In this paper, a dual-band modified multiple-input-multiple-output (MIMO) antenna with high isolation is presented and discussed. The proposed compact structure (35 × 25 mm2) consists of two monopole elements and defected ground planes to obtain high impedance bandwidth. Two elliptical-shaped patches are placed orthogonal to each other to obtain high isolation, and a neutralization slit is integrated into the ground plane of each element to further improve the isolation between the elements. The measurement results of the proposed structure show satisfactory agreement with the simulation results. The measured bandwidths are 47.05% (2.6-4.2 GHz) and 64.72% (5.11-10 GHz) at S11 ≤ -10 dB which covers bandwidth requirements of WiMAX (3.4-3.6 GHz, 5.25-5.85 GHz), sub 6 GHz 5G band (3.4-3.8 GHz), WLAN (5.15-5.35 GHz, 5.725-5.825 GHz), and X band satellite communication systems (7.25–8.39 GHz). The designed antenna offers a peak gain of about 9.0 dBi and radiation efficiency of about 92%. The measured minimum isolation is greater than 27.3 dB across the dual band with a maximum value of 73.4 dB. The envelope correlation coefficient (ECC) is below 0.0035, channel capacity loss less than 0.37 bits/s/Hz, and peak diversity gain about 10 dBi.
2. Ding, K., C. Gao, D. Qu, and Q. Yin, "Compact broadband MIMO antenna with parasitic strip," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2349-2353, 2017.
3. Xia, X.-X., Q.-X. Chu, and J.-F. Li, "Design of a compact wideband MIMO antenna for mobile terminals," Progress In Electromagnetics Research C, Vol. 41, 163-174, 2013.
4. Sharawi, M. S., A. B. Numan, M. U. Khan, and D. N. Aloi, "A CSRR loaded MIMO antenna system for ISM band operation," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 8, 4265-4274, 2013.
5. Debdeep, S. and V. K. Srivastava, "A compact four-element MIMO/diversity antenna with enhanced bandwidth," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2469-2472, 2017.
6. Ming, Y. and J. Zhou, "A compact pattern diversity MIMO antenna with enhanced bandwidth and high-isolation characteristics for WLAN/5G/WiFi applications," Microwave and Optical Technology Letters, 1-12, 2020.
7. Rifaqat, H., A. Ghalib, and M. S. Sharawi, "Annular slot-based miniaturized frequency-agile MIMO antenna system," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2489-2492, 2017.
8. Shi, H., X. Zhang, J. Li, P. Jia, J. Chen, and A. Zhang, "3.6-GHz eight-antenna MIMO array for mobile terminal applications," AEÜ --- Int. J. Electron. Commun., Vol. 95, 342-348, 2018.
9. Zhang, S. and G. Pedersen, "Mutual coupling reduction for UWB MIMO antennas with a wideband neutralization line," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 166-175, 2015.
10. Wang, Y. and Z. Dun, "A wideband printed dual-antenna system with a novel neutralization line for mobile terminals," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 1428-1431, 2013.
11. Rezvani, M. H. and Z. Yashar, "A dual-band multiple-input multiple-output microstrip antenna with metamaterial structure for LTE and WLAN applications," AEÜ --- Int. J. Electron. Commun., Vol. 93, 277-282, 2018.
12. Sharawi, M. S., A. B. Numan, M. U. Khan, and D. N. Aloi, "A dual-element dual-band MIMO antenna system with enhanced isolation for mobile terminals," IEEE Antennas and Wireless Propagation Letters, Vol. 11, 1006-1009, 2012.
13. Deng, J. Y., J. Y. Li, L. Zhao, and L. Guo, "A dual-band inverted-F MIMO antenna with enhanced isolation for WLAN applications," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2270-2273, 2017.
14. Leeladhar, M., M. V. Kartikeyan, and R. K. Panigrahi, "Offset planar MIMO antenna for omnidirectional radiation patterns," International Journal of RF and Microwave Computer Aided Engineering, Vol. 28, No. 6, e21274, 2018.
15. Amer, T. A., "Novel sun ower MIMO fractal antenna with low mutual coupling and dual wide operating bands," International Journal of Microwave and Wireless Technologies, 1-9, doi.org/10.1017/S1759078719001375.
16. Kumar, A., Q. A. Ansari, B. K. Kanaujia, and J. Kishor, "A novel ITI-shaped isolation structure placed between two-port CPW-fed dual-band MIMO antenna for high isolation," AEÜ --- Int. J. Electron. Commun., Vol. 104, 35-43, 2019.
17. Deng, J. Y., Z. J. Wang, J. Y. Li, and X. G. Li, "A dual-band MIMO antenna decoupled by a meandering line resonator for WLAN applications," Microwave and Optical Technology Letters, Vol. 60, No. 3, 759-765, 2018.
18. Leeladhar, M., R. K. Panigrahi, and M. V. Kartikeyan, "A 2 × 2 dual-band MIMO antenna with polarization diversity for wireless applications," Progress In Electromagnetics Research C, Vol. 61, 91-103, 2016.
19. Sarkar, D. and K. V. Srivastava, "Compact four-element SRR-loaded dual-band MIMO antenna for WLAN/WiMAX/WiFi/4G-LTE and 5G applications," Electronics Letters, Vol. 53, 1623-1624, 2017.
20. Luo, C.-M., J.-S. Hong, and M. Amin, "Mutual coupling reduction for dual-band MIMO antenna with simple structure," Radioengineering, Vol. 26, 51-56, 2017.
21. Jiang, W., Y. Cui, B. Liu, and W. Hu, "A dual-band MIMO antenna with enhanced isolation for 5G smartphone applications," IEEE Access, Vol. 7, 112554-112563, 2019.
22. Liu, Y., L. Yang, Y. Liu, J. Ren, J. Wang, and X. Li, "Dual-band planar MIMO antenna for WLAN application," Microwave and Optical Technology Letters, Vol. 57, No. 10, 2257-2262, 2015.
23. Desde, I., G. Bozdag, and A. Kustepeli, "Multi-band CPW-fed MIMO antenna for Bluetooth WLAN and WiMAX applications," Microwave and Optical Technology Letters, Vol. 58, No. 9, 2182-2186, 2016.
24. Ko, S. C. K. and R. D. Murch, "Compact integrated diversity antenna for wireless communications," IEEE Transactions on Antennas and Propagation, Vol. 49, 954-960, 2001.
25. Ramkrishnan, B. K. and G. N. Mulay, "Design of compact multiband pattern diversity antenna for WiMax, LTE and WLAN applications," Microsyst Technol., Vol. 23, 1949-1960, 2017.
26. Mabrouk, I. B., L. Talbi, M. Nedil, and K. Hettak, "MIMO-UWB channel characterization within an underground mine gallery," IEEE Transactions on Antennas and Propagation, Vol. 60, No. 10, 4866-4874, 2012.
27. Ramachandran, A., S. Mathew, V. P. Viswanathan, M. Pezholil, and V. Kesavath, "Diversity-based four-port multiple input multiple output antenna loaded with interdigital structure for high isolation," IET Microwaves Antennas Propag., Vol. 10, No. 15, 1633-42, 2016.
28. Chandel, R., A. K. Gautam, and K. Rambabu, "Tapered fed compact UWB MIMO-diversity antenna with dual band-notched characteristics," IEEE Transactions on Antennas and Propagation, Vol. 66, 1677-1684, 2018.
29. Kumar, A., A. Q. Ansari, B. K. Kanaujia, and J. Kishor, "High isolation compact four-port MIMO antenna loaded with CSRR for multiband applications," Frequenz, Vol. 72, 415-27, 2018.
30. Kumar, A., S. Kumar, Sinha, R. Sinha, and A. Choubey, "Dual circular slot ring triple-band MIMO antenna for 5G applications," Frequenz, Vol. 75, 91-100, 2021.