In this paper, a design of dual band 10 × 10 antenna array for 5G Massive Multi-Input Multi-Output (MIMO) applications in the mobile phone is presented. The designed array is proposed to cover the sub-6 GHz bands (LTE bands 42/43 and LTE band 46). To realize MIMO operation in these three LTE bands, ten ring loop antenna elements are integrated into a limited space cell phone circuit board. Due to the implementation of spatial diversity techniques on the antenna elements, better isolation can be achieved. The proposed array was simulated, fabricated and measured. It achieved good MIMO performances, such as ergodic channel capacities higher than 27.1 bps/Hz and 57.6 bps/Hz for LTE bands 42/43 and LTE band 46 respectively. Also, the achieved Envelope Correlation Coefficient (ECC) is lower than 0.006. Moreover, it exhibited good isolation below -26 dB. The effects of user's hand phantom on the proposed array performance are also studied in two scenarios: Single Hand Mode (SHM) and Dual Hands Mode (DHM). The simulated results indicate that the proposed MIMO array can still achieve good MIMO performances in the presence of DHM and SHM. The Specific Absorption Rate (SAR) are also presented.
2. Tang, W., S. Kang, J. Zhao, Y. Zhang, X. Zhang, and Z. Zhang, "Design of MIMO-PDMA in 5G mobile communication system," IET Commun., Vol. 14, No. 1, 76-83, 2020, doi: 10.1049/iet-com.2018.5837.
3. Dadhich, A., M. Sharma, and J. K. Deegwal, "Design and investigation of wideband and multiband microstrip patch antenna for Bluetooth, TD-LTE, ITU and X-band applications," Int. Conf. Emerg. Trends Eng. Innov. Technol. Manag. (ICET EITM-2017), Vol. 2, 409-412, ISBN 978-93-86724-30-4, 2017.
4. Zou, H., Y. Li, C. Sim, and G. Yang, "Design of 8 × 8 dual-band MIMO antenna array for 5G smartphone applications," Int. J. RF Microw. Comput. Eng., Vol. 58, No. 1, 174-181, 2018, doi: 10.1002/mmce.21420.
5. Agiwal, M., A. Roy, and N. Saxena, "Next generation 5G wireless networks?: A comprehensive survey," IEEE Communications Surveys & Tutorials, Vol. 18, No. 3, 1617-1655, 2016.
6. Singh, A. and C. E. Saavedra, "Wide-bandwidth inverted-F stub fed hybrid loop antenna for 5G sub-6 GHz massive MIMO enabled handsets," IET Microwaves, Antennas Propag., Vol. 14, No. 7, 677-683, 2020, doi: 10.1049/iet-map.2019.0980.
7. Parchin, N. O., H. J. Basherlou, I. A. Yasir Al-Yasir, M. Sajedin, J. Rodriguez, and R. A. Abd-Alhameed, "Multi-mode smartphone antenna array for 5G massive MIMO applications," 14th Eur. Conf. Antennas Propagation, EuCAP 2020, 4-7, 2020, doi: 10.23919/EuCAP48036.2020.9135754.
8. Al-Dulaimi, A., S. Al-Rubaye, Q. Ni, and E. Sousa, "5G communications race: Pursuit of more capacity triggers LTE in unlicensed band," IEEE Vehicular Technology Magazine, Vol. 10, No. 1, 43-51, 2015, doi: 10.1109/MVT.2014.2380631.
9. Serghiou, D., M. Khalily, V. Singh, A. Araghi, and R. Tafazolli, "Sub-6 GHz dual-band 8 × 8 MIMO antenna for 5G smartphones," IEEE Antennas Wirel. Propag. Lett., Vol. 1225, 2020, doi: 10.1109/lawp.2020.3008962.
10. Rao, L.-Y. and C.-J. Tsai, "8-loop antenna array in the 5 inches size smartphone for 5G communication the 3.4 GHz-3.6 GHz band MIMO operation," 2018 Progress In Electromagnetics Research Symposium (PIERS - Toyama), 1995-1999, Toyama, Japan, Aug. 1-4, 2018.
11. Ren, Z., A. Zhao, and S. Wu, "MIMO antenna with compact decoupled antenna pairs for 5G mobile terminals," IEEE Antennas Wirel. Propag. Lett., Vol. 18, No. 7, 1367-1371, 2019, doi: 10.1109/LAWP.2019.2916738.
12. Li, Y., C. Y. D. Sim, Y. Luo, and G. Yang, "12-port 5G massive MIMO antenna array in sub-6 GHz mobile handset for LTE bands 42/43/46 applications," IEEE Access, Vol. 6, 344-354, 2017, doi: 10.1109/ACCESS.2017.2763161.
13. Sim, C. Y. D., H. Y. Liu, and C. J. Huang, "Wideband MIMO antenna array design for future mobile devices operating in the 5G NR frequency bands n77/n78/n79 and LTE band 46," IEEE Antennas Wirel. Propag. Lett., Vol. 19, No. 1, 74-78, 2020, doi: 10.1109/LAWP.2019.2953334.
14. Zhao, A. and Z. Ren, "Size reduction of self-isolated MIMO antenna system for 5G mobile phone applications," IEEE Antennas Wirel. Propag. Lett., Vol. 18, No. 1, 152-156, 2019, doi: 10.1109/LAWP.2018.2883428.
15. Li, Y., C. Y. D. Sim, Y. Luo, and G. Yang, "Metal-frame-integrated eight-element multiple-input multiple-output antenna array in the long term evolution bands 41/42/43 for fifth generation smartphones," Int. J. RF Microw. Comput. Eng., Vol. 29, No. 1, 2019, doi: 10.1002/mmce.21495.
16. Li, Y., C. Y. D. Sim, Y. Luo, and G. Yang, "Multiband 10-antenna array for sub-6 GHz MIMO applications in 5-G smartphones," IEEE Access, Vol. 6, 28041-28053, 2018, doi: 10.1109/ACCESS.2018.2838337.
17. Li, Y. and G. Yang, "Dual-mode and triple-band 10-antenna handset array and its multiple-input multiple-output performance evaluation in 5G," Int. J. RF Microw. Comput. Eng., Vol. 29, No. 2, 1-15, 2019, doi: 10.1002/mmce.21538.
18. Li, Y., C. Y. D. Sim, Y. Luo, and G. Yang, "High-isolation 3.5 GHz eight-antenna MIMO array using balanced open-slot antenna element for 5G smartphones," IEEE Trans. Antennas Propag., Vol. 67, No. 6, 3820-3830, 2019, doi: 10.1109/TAP.2019.2902751.
19. Alber, J. and R. Niedermeier, "On multidimensional curves with hilbert property," Theory Comput. Syst., Vol. 33, No. 4, 295-312, 2000, doi: 10.1007/s002240010003.
20. Sharawi, M. S., "Printed multi-band MIMO antenna systems and their performance metrics [wireless corner]," IEEE Antennas Propag. Mag., Vol. 55, No. 5, 218-232, 2013, doi: 10.1109/MAP.2013.6735522.
21. Tian, R., B. K. Lau, and Z. Ying, "Multiplexing efficiency of MIMO antennas," IEEE Antennas Wirel. Propag. Lett., Vol. 10, 183-186, Sep. 2011, doi: 10.1109/LAWP.2011.2125773.
22. Chen, Q., et al., "Single ring slot-based antennas for metal-rimmed 4G/5G smartphones," IEEE Trans. Antennas Propag., Vol. 67, No. 3, 1476-1487, 2019, doi: 10.1109/TAP.2018.2883686.
23. 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,", 2017.
24. Perhirin, S. and Y. Auffret, "8-antenna and 16-antenna arrays using the quad-antenna linear array as a building block for the 3.5-GHz LTE MIMO operation in the smartphone," Microwave and Optical Technology Letters, Vol. 58, No. 1, 2562-2568, 2016, doi: 10.1002/mop.