本論文提出一適用於2.4 GHz 極小型無線網路收發器的雙緊鄰天線架構，在考慮接 近實際應用環境下，透過簡潔的設計概念並運用FR4 基板低成本且容易製作的優點，使 得此天線設計架構更貼近，也更為實用。首先，我們採用天線縮小化的方式來進行兩支 天線的設計，並針對緊鄰天線間的耦合效應來探討，可以發現其耦合效應約分為兩種，
一種為饋入點靠近的電感性耦合，而另一種為 PIFA 開路端之間的電容性耦合，由模擬 結果得知，電容性耦合影響隔離度較電感性耦合嚴重，在這麼狹小的設計空間裡，採用 了饋入點靠近的設計方法，並將 PIFA 開路端盡量遠離，接著為了進一步改善隔離度，
在兩天線中間設計一寄生元件，使其提供額外的耦合路徑來抵銷天線間原有的耦合量，
最後利用雙層疊板的架構設計，增加天線的設計空間，以提升雙緊鄰天線的輻射特性。
最終提出雙層雙緊鄰天線架構，其實際量測在反射損耗10 dB 以下的頻寬約有 83 MHz，
天線間最小隔離度約為8.54 dB，在全向性輻射場型平面的平均輻射增益可達-1.43 dBi，
模擬與實作結果皆符合2.4GHz 無線網路需求。
參考文獻
[1] Schulteis S., Waldschmidt, C., Sorgel, W., and Wiesbeck, W., “A Small Planar Inverted F Antenna with Capacitive and Inductive Loading,” in IEEE AP-Symp., vol. 4, pp.4148-4151, 2004.
[2] Y.-S. Wang, M.-C Lee, and S.-J. Chung, “Two PIFA-Related Miniaturized Dual-Band Antennas,” IEEE Tran. Antenna Propag., vol. 55, no. 3, pp. 805-811, March 2007.
[3] F. Yang and Y. R. Samii, “Microstrip antennas integrated with electromagnetic
band-gap EBG structures: a low mutual coupling design for array applications,” IEEE Trans. Antennas Propag., vol. 51, no. 10, pp. 2936-2946, Oct. 2003.
[4] Z. Iluz, R. Shavit, and R. Bauer, “Microstrip antenna phased array with electromagnetic bandgap substrate,” IEEE Trans. Antenna Propaga., vol. 52, no. 6, pp.1446-1453, June 2004.
[5] L. Yang, M. Fan, F. Chen, J. She, and Z. Feng, “A novel compact electromagnetic-bandgap (EBG) structre and its applications for microwavecircuits,”
IEEE Tran. Microwave Theory Tech., vol. 53, no. 1, pp.183-190, Jan. 2005.
[6] A. Diallo, C. Luxey, P. L. Thuc, R. Staraj, and G. Kossiavas, “Study and reduction of the mutual coupling between two mobile phone PIFAs operating in the DCS1800and UMTS bands,” IEEE Trans. Antennas Propag., vol. 54, no. 11, pp. 3063-3073, Nov. 2006.
[7] A. Diallo, C. Luxey, P. L. Thuc, R. Staraj, G. Kossiavas , M. Franzen, and P.-S.
Kildal, “MIMO performance of enhanced UMTS four-antenna structures for mobile phones in the presence of the user’s head,” in Proc. IEEE AP-S Int. Symp., Jun. 2007, pp.
2853-2856.
[8] A. Diallo and C. Luxey, "Estimation of the diversity performance of several two-antenna systems in different propagation environments," in IEEE AP-S Int. Symp., Jun. 2007, pp.
2642-2645.
[9] A. Diallo, C. Luxey, P. L. Thuc, R. Staraj, and G. Kossiavas, “Enhanced two-antenna structures for universal mobile telecommunications system diversity terminals, IET Microwaves, Antennas and Propagation, Vol. 2, no. 1, pp. 93-101, Feb. 2008.
[10] S. Ranvier, C. Luxey, P. Suvikunnas, R. Staraj, and P. Vainikainen, “Capacity enhancement by increasing both mutual coupling and efficiency: a novel approach,” in IEEE AP-Symp., Honolulu, Hawaii, June 2007.
[11] J. Andersen and H. Rasmussen, “Decoupling and descattering networks for antennas,”
IEEE Trans. Antennas Propag., vol. 24, pp. 841-846, Nov. 1976.
[12] C. Y. Chiu, C. H. Cheng, R. D. Murch, and C. R. Rowell, “Reduction of mutual coupling between closely-packed antenna element,” IEEE Tran. Antenna Propag., vol. 55, no. 6, pp.1732-1738, June 2007.
[13] M. Yamamoto and K. Itoh, “Behaviour of the parallel plate mode in a stripline slot-coupled patch antenna,” IEE Proc. Microw. Antennas Propag. vol. 147, no. 5, pp.
385-389, Oct. 2000. (phy 1 pat)
[14] S.-C. Chen, Y.-S Wang, and S.-J. Chung, “A decoupling technique for increasing the port isolation between two strongly coupled antennas,” IEEE Tran. Antenna Propag., vol.
56, no. 12, December 2008.
[15] A. Diallo, C. Luxey, P. L. Thuc, R. Staraj, G. Kossiavas , M. Franzen, and P.-S.
Kildal, “Enhanced two-antenna structures for universal mobile telecommunications system diversity terminals,” IET Microwave. Antenna Propag., February. 2008, pp.
93-101.
[16] A. C. K. Mak, C. R. Rowell, and R. D. Murch, “Isolation Enhancement Between Two Closely Packed Antennas,” IEEE Tran. Antenna Propag., vol. 56, no.11, pp.3411-3418, November 2008. [17] S. H. Yeh and K. L. Wong, “Dual-band F-shaped monopole antenna for 2.4/5.2 GHz WLAN application,” in IEEE AP-S Int. Symp. vol.4, June 2002, pp.72-75.
[17] S. H. Yeh and K. L. Wong, “Dual-band F-shaped monopole antenna for 2.4/5.2 GHz WLAN application,” in IEEE AP-S Int. Symp. vol.4, June 2002, pp.72-75.
[18] M.-D. Lin and S.-J. Chung, “A Compact MIMO antenna System with Three Closely Spaced Multi-band Antennas for WLAN,” in Microwave Conference, 2007. APMC 2007.
附錄 A (雙層具有去耦合雙天線之對位誤差影響)
在本論文第四章後段，我們探討了屏蔽盒高度與距離對雙層雙天線架構的影響，其 中所提出架構皆在，探討雙層疊板在x 軸上對位的誤差，示意圖如圖 A.4 所示，由 P 值 變化觀察圖A.5、A.6 可知，當 P 軸為 P = 0 mm，朝-x 軸方向偏移為負 P 值，而同理往 +x 軸方向偏移為正 P 值，這裡橫向對位的誤差，造成了設計的中心頻率微幅飄移，並 些許改善天線間隔離度，但透過天線增益模擬並無額外增加平均增益表現，所以我們更 加確定隔離度些許改善為天線阻抗匹配的影響，造成饋入能量部分損失而增加少許隔離 度，由本附錄探討可知，本論文所提出的雙層雙天線架構在對位的誤差上皆在設計的需 求頻段內，證明了此架構實作時的穩定性。
z y
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原有基板正面 疊板背面
P
z y
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原有基板正面 疊板背面
z y
x
z y
x
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原有基板正面 疊板背面
P
圖A.1 雙層具有去耦合之雙天線架構疊板對位誤差 P 變化示意圖
圖A.2 雙層具有去耦合之雙天線架構對位誤差 P 變化之模擬 S11 圖
圖A.3 雙層具有去耦合之雙天線架構對位誤差 P 變化之模擬 S21 圖
附錄 B (實作照片)
圖B.1 單層單一天線架構實體圖
圖B.2 單層使用 LTCC Chip antenna 之雙天線架構實體圖
圖B.3 單層饋入點靠近之雙天線架構實體圖 (正面)
圖B.4 單層饋入點靠近之雙天線架構實體圖 (背面)
圖B.5 單層饋入點遠離之雙天線架構實體圖 (正面)
圖B.6 單層饋入點遠離之雙天線架構實體圖 (背面)
圖B.7 雙層雙天線架構實體圖 (正面)
圖B.7 雙層雙天線架構實體圖 (背面)