由於行動裝置傳輸速率提升的要求，為支援高階無線通訊技術，須將多支天線擺放於有限的空間之內，因此需解決天線之間的耦合問題。
本論文提出一款緊湊式布建之雙天線解耦合架構，可以在筆電基底或平板側邊設置槽孔環境來進行解耦合。首先利用雙天線場型分集的特性，微調天線間平行錯位的距離，減少輻射耦合的影響；再來搭配建構之槽孔環境，延長天線的傳導電流路徑，使其相互抵消，達到降低傳導耦合的效果。使緊湊放置之雙天線隔離度提升。吾人透過實作，量測S參數與輻射效率，驗證解耦合架構的效果。
以上述解耦合技術為基礎，吾人設計一款適用於解耦合槽孔的WLAN雙頻段IFA天線，並在槽孔內新增高頻傳導電流路徑的不連續點，使高頻段的電流也能經由解耦合槽孔延長傳導路徑，達到抵消的效果。因此於WLAN雙頻段中，皆能觀察到耦合零點，驗證雙頻解耦合的效果。實做的反射係數、隔離度與輻射效率皆達到筆電產品應用的標準。

Due to the increased requirements of wireless transmission rate, multiple antennas on mobile devices must be placed in a limited space to support advance wireless communication technologies. Therefore, the coupling issue between antennas must be resolved.
This paper proposes a compact dual-antenna decoupling architecture that can work at a slot environment set up at the notebook’s side. In order to increase the isolation of two compactly displaced antennas, pattern diversity is first used to reduce radiation coupling. Then, to reduce conduction emission coupling, conduction currents are canceled by extending their paths in the loop environment. Measured S-parameter and radiation efficiency spectra verify that the decoupling architecture can effectively improve the isolation.
Based on the propose decoupling technique, a dual-band WLAN IFA antenna is designed, which is suitable for decoupling uses in slot environment. Furthermore, by adding geometric discontinuities for the high-frequency conduction current path in the slot, the currents can achieve a mutual canceling effect. Therefore, decoupling nulls can be observed in both WLAN bands. Through implementation, the performance of the compact antenna built in the decoupling slot is verified. The reflection coefficient, isolation and radiation efficiency performances can satisfy the application specifications of notebook products.

[1] W. C. Y. Lee, “Antenna spacing requirement for a mobile radio base-station diversity,” Bell Syst. Tech. J., vol. 50, pp. 1859-1876, July/Aug. 1971.
[2] J.-H. Lu, Y.-H. Liu, and H.-M. Chin, “Planar dual-band slot array antenna for LTE / WiMAX access points,” in Proc. IEEE International Symposium on Antennas and Propagation Conference Proceedings, 2014, pp. 331-332.
[3] A. Honda, I. Ida, Y. Oishi, Q. T. Tran, S. Hara, and J. Takada, “Experimental evaluation of MIMO antena selection system using RF-MEMS switches on a mobile terminal,” in Proc. IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007, pp. 1-5.
[4] Y. Li, H. Zou, M. Peng, M. Wang, and G. Yang, “Hybrid 12-antenna array for quad-band 5G/Sub-6GHz MIMO in micro wireless access points,” in Proc. IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), 2018, pp. 1-3.
[5] Y. Sharma, D. Sarkar, K. Saurav, and K. V. Srivastava, “Three-element MIMO antenna system with pattern and polarization diversity for WLAN applications,” IEEE Antennas Wireless Propag. Lett., vol. 16, pp. 1163 - 1166, Nov. 2016.
[6] C.-F. Ding, X.-Y. Zhang, C.-D. Xue, and C.-Y.-D. Sim, “Novel pattern-diversity-based decoupling method and its application to multielement MIMO antenna,” IEEE Trans. Antennas Propag., vol. 66, no. 10, pp. 4976 - 4985, Jun. 2018.
[7] X. Wang, Z. Feng, and K.-M. Luk, “Pattern and polarization diversity antenna with high isolation for portable wireless devices,” IEEE Antennas Wireless Propag. Lett., vol. 8, pp. 209 - 211, Aug. 2008.
[8] C.-Y. Huang and K.-L. Wong, “Side-edge LTE hybrid open-slot/inverted-F antenna with a narrow ground clearance for the smartphone,” in Proc. IEEE 5th Asia-Pacific Conference on Antennas and Propagation (APCAP), 2016, pp. 101-102.
[9] C.-Y. Chiu, C.-H. Cheng, R. D. Murch, and C. R. Rowell, “Reduction of mutual coupling between closely-packed antenna elements,” IEEE Trans. Antennas Propag., vol. 55, no. 6, pp. 1732 - 1738, Jun. 2007.
[10] J. Dong, X. Yu, and L. Deng, “A decoupled multiband dual-antenna system for WWAN/LTE smartphone applications,” IEEE Antennas Wireless Propag. Lett., vol. 16, pp. 1528 - 1532, Jan. 2017.
[11] Y. Yang, X. Ding, J. Ding, and Z. Zhao, “Decoupled dual-band slot antenna with bidirectional patterns for WLAN applications,” in Proc. IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2018, pp. 671-672.
[12] A. Ramachandran, S. V. Pushpakaran, M. Pezholil, and V. Kesavath, “A four-port MIMO antenna using concentric square-ring patches loaded with CSRR for high isolation,” IEEE Antennas Wireless Propag. Lett., vol. 15, pp. 1196 - 1199, Nov. 2015.
[13] H.-T. Hu, F.-C. Chen, and Q.-X. Chu, “A compact directional slot antenna and its application in MIMO array,” IEEE Trans. Antennas Propag., vol. 64, no. 12, pp. 5513 - 5517, Oct. 2016.
[14] Y. Liu, Y. Lu, Y. Zhang, and S.-X. Gong, “MIMO antenna array for 5G smartphone applications,” in Proc. 13th European Conference on Antennas and Propagation (EuCAP), 2019, pp. 1-3.
[15] S.-J. Lee, S.-H. Kim, K.-J. Lee, and Y.-S. Kim, “MIMO antenna using a ground plane protruding for WCDMA application,” in Proc. Asia-Pacific Microwave Conference, 2011, pp. 574-577.
[16] Y.-L. Ban, S. Yang, Z. Chen, K. Kang, and J. L.-W. Li, “Decoupled planar WWAN antennas with t-shaped protruded ground for smartphone applications,” IEEE Antennas Wireless Propag. Lett., vol. 13, pp. 483 - 486, Mar. 2014.
[17] P. Jwalitha, A. Nagasree, B. Lavanya, C. Yamuna, and K. V. Jyothi, “Design and analysis of decoupled multiband dual antenna for wireless applications,” in Proc. Second International Conference on Computing Methodologies and Communication (ICCMC), 2018, pp. 623-626.
[18] Y.-L. Ban, Z.-X. Chen, Z. Chen, K. Kang, and J. L.-W. Li, “Decoupled closely spaced heptaband antenna array for WWAN/LTE smartphone applications,” IEEE Antennas Wireless Propag. Lett., vol. 13, pp. 31 - 34, Dec. 2013.
[19] D. Sipal, M. P. Abegaonkar, and S. K. Koul, “Highly isolated compact planar dual-band antenna with polarization/pattern diversity characteristics for MIMO terminals,” IEEE Antennas Wireless Propag. Lett., vol. 18, no. 4, pp. 762 - 766, Apr. 2019.
[20] 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 DCS1800 and UMTS bands,” IEEE Trans. Antennas Propag., vol. 54, no. 11, pp. 3063 - 3074, Nov. 2006.
[21] G. Park, M. Kim, T. Yang, J. Byun, and A. S. Kim, “The compact quad-band mobile handset antenna for the LTE700 MIMO application,” in Proc. IEEE Antennas and Propagation Society International Symposium, 2009, pp. 1-4.
[22] R. A. Bhatti, S. Yi, and S.-O. Park, “Compact antenna array with port decoupling for LTE-standardized mobile phones,” IEEE Antennas Wireless Propag. Lett., vol. 8, pp. 1430 - 1433, 2009.
[23] C.-T. Lee, “Printed multi-antenna isolation improvement using decoupling network for USB dongle application,” in Proc. International Symposium on Antennas and Propagation Conference Proceedings, 2014, pp. 447-448.
[24] L. Mouffok, “A pattern diversity antenna with decoupling ports for LTE mobile phone,” in Proc. IEEE Antennas and Propagation Society International Symposium (APSURSI), 2014, pp. 681-682.
[25] Y.-F. Cheng and K.-K. M. Cheng, “A novel and simple decoupling method for a three-element antenna array,” IEEE Antennas Wireless Propag. Lett., vol. 16, pp. 1072 - 1075, Oct. 2016.
[26] G. Bauch and A. Alexiou, “MIMO technologies for the wireless future,” in Proc. IEEE 19th International Symposium on Personal, Indoor and Mobile Radio Communications(PIMRC 2008), 2008, pp. 1-6.
[27] H. Kim, Orthogonal Frequency‐Division Multiplexing, New York: Wiley Telecom, 2015.
[28] H.-D. Tang, Development of Decoupling Technique for Compactly Displaced Antennas Using Notebook Hinge Structure, M. S. thesis, National Taiwan University of Science and Technology, Taipei, Taiwan, 2018.
[29] Institute of Electrical and Electronic Engineers 802 LAN/MAN Standards Committee, IEEE standard for information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks-specific requirements, IEEE Std. 802.11, 2007.
[30] Institute of Electrical and Electronic Engineers 802 LAN/MAN Standards Committee, IEEE Standard for Information Technology—Local and Metropolitan Area Networks—Specific Requirements, IEEE Std. 802.11n-2009, 2009.