Antennas and Propagation Society Int. Symp., Jun. 1989, vol. 2, pp. 894–897.

[5] A. Densmore and J. Huang, “Microstrip Yagi antenna for mobile satellite service,” in IEEE Antennas and Propagation Society Int. Symp., Jun. 1991, vol. 2, pp. 616–619.

國際替代計量

微帶線饋入之雙頻帶準八木天線設計

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