Multiple-input and multiple-output (MIMO) is currently regarded as a key technology for long term evolution (LTE), but a critical effect is mutual coupling (S21) due to space constraint in miniaturized design. A compact-size antenna with low mutual coupling will be an ideal choice for better system performance. This paper describes the design of a small-size (48 × 48 mm2) MIMO antenna system with low mutual coupling for LTE 800 MHz applications. The antenna system comprises two FR-4 substrate layers; one printed with two meander line antennas (MLAs) and the other printed with reactive impedance surface (RIS) and defected ground structure (DGS). The properties of the antenna, such as S-Parameters, excited surface current distribution, far-field radiation pattern and diversity performance characteristics, were studied. The results indicated that MLAs rendered compactness to the system. Introduction of air gap (AG) between the two substrates, DGS and periodic square patches of RIS resulted in 452 MHz bandwidth and mutual coupling of -41.18 dB between antenna elements. The performance of the proposed design compared with other reported geometry has been demonstrated. Parameters including bandwidth, ratio of antenna area/improvement in S21, antenna efficiency and the envelope correlation coefficient were compared. Considering the results, the present system appears to be comparatively more efficient.
1. Garg, V. K., Wireless Communications and Networks, Morgan Kaufmann Publishers, Elsevier, 2007.
2. Larmo, A., M. Lindstrom, M. Meyer, G. Pelletier, J. Torsner, and H. Wiemann, "The LTE linklayer design," IEEE Communications Magazine, Vol. 47, No. 4, 52-59, Apr. 2009. doi:10.1109/MCOM.2009.4907407
3. Foschini, G. J. and M. J. Gans, "On limits of wireless communications in a fading environment when using multiple antennas," Wireless Personal Communications, Vol. 6, 311-335, Mar. 1998. doi:10.1023/A:1008889222784
4. Telatar, E., "Capacity of multi-antenna Gaussian channels," European Transactions on Telecommunications, Vol. 10, No. 6, 585-595, Nov. 1999. doi:10.1002/ett.4460100604
5. Ludwig, A., "Mutual coupling, gain and directivity of an array of two identical antennas," IEEE Transactions on Antennas and Propagation, Vol. 24, No. 6, 837-841, Nov. 1976. doi:10.1109/TAP.1976.1141440
6. Lau, B. K. and Z. Ying, "Antenna design challenges and solutions for compact MIMO terminals," IEEE International Workshop on Antenna Technology (iWAT), 70-73, Apr. 2011.
7. Yang, X. M., X. G. Liu, X. Y. Zhou, and T. J. Cui, "Reduction of mutual coupling between closely packed patch antennas using waveguided metamaterials," IEEE Antennas and Wireless Propagation Letters, Vol. 11, 389-391, Apr. 2012. doi:10.1109/LAWP.2012.2193111
8. Lee, C. H., S. Y. Chen, and P. Hsu, "Integrated dual planar inverted-F antenna with enhanced isolation," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 963-965, Aug. 2009.
9. Bait-Suwailam, M. M., O. F. Siddiqui, and O. M. Ramahi, "Mutual coupling reduction between microstrip patch antennas using slotted-complementary split-ring resonators," IEEE Antennas and Wireless Propagation Letters, Vol. 9, 876-878, Sep. 2010. doi:10.1109/LAWP.2010.2074175
10. Cheng, C., F. Zhang, Y. Wan, and F. Zhang, "Miniaturized high-isolation dual-frequency orthogonally polarized patch antenna using compact electromagnetic bandgap filters," International Journal of Antennas and Propagation, Apr. 2014.
11. Chen, S. C., Y. S. Wang, and S. J. Chung, "A decoupling technique for increasing the port isolation between two strongly coupled antennas," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 12, 3650-3658, Dec. 2008. doi:10.1109/TAP.2008.2005469
12. Zhao, L., L. K. Yeung, and K. L. Wu, "A coupled resonator decoupling network for two-element compact antenna arrays in mobile terminals," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 5, 2767-2778, May 2014. doi:10.1109/TAP.2014.2308547
13. Ghosh, J., S. Ghosal, D. Mitra, and S. R. Bhadra Chaudhuri, "Mutual coupling reduction between closely placed microstrip patch antenna using meander line resonator," Progress In Electromagnetics Research Letters, Vol. 59, 115-122, 2016. doi:10.2528/PIERL16012202
14. Ray, K. P., S. Ghosh, and K. Nirmala, "Multilayer multiresonator circular microstrip antennas for broadband and dual-band operations," Microwave and Optical Technology Letters, Vol. 47, 489-494, Dec. 2005. doi:10.1002/mop.21208
15. Guha, D. and J. Y. Siddiqui, "Resonant frequency of equilateral triangular microstrip antenna with and without air gap," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 8, 2174-2178, Aug. 2004. doi:10.1109/TAP.2004.832504
16. Li, L., Y. Yu, and L. Yi, "Mutual coupling reduction between printed dual-frequency antenna arrays," Progress In Electromagnetics Research Letters, Vol. 59, 63-69, 2016. doi:10.2528/PIERL16020601
17. Sievenpiper, D., L. Zhang, R. F. J. Broas, N. G. Alexopoulos, and E. Yablonovitch, "Highimpedance electromagnetic surfaces with a forbidden frequency band," IEEE Transactions on Microwave Theory Techniques, Vol. 47, 2059-2074, Nov. 1999.
18. Yeo, J. and R. Mittra, "Bandwidth enhancement of multiband antennas using frequency selective surfaces for ground planes," IEEE International Symposium on Antennas and Propagation Society, Vol. 4, 366-369, Jul. 2001.
19. Mosallaei, H. and K. Sarabandi, "Antenna miniaturization and bandwidth enhancement using a reactive impedance substrate," IEEE Communications Magazine, Vol. 52, No. 9, 2403-2414, Sep. 2004.
20. Marrocco, G., "Gain-optimized self-resonant meander line antennas for RFID applications," IEEE Antennas and Wireless Propagation Letters, Vol. 2, 302-305, Jan. 2003. doi:10.1109/LAWP.2003.822198
21., , 3GPP TS 36.101, V8.3.0, EUTRA User Equipment Radio Transmission and Reception, 2008.
22. Li, H., J. Xiong, and S. He, "A compact planar MIMO antenna system of four elements with similar radiation characteristics and isolation structure," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 1107-1110, Oct. 2009.
23. Min, K. S., D. J. Kim, and Y. M. Moon, "Improved MIMO antenna by mutual coupling suppression between elements," The European Conference on Wireless Technology, 125-128, Paris, France, Oct. 2005.
27. Karaboikis, M. P., V. C. Papamichael, G. F. Tsachtsiris, C. F. Soras, and V. T.Makios, "Integrating compact printed antennas onto small diversity/MIMO terminals," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 7, 2067-2078, Jul. 2008. doi:10.1109/TAP.2008.924677
28. Taga, T., "Analysis for mean effective gain of mobile antennas in land mobile radio environments," IEEE Transactions on Vehicular Technology, Vol. 39, 117-131, May 1990. doi:10.1109/25.54228
29. Taga, T., "Analysis of correlation characteristics of antenna diversity in land mobile radio environments," Electronics and Communications in Japan, Part I, Vol. 74, No. 8, 101-116, 1991. doi:10.1002/ecja.4410740810
30. Schwartz, M., W. R. Bennett, and S. Stein, Communication System and Techniques, 470-474, McGraw-Hill, New York, 1965.
31. Pierce, J. N. and S. Stein, "Multiple diversity with non independent fading," Proceedings of the IRE, Vol. 48, 89-104, Jan. 1960. doi:10.1109/JRPROC.1960.287384
32. Rao, Q. and K. Wilson, "Design, modeling and evaluation of a multiband MIMO/diversity antenna system for small wireless mobile terminals," IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 1, 410-419, Mar. 2011. doi:10.1109/TCPMT.2010.2101234
33. Zhang, S., A. A. Glazunov, Z. Ying, and S. He, "Reduction of the envelope correlation coefficient with improved total efficiency for mobile LTE MIMO antenna arrays: Mutual scattering mode," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 6, 3280-3291, Jun. 2013. doi:10.1109/TAP.2013.2248071
34. Lee, B., F. J. Harackiewicz, and H. Wi, "Closely mounted mobile handset MIMO antenna for LTE13 band application," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 411-414, Feb. 2014.
35. Yetisir, E., C. C. Chen, and J. L. Volakis, "Low profile UWB 2-port antenna with high isolation," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 55-58, 2014. doi:10.1109/LAWP.2013.2296045