A multiple-input-multiple-output (MIMO) antenna array with eight printed coplanar waveguide (CPW)-fed monopole antennas operating at 3.5 GHz (3.4-3.6 GHz) is presented. Each antenna is an Inverted-L (IL) monopole surrounded by a parasitic IL-shorted stripe and attains compact configuration. Both the IL-monopole and parasitic IL-shorted stripe contribute their fundamental resonant modes to operate in the desired frequency band. The neutralization line (NL) and ground middle slot are used for decoupling the antenna elements in the array. The measurement results for the prototype reasonably agree with electromagnetic simulations. Measured results for the proposed MIMO antenna array demonstrate that it has impedance bandwidth more than 200 MHz with (S11 < 6 dB), and with effective antenna decoupling mechanism the mutual coupling is better than 10 dB for the required band (3.4-3.6 GHz). In addition, envelope correlation coefficient (ECC) for the proposed MIMO antenna array is less than 0.2 for any two antennas to realize independent prorogation path for a channel. The average channel capacity of the proposed MIMO antenna array is approximately 35 to 38 bps/Hz for a reference signal to noise ratio (SNR) of 20 dB.
2. Sharawi, M. S., "Current misuses and future prospects for printed multiple-input, multiple-output antenna systems," IEEE Antennas and Propagation Magazine, Vol. 59, No. 2, 162-170, 2017.
3. Liao, W. J., C. Y. Hsieh, B. Y. Dai, and B. R. Hsiao, "Inverted-F/slot integrated dual-band fourantenna system for WLAN access points," IEEE Antennas Wireless Propag. Lett., Vol. 14, 847-850, 2015.
4. Guo, J., J. Fan, L. Sun, and B. Sun, "A four-antenna system with high isolation for mobile phones," IEEE Antennas and Wireless Propag. Lett., Vol. 12, 979-982, 2013.
5. Yang, L., H. Xu, J. Fang, and T. Li, "Four-element dual-band MIMO antenna system for mobile phones," Progress In Electromagnetics Research C, Vol. 60, 47-56, 2015.
6. 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. Opt. Technol. Lett., Vol. 58, 2046-2052, 2016.
7. Ramachandran, A., S. Valiyaveettil Pushpakaran, M. Pezholil, and V. Kesavath, "A four-port MIMO antenna using concentric square-ring patches loaded with CSRR for high isolation," IEEE Antennas and Wireless Propag. Lett., Vol. 15, 1196-1199, 2016.
8. Li, M. Y., Y. L. Ban, Z. Q. Xu, G. Wu, C. Y. D. Sim, K. Kang, and Z. F. Yu, "Eight-port orthogonally dual-polarized antenna array for 5G smartphone applications," IEEE Transactions on Antennas and Propagation, Vol. 64, No. 9, 3820-3830, 2016.
9. Choi, I. D., K. Lee, and J. Y. Lee, "A miniaturized 8-port integrated antenna with low farfield pattern correlation," IEEE International Symposium on Antennas and Propagation (APSURSI), 911-912, 2016.
10. Wong, K.-L., J.-Y. Lu, L.-Y. Chen, W.-Y. Li, and Y.-L. Ban, "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," Microw. Opt. Technol. Lett., Vol. 58, No. 1, 174-181, 2016.
11. Harrysson, F., J. Medbo, A. F. Molisch, A. J. Johansson, and F. Tufvesson, "Efficient experimental evaluation of a MIMO handset with user influence," IEEE Transactions on Wireless Communications, Vol. 9, No. 2, 853-863, 2010.
12. Mao, C. X., et al., "Compact coradiator UWB-MIMO antenna with dual polarization," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 9, 4474-4480, 2014.
13. Khan, M. S., et al., "Ultra-compact dual-polarised UWB MIMO antenna with meandered feeding lines," IET Microwaves, Antennas & Propagation, Vol. 11, No. 7, 997-1002, 2017.
14. Diallo, A., et al., "Enhanced two-antenna structures for universal mobile telecommunications system diversity terminals," IET Microwaves, Antennas & Propagation, Vol. 2, No. 1, 93-101, 2008.
15. Sharawi, M. S., et al., "A dual-element dual-band MIMO antenna system with enhanced isolation for mobile terminals," IEEE Antennas Wireless Propag. Lett., Vol. 11, 1006-1009, 2012.
16. Zhang, S., et al., "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, 2013.
17. Ando, A., et al., "Mean effective gain of mobile antennas in line-of-sight street microcells with low base station antennas," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 11, 3552-3565, 2008.
18. Ding, Y., et al., "A four-element antenna system for mobile phones," IEEE Antennas and Wireless Propag. Lett., Vol. 56, No. 11, 3552-3565, 2008.