In this paper, the effects of the locations of four dual-band antennas on a mobile terminal chassis are investigated in the vicinity of user's hand. To perform this study, a dual band four-port mobile terminal antenna for 5G is designed for operation in between 3.34 and 3.84 GHz (lower band, LB) and 5.15 and 6.52 GHz (upper band, UB), respectively. Due to the symmetry of the antenna elements (AEs), a right hand standard phantom is placed at a fixed position. Meanwhile, the antenna elements are placed at seven different locations across the chassis, with the best possible locations chosen based on the maximum efficiency in data mode. The influence of the human hand on the antenna performance is assessed based on two aspects: 1) in terms of matching (impedance mismatch (IM) and impedance bandwidth (IB)); and 2) in terms of efficiency (radiation efficiency (RE) and total efficiency (TE)). To validate its performance, the proposed antenna has been fabricated and measured. Results showed good agreement between simulations and measurements. Based on the results, a general design guideline for future 5G antennas operating in the sub-6 GHz bands considering user's hand effects can be outlined. The observed maximum variation for the proposed antenna with user's hand in terms of IM is -8 dB and -5 dB, respectively, and 57% and 37% in TE, respectively.
2. Rappaport, T. S., S. Sun, R. Mayzus, H. Zhao, Y. Azar, K. Wang, G. N. Wong, J. K. Schulz, M. Samimi, and F. Gutierrez, "Millimeter wave mobile communications for 5G cellular: It will work!," IEEE Access, Vol. 1, 335-349, 2013.
3. Chih-Lin, I., C. Rowell, S. Han, Z. Xu, G. Li, and Z. Pan, "Toward green and soft: A 5G perspective," IEEE Communications Magazine, Vol. 52, No. 2, 66-73, 2014.
4. 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, No. 3, 311-335, 1998.
5. Lau, B. K., "Multiple antenna terminals," MIMO: From Theory to Implementation, 267-298, 2011.
6. Al-Hadi, A. A. and R. Tian, "Impact of multiantenna real estate on diversity and MIMO performance in mobile terminals," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 1712-1715, 2013.
7. WRC-15 Press Release, "World radio communication conference allocates spectrum for future innovation,", [online], available: http://www.itu.int/net/pressoffice/pressreleases/2015/56, Nov. 27, 2015.
8. MT-2020 (5G) Promotion Group, "White paper on 5G concept,", [online], available: http://www.-imt-2020.org.cn/zh/documents/download/4, Feb. 2015.
9. Qualcomm, "Making the best use of licensed and unlicensed spectrum,", [online], available: https://www.qualcomm.com/media/documents/files/making-the-best-useof-unlicensed-spectrum-presentation.pdf, Sep. 2015.
10. SK Telecom, "SK telecom 5G white paper,", [online], available: http://www.sktelecom.com-/img/pds/press/SKT5G%20White%20PaperV1.0 Eng.pdf, Oct. 2014.
11. Ali, S. M., A. Mobasher, and P. Lusina, "User presence and antenna efficiency effects on MIMO link performance," 72nd Vehicular Technology Conference Fall (VTC 2010-Fall), 1-5, IEEE, 2010.
12. Goldsmith, A., S. A. Jafar, N. Jindal, and S. Vishwanath, "Capacity limits of MIMO channels," IEEE Journal on Selected Areas in Communications, Vol. 21, No. 5, 684-702, 2003.
13. Skafidas, E. and R. J. Evans, "Antenna effects on the capacity of MIMO communications systems in Rayleigh channels," 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, Vol. 1, 617-621, IEEE, 2004.
14. Piazza, D., N. J. Kirsch, A. Forenza, R. W. Heath, and K. R. Dandekar, "Design and evaluation of a reconfigurable antenna array for MIMO systems," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 3, 869-881, 2008.
15. Kildal, P. S. and K. Rosengren, "Correlation and capacity of MIMO systems and mutual coupling, radiation efficiency, and diversity gain of their antennas: Simulations and measurements in a reverberation chamber," IEEE Communications Magazine, Vol. 42, No. 12, 104-112, 2004.
16. Vasilev, I. and B. K. Lau, "On user effects in MIMO handset antennas designed using characteristic modes," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 758-761, 2016.
17. Ying, Z., "Antennas in cellular phones for mobile communications," Proceedings of the IEEE, Vol. 100, No. 7, 2286-2296, 2012.
18. Buskgaard, E., A. Tatomirescu, S. C. Del Barrio, O. Franek, and F. F. Pedersen, "User effect on the MIMO performance of a dual antenna LTE handset," 8th European Conference on Antennas and Propagation (EuCAP), 2006-2009, IEEE, 2014.
19. Li, C. H., E. Ofli, N. Chavannes, and N. Kuster, "Effects of hand phantom on mobile phone antenna performance," IEEE Transactions on Antennas and Propagation, Vol. 57, No. 9, 2763-2770, 2009.
20. Taga, T. and K. Tsunekawa, "Performance analysis of a built-in planar inverted F antenna for 800 MHz band portable radio units," IEEE Journal on Selected Areas in Communications, Vol. 5, No. 5, 921-929, 1987.
21. Sato, K., K. Matsumoto, K. Fujimoto, and K. Hirasawa, "Characteristics of a planar inverted-F antenna on a rectangular conducting body," Electronics and Communications in Japan (Part I: Communications), Vol. 72, No. 10, 43-51, 1989.
22. Taga, T., "Analysis of planar inverted-F antennas and antenna design for portable radio equipment," Analysis, Design, and Measurement of Small and Low Profile Antennas, 161-180, 1992.
23. Vainikainen, P., J. Ollikainen, O. Kivekas, and K. Kelander, "Resonator-based analysis of the combination of mobile handset antenna and chassis," IEEE Transactions on Antennas and Propagation, Vol. 50, No. 10, 1433-1444, 2002.
24. Ilvonen, J., O. Kivekas, J. Holopainen, R. Valkonen, K. Rasilainen, and P. Vainikainen, "Mobile terminal antenna performance with the user’s hand: Effect of antenna dimensioning and location," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 772-775, 2011.
25., , Schmid and Partner Engineering AG: 2010-2016 https://www.speag.com/products/emphantom/-hands/3to6ghz-hands-2/.