This paper proposes a two-element LTE MIMO handset antenna with physically different main and diversity antennas. The performance of the design is studied theoretically and experimentally. The investigated design utilizes physically different main and diversity antennas to improve especially the low-band MIMO performance. A Combined Parasitic-coupled, Aperture-Matched (CPAM) antenna is used as the main antenna, and the diversity antenna is a simple Capacitive Coupling Element (CCE) design. The antenna covers the LTE bands from 698-960MHz and 1710-2690MHz with fixed matching circuits suitable for low-band (LB) Carrier Aggregation (CA). Measured total efficiency of the antennas is from -3 to -6 dB and -2 to -5 dB at the low and high bands, respectively. In the MIMO case, envelope correlation (ECC) and multiplexing efficiency are studied also from measurements.
2. Bassam, S. A., W. Chen, M. Helaoui, and F. M. Ghannouchi, "Transmitter architecture for CA: Carrier aggregation in LTE-Advanced systems," IEEE Microw. Mag., Vol. 14, No. 5, 78-86, Jul./Aug. 2013.
3. Valkonen, R., A. Lehtovuori, and C. Icheln, "Dual-feed, single-CCE antenna facilitating interband carrier aggregation in LTE-A handsets," 2013 7th European Conference on Antennas and Propagation (EuCAP), 3954-3958, Gothenburg, Sweden, Apr. 2013.
4. Yoon, C., S.-G. Hwang, G.-C. Lee, W.-S. Kim, H.-C. Lee, C.-H. Lee, and H.-D. Park, "A frequencyselecting technique for mobile handset antennas based on capacitance switching," Progress In Electromagnetics Research, Vol. 138, 99-113, 2013.
5. Ali, S. M. and K. Payandejoo, "Tunable antenna techniques for compact handset applications," IET Microw. Antennas Propag., Vol. 8, No. 6, 401-408, Apr. 2014.
6. Caporal del Barrio, S., A. Morris, and G. F. Pedersen, "Addressing carrier aggregation with narrowband tunable antennas," 2016 10th European Conference on Antennas and Propagation (EuCAP), 1-5, Davos, Switzerland, Apr. 2016.
7. Wong, K.-L., Y.-C. Chen, and W.-Y. Li, "Four LTE low-band smartphone antennas and their MIMO performance with user’s hand presence," Microw. Optical Technol. Lett., Vol. 58, No. 9, 2046-2052, Sep. 2016.
8. 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 Microw. Antennas Propag., Vol. 10, No. 10, 1092-1100, Jul. 2016.
9. Li, H., Z. T. Miers, and B. K. Lau, "Design of orthogonal MIMO handset antennas based on characteristic mode manipulation at frequency bands below 1GHz," IEEE Trans. Antennas Propag., Vol. 62, No. 5, 2756-2766, May 2014.
10. Wi, H., B. Kim, W. Jung, and B. Lee, "Multiband handset antenna analysis including LTE band MIMO service," Progress In Electromagnetics Research, Vol. 138, 661-673, 2013.
11. Villanen, J., J. Ollikainen, O. Kivekas, and P. Vainikainen, "Coupling element based mobile terminal antenna structures," IEEE Trans. Antennas Propag., Vol. 54, No. 7, 2142-2153, Jul. 2006.
12. Vainikainen, P., J. Ollikainen, O. Kivekas, and I. Kelander, "Resonator-based analysis of the combination of mobile handset antenna and chassis," IEEE Trans. Antennas Propag., Vol. 50, No. 10, 1433-1444, Oct. 2002.
13. Rasilainen, K., A. Lehtovuori, and V. Viikari, "LTE handset antenna with closely-located radiators, low-band MIMO, and high efficiency," 2017 11th European Conference on Antennas and Propagation (EuCAP), 3074-3078, Paris, France, Mar. 2017.
14., , CST Microwave Studio, an FDTD/FIT based electromagnetic simulator, version 2013, CST AG, Darmstadt, Germany, [Online], Available: http://www.cst.com (Cited Jun. 8, 2017).
15., , Optenni Lab, matching circuit generation and antenna analysis software, ver. 3.3, Optenni Ltd., Espoo, Finland, [Online], Available: http://www.optenni.com (Cited Jun. 8, 2017).
16. Kildal, P.-S., Foundations of Antenna Engineering: A Unified Approach for Line-of-Sight and Multipath, Kildal, 2015.
17. Ilvonen, J., R. Valkonen, J. Holopainen, and V. Viikari, "Design strategy for 4G handset antenna and a multiband hybrid antenna," IEEE Trans. Antennas Propag., Vol. 62, No. 4, 1918-1927, Apr. 2014.
18. Lehtovuori, A., J. Ilvonen, K. Rasilainen, and V. Viikari, "Single-element handset antenna design for modern smartphones: An industrial approach," 2017 11th European Conference on Antennas and Propagation (EuCAP), 2960-2963, Paris, France, Mar. 2017.
19. Ilvonen, J., J. Holopainen, K. Rasilainen, A. Lehtovuori, and V. Viikari, "Suitable multiantenna placement in mobile handsets based on electromagnetic isolation," 2016 10th European Conference on Antennas and Propagation (EuCAP), 1-4, Davos, Switzerland, Apr. 2016.
20. Wong, K.-L., T.-W. Kang, and M.-F. Tu, "Internal mobile phone antenna array for LTE/WWAN and LTE MIMO operations," Microw. Optical Technol. Lett., Vol. 53, No. 7, 1569-1573, Jul. 2011.
21. Cihangir, A., F. Ferrero, G. Jacquemod, P. Brachat, and C. Luxey, "Neutralized coupling elemets for MIMO operation in 4G mobile terminals," IEEE Antennas Wireless Propag. Lett., Vol. 13, 141-144, 2014.
22. Zhang, S., K. Zhao, Z. Ying, and S. He, "Adaptive quad-element multi-wideband antenna array for user-effective LTE MIMO mobile terminals," IEEE Trans. Antennas Propag., Vol. 61, No. 8, 4275-4283, Aug. 2013.
23. Li, K., Y. Shi, and C.-H. Liang, "Quad-element multi-band antenna array in the smart mobile phone for LTE MIMO operations," Microw. Opt. Technol. Lett., Vol. 58, No. 11, 2619-2626, Nov. 2016.
24. Ilvonen, J., R. Valkonen, J. Holopainen, and V. Viikari, "Multiband frequency reconfigurable 4G handset antenna with MIMO capability," Progress In Electromagnetics Research, Vol. 148, 233-243, 2014.
25. Vaughan, R. G. and J. Bach Andersen, "Antenna diversity in mobile communications," IEEE Trans. Veh. Commun., Vol. VT-36, No. 4, 149-172, Nov. 1987.
26. Tian, R., B. K. Lau, and Z. Ying, "Multiplexing efficiency of MIMO antennas," IEEE Antennas Wireless Propag. Lett., Vol. 10, 183-186, 2011.
27. Blanch, S., J. Romeu, and I. Corbella, "Exact representation of antenna system diversity performance from input parameter description," Electron. Lett., Vol. 39, No. 9, 705-707, May 2003.
28. Shoaib, S., I. Shoaib, X. Chen, and C. G. Parini, "MIMO antennas for next generation mobile terminals," 2016 10th European Conference on Antennas and Propagation (EuCAP), 1-4, Davos, Switzerland, Apr. 2016.
29. Chamok, N. H., M. H. Yilmaz, H. Arslan, and M. Ali, "High-gain pattern reconfigurable MIMO antenna array for wireless handheld terminals," IEEE Trans. Antennas Propag., Vol. 64, No. 10, 4306-4315, Oct. 2016.