An 8-element/8-port antenna with four resonating dual-polarized slot radiator elements for sub-6 GHz 5G multiple-input multiple-output (MIMO) applications is proposed in this paper. The proposed MIMO design comprises four annular slot radiators with dual-polarized characteristic and has rectangular micro-strip line feeds. The designed elements operate in the frequency bands 2.73-3.12 GHz and 4.33-4.68 GHz providing an acceptable characteristic for dual-polarizations. The isolation improvement and reduction in mutual coupling factor are achieved by using split ring resonator (SRR) structures on the top layer along the slot radiator. The proposed design has a -10dB wide impedance bandwidth in both bands, considerable realized peak gain around 4 dBi, and better efficiencies around 80\% with ECC < 0.004 which has enhanced the performance of the MIMO array in terms of diversity. The antenna is fabricated, characterized, and it is shown that the measured results are in good agreement with the simulated ones. The proposed MIMO design has been analyzed for SAR functions and the radiation coverage in the vicinity of the user human head. The SAR values studied are found to be less than `2' which is quite desirable. All the features achieved in the proposed MIMO design suggest it to be suitable for 5G mobile terminal applications.
2. Li, Y., H. Zou, M. Wang, M. Peng, and G. Yang, "Eight-element MIMO antenna array for 5G/sub-6GHz indoor micro wireless access points," 2018 International Workshop on Antenna Technology (iWAT), 1-4, 2018.
3. Ahmad, A., "Design and performance analysis of six element MIMO antenna for wireless routers," 2016 19th International Multi-Topic Conference (INMIC), 1-4, 2016.
4. Ren, Z. and A. Zhao, "Dual-band MIMO antenna with compact self-decoupled antenna pairs for 5G mobile applications," IEEE Access, Vol. 7, 82 288-82 296, 2019.
5. Ojaroudi Parchin, N., H. J. Basherlou, Y. I. A. Al-Yasir, A. M. Abdulkhaleq, R. A. Abd-Alhameed, and P. S. Excell, "Eight-port MIMO antenna system for 2.6 GHz LTE cellular communications," Progress In Electromagnetics Research C, Vol. 99, 49-59, 2020.
6. Ojaroudi Parchin, N., H. J. Basherlou, and R. A. Abd-Alhameed, "Dual circularly polarized crescent-shaped slot antenna for 5G front-end systems," Progress In Electromagnetics Research Letters, Vol. 91, 41-48, 2020.
7. Masoodi, I. S., I. Ishteyaq, K. Muzaffar, and M. Idrees Magray, "Low cost substrate based compact antennas for 4G/5G side-edge panel smartphone applications," Progress In Electromagnetics Research Letters, Vol. 91, 145-152, 2020.
8. Sarkar, D. and K. V. Srivastava, "Four element dual-band sub-6GHz 5G MIMO antenna using SRR-loaded slot-loops," 2018 5th IEEE Uttar Pradesh Section International Conference on Electrical, Electronics and Computer Engineering (UPCON), 1-5, 2018.
9. Huang, B., W. Lin, J. Huang, J. Zhang, G. Zhang, and F. Wu, "A patch/dipole hybrid-mode antenna for sub-6 GHz communication," Sensors, Vol. 19, No. 6, 1358, 2019.
10. Li, Y., et al., "Multiband 10-antenna array for sub-6GHz MIMO applications in 5-G smartphones," IEEE Access, Vol. 6, 28 041-28 053, 2018.
11. Paul, P. M., K. Kandasamy, and M. S. Sharawi, "A multi-band U-strip and SRR loaded slot antenna with circular polarization characteristics," Advanced Electromagnetics, Vol. 9, No. 1, 41-48, 2020. [Online]. Available: 10.7716/aem.v9i1.1183.
12. Reshadatmand, M., H. R. Hassani, and S. M. A. Nezhad, "A compact wideband dielectric loaded H-plane sectoral ridged SIW horn antenna," Advanced Electromagnetics, Vol. 9, No. 2, 1-6, 2020. [Online]. Available: 10.7716/aem.v9i3.1268.
13. Deng, J., J. 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. Wong, K., C. Tsai, and J. Lu, "Two asymmetrically mirrored gap-coupled loop antennas as a compact building block for eight-antenna MIMO array in the future smartphone," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 4, 1765-1778, 2017.
15. Ling, X. and R. Li, "A novel dual-band MIMO antenna array with low mutual coupling for portable wireless devices," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 1039-1042, 2011.
16. Wang, Y. and Z. Du, "A wideband printed dual-antenna with a protruded ground for mobile terminals," 2014 IEEE Antennas and Propagation Society International Symposium (APSURSI), 1133-1134, 2014.
17. 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," Microwave and Optical Technology Letters, Vol. 58, No. 1, 174-181, 2016. [Online]. Available: https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.29527.
18. Ishteyaq, I., I. S. Masoodi, and K.Muzaffar, "Wideband printed quasi-yagi MIMO antenna for millimeter wave applications," 2019 IEEE Indian Conference on Antennas and Propagation (InCAP), 1-4, Dec. 2019. [Online]. Available: 1109/InCAP47789.2019.9134583.
19. Nazeri, A., A. Abdolali, and M. Mehdi, "An extremely safe low-SAR antenna with study of its electromagnetic biological effects on human head," Wireless Personal Communications, Vol. 109, No. 2, 1449-1462, 2019. [Online]. Available: 1007/s11277-019-06621-6.
20. Fields, R. F. E., "Ieee standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, kHz to 300 GHz," IEEE Standard, Vol. C95.1, 2005.
21. Ojaroudi Parchin, N., Y. I. Al-Yasir, H. J. Basherlou, A. M. Abdulkhaleq, M. Sajedin, R. A. Abd-Alhameed, and J. M. Noras, "Modified PIFA array design with improved bandwidth and isolation for 5G mobile handsets," 2019 IEEE 2nd 5G World Forum (5GWF), 199-203, IEEE, 2019. [Online]. Available: 1109/5GWF.2019.8911725.
22. Ojaroudi Parchin, N., H. Jahanbakhsh Basherlou, Y. I. Al-Yasir, A. M. Abdulkhaleq, M. Patwary, and R. A. Abd-Alhameed, "A new CPW-fed diversity antenna for MIMO 5G smartphones," Electronics, Vol. 9, No. 2, 261, 2020. [Online]. Available: 3390/electronics9020261.
23. Ojaroudi Parchin, N., H. Jahanbakhsh Basherlou, Y. I. Al-Yasir, A. Ullah, R. A. Abd-Alhameed, and J. M. Noras, "Multi-band MIMO antenna design with user-impact investigation for 4G and 5G mobile terminals," Sensors, Vol. 19, No. 3, 456, 2019. [Online]. Available: 3390/s19030456.
24. Ojaroudi Parchin, N., H. Jahanbakhsh Basherlou, M. Alibakhshikenari, Y. Ojaroudi Parchin, Y. I. Al-Yasir, R. A. Abd-Alhameed, and E. Limiti, "Mobile-phone antenna array with diamond-ring slot elements for 5G massive MIMO systems," Electronics, Vol. 8, No. 5, 521, 2019. [Online]. Available: 3390/electronics8050521.
25. Ishteyaq, I., I. S. Masoodi, and K. Muzaffar, "A compact double-band planar printed slot antenna for sub-6 GHz 5G wireless applications," International Journal of Microwave and Wireless Technologies, 1-9, 2020. [Online]. Available: 1017/S1759078720001269.
26. Azeez, H. I., H.-C. Yang, and W.-S. Chen, "Wearable triband E-shaped dipole antenna with low SAR for IoT applications," Electronics, Vol. 8, No. 6, 665, 2019. [Online]. Available: 3390/electronics8060665.
27. Ren, Z., A. Zhao, and S.Wu, "MIMO antenna with compact decoupled antenna pairs for 5G mobile terminals," IEEE Antennas and Wireless Propagation Letters, Vol. 18, No. 7, 1367-1371, 2019.
28. Ojaroudi Parchin, N., Y. I. A. Al-Yasir, A. H. Ali, I. Elfergani, J. M. Noras, J. Rodriguez, and R. A. Abd-Alhameed, "Eight-element dual-polarized MIMO slot antenna system for 5G smartphone applications," IEEE Access, Vol. 7, 15 612-15 622, 2019.
29. Elshirkasi, A. M., A. Abdullah Al-Hadi, M. F. Mansor, R. Khan, and P. J. Soh, "Envelope correlation coefficient of a two-port MIMO terminal antenna under uniform and gaussian angular power spectrum with user’s hand effect," Progress In Electromagnetics Research C, Vol. 92, 123-136, 2019.
30. Anguera, J., A. And´ujar, M.-C. Huynh, C. Orlenius, C. Picher, and C. Puente, "Advances in antenna technology for wireless handheld devices," International Journal of Antennas and Propagation, Vol. 2013, 2013.
31. Sun, L., H. Feng, Y. Li, and Z. Zhang, "Compact 5G MIMO mobile phone antennas with tightly arranged orthogonal-mode pairs," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 11, 6364-6369, 2018.
32. Jiang, Z. H., D. E. Brocker, P. E. Sieber, and D. H. Werner, "A compact, low-profile metasurfaceenabled antenna for wearable medical body-area network devices," IEEE Transactions on Antennas and Propagation, Vol. 62, No. 8, 4021-4030, 2014.
33. Islam, M., M. Alam, N. Misran, M. Ismail, and B. Yatim, "Development of high gain multiband antenna with centre-offset copper strip-based periodic structure," Microwave and Optical Technology Letters, Vol. 57, No. 7, 1608-1614, 2015.
34. Ojaroudi Parchin, N., Y. I. Al-Yasir, J. M. Noras, and R. A. Abd-Alhameed, "Dual-polarized MIMO antenna array design using miniaturized self-complementary structures for 5G smartphone applications," 2019 13th European Conference on Antennas and Propagation (EuCAP), 1-4, IEEE, 2019.
35. Li, M., Z. Xu, Y. Ban, Q. Yang, and Q. Zhou, "Eight-port dual-polarized MIMO antenna for 5G smartphone applications," 2016 IEEE 5th Asia-Pacific Conference on Antennas and Propagation (APCAP), 195-196, 2016.