In this paper, the mutual coupling from a multiple-input-multiple-output (MIMO) rim antenna has been utilized to control the level of specific absorption rate (SAR), when the mobile handset comes in close contact to the human body. The proposed antenna is capable of operating at 2.1 GHz and 4.3 GHz, respectively. A periodic defective ground structure (DGS) in conjunction with diodes and capacitors are used to manipulate the coupling between antenna elements. The working of the proposed dual band antenna design is validated using the characteristic mode analysis (CMA), and the current distribution. The MIMO performance is studied by using envelope correlation coefficient (ECC) and loss in capacity analysis. The effect of hand and LCD on the antenna performance is shown. The SAR analysis shows up to 30% reduction, in comparison to the baseline value of the SAR of the proposed antenna design.
1. Li, W., W. Lin, and G. Yang, "A compact MIMO antenna system design with low correlation from 1710 MHz to 2690 MHz," Progress In Electromagnetics Research, Vol. 144, 59-65, 2014. doi:10.2528/PIER13111305
2. Ren, A., et al., "A compact building block with two shared-aperture antennas for eight-antenna MIMO array in metal-rimmed smartphone," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 10, 6430-6438, 2019. doi:10.1109/TAP.2019.2920306
3. Sun, L., Y. Li, Z. Zhang, and Z. Feng, "Wideband 5G MIMO antenna with integrated orthogonalmode dual-antenna pairs for metal-rimmed smartphones," IEEE Transactions on Antennas and Propagation, Vol. 68, No. 4, 2494-2503, 2019. doi:10.1109/TAP.2019.2948707
4. Ban, Y.-L., et al., "4G/5G multiple antennas for future multi-mode smartphone applications," IEEE Access, Vol. 4, 2981-2988, 2016. doi:10.1109/ACCESS.2016.2582786
5. Wong, K.-L., C.-Y. Tsai, J.-Y. Lu, D.-M. Chian, and W.-Y. Li, "Compact eight MIMO antennas for 5G smartphones and their MIMO capacity verification," 2016 URSI Asia-Pacific Radio Science Conference (URSI AP-RASC), 1054-1056, IEEE, 2016. doi:10.1109/URSIAP-RASC.2016.7601145
6. Jamshed, M. A., F. Heliot, and T. W. Brown, "A survey on electromagnetic risk assessment and evaluation mechanism for future wireless communication systems," IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, Vol. 4, No. 1, 24-36, 2019. doi:10.1109/JERM.2019.2917766
7. Kitra, M. I., C. J. Panagamuwa, P. McEvoy, J. C. Vardaxoglou, and J. R. James, "Low SAR ferrite handset antenna design," IEEE Transactions on Antennas and Propagation, Vol. 55, 1155-1164, Apr. 2007. doi:10.1109/TAP.2007.893370
8. Wang, J., O. Fujiwara, and T. Takagi, "Effects of ferrite sheet attachment to portable telephone in reducing electromagnetic absorption in human head," IEEE International Symposium on Electromagnetic Compatability, Vol. 2, 822-825, Aug. 1999.
9. Gómez-Villanueva, R., H. Jardón-Aguilar, and R. L. y Miranda, "State of the art methods for low SAR antenna implementation," Proceedings of the Fourth European Conference on Antennas and Propagation, 1-4, Apr. 2010.
10. Stanley, M., Y. Huang, H. Wang, H. Zhou, Z. Tian, and Q. Xu, "A novel reconfigurable metal rim integrated open slot antenna for octa-band smartphone applications," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 7, 3352-3363, 2017. doi:10.1109/TAP.2017.2700084
11. Ban, Y.-L., Y.-F. Qiang, G. Wu, H. Wang, and K.-L. Wong, "Reconfigurable narrow-frame antenna for LTE/WWAN metal-rimmed smartphone applications," IET Microwaves, Antennas & Propagation, Vol. 10, No. 10, 1092-1100, 2016. doi:10.1049/iet-map.2015.0610
12. Zhang, L.-W., et al., "Parallel dual-loop antenna for WWAN/LTE metalrimmed smartphone," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 3, 1217-1226, 2018. doi:10.1109/TAP.2018.2796724
13. Garbacz, R. and R. Turpin, "A generalized expansion for radiated and scattered fields," IEEE Transactions on Antennas and Propagation, Vol. 19, No. 3, 348-358, 1971. doi:10.1109/TAP.1971.1139935
14. Chen, Y. and C.-F. Wang, Characteristic Modes: Theory and Applications in Antenna Engineering, John Wiley & Sons, 2015. doi:10.1002/9781119038900
16. Chae, S. H., S.-K. Oh, and S.-O. Park, "Analysis of mutual coupling, correlations, and TARC in WiBro MIMO array antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 6, 122-125, 2007. doi:10.1109/LAWP.2007.893109
17., "IEC/IEEE International Standard - Determining the peak spatial-average specific absorption rate (SAR) in the human body from wireless communications devices, 30 MHz to 6 GHz - Part 1: General requirements for using the finite-difference time-domain (FDTD) method for SAR calculations," IEC/IEEE 62704-1:2017, 1-86, Oct. 2017.
18., "IEEE recommended practice for determining the peak spatial-average specific absorption rate (SAR) in the human head from wireless communications devices: Measurement techniques," IEEE Std 1528-2013 (Revision of IEEE Std 1528-2003), 1-246, Sep. 2013.