volume | PIER Journals

Abstract

To satisfy the demand for 5G communication to smartphone terminal antennas in element quantity and isolation, an eight-element broadband MIMO antenna system with high isolation is proposed in this paper. The antenna element consists of an L-shaped feed line and a rectangular slot with an open slot. Meanwhile, a stepped impedance tuning structure was integrated within the rectangular slot to optimize broadband impedance matching and expand the operational bandwidth. In addition, a Chinese character ``工''-shaped defective ground structure has been innovatively designed to reduce surface wave coupling on the ground plane, achieving an isolation level of over -15 dB. Furthermore, eight antenna elements and six defective ground structures are symmetrically distributed along the long edges of the substrate, with coupling feeding performed through the L-shaped feed lines. The proposed antenna system ultimately achieves an operating bandwidth of 3.4-6.5 GHz below -10 dB, with a total efficiency greater than 90% and an envelope correlation coefficient of less than 0.016. The stability of the system in overlay screen mode, as well as in single-handed and dual-handed smartphone operation modes, is also demonstrated to showcase its practical applications.

1. Sghaier, Nizar, Lassaad Latrach, and Ali Gharsallah, "Design of a dual-polarized UWB 5G NR antenna," Wireless Personal Communications, Vol. 123, No. 2, 1293-1310, 2022. Google Scholar

2. Jaglan, Naveen, Samir Dev Gupta, Binod Kumar Kanaujia, and Mohammad S. Sharawi, "10 element sub-6-GHz multi-band double-T based MIMO antenna system for 5G smartphones," IEEE Access, Vol. 9, 118662-118672, 2021. Google Scholar

3. "3GPP specification series: 38 series," 3GPP TS 38.101-1 v15.0.0, 2017.

4. Yang, Bixia, Yunxue Xu, Jiahao Tong, Yuhao Zhang, Yuwen Feng, and Yafei Hu, "Tri-port antenna with shared radiator and self-decoupling characteristic for 5G smartphone application," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 6, 4836-4841, 2022. Google Scholar

5. Hu, Wei, Zhan Chen, Long Qian, Lehu Wen, Qi Luo, Rui Xu, Wen Jiang, and Steven Gao, "Wideband back-cover antenna design using dual characteristic modes with high isolation for 5G MIMO smartphone," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 7, 5254-5265, 2022. Google Scholar

6. Chang, Le, Yafang Yu, Kunpeng Wei, and Hanyang Wang, "Polarization-orthogonal co-frequency dual antenna pair suitable for 5G MIMO smartphone with metallic bezels," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 8, 5212-5220, 2019. Google Scholar

7. Li, Yixin, Chow-Yen-Desmond Sim, Yong Luo, and Guangli Yang, "High-isolation 3.5 GHz eight-antenna MIMO array using balanced open-slot antenna element for 5G smartphones," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 6, 3820-3830, 2019. Google Scholar

8. Sun, Libin, Yue Li, Zhijun Zhang, and Hanyang Wang, "Self-decoupled MIMO antenna pair with shared radiator for 5G smartphones," IEEE Transactions on Antennas and Propagation, Vol. 68, No. 5, 3423-3432, 2020. Google Scholar

9. Ren, Aidi, Ying Liu, Hong-Wei Yu, Yongtao Jia, Chow-Yen-Desmond Sim, and Yunxue Xu, "A high-isolation building block using stable current nulls for 5G smartphone applications," IEEE Access, Vol. 7, 170419-170429, 2019. Google Scholar

10. Xu, Hang, Steven Shichang Gao, Hai Zhou, Hanyang Wang, and Yujian Cheng, "A highly integrated MIMO antenna unit: Differential/common mode design," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 11, 6724-6734, 2019. Google Scholar

11. Zhao, Anping and Zhouyou Ren, "Size reduction of self-isolated MIMO antenna system for 5G mobile phone applications," IEEE Antennas and Wireless Propagation Letters, Vol. 18, No. 1, 152-156, 2019. Google Scholar

12. Deng, Changjiang, Di Liu, and Xin Lv, "Tightly arranged four-element MIMO antennas for 5G mobile terminals," IEEE Transactions on Antennas and Propagation, Vol. 67, No. 10, 6353-6361, 2019. Google Scholar

13. Xu, Hang, Hai Zhou, Steven Gao, Hanyang Wang, and Yujian Cheng, "Multimode decoupling technique with independent tuning characteristic for mobile terminals," IEEE Transactions on Antennas and Propagation, Vol. 65, No. 12, 6739-6751, 2017. Google Scholar

14. Alja’Afreh, Saqer S., Bayan Altarawneh, Mallak H. Alshamaileh, E’qab R. Almajali, Rifaqat Hussain, Mohammad S. Sharawi, Lei Xing, and Qian Xu, "Ten antenna array using a small footprint capacitive-coupled-shorted loop antenna for 3.5 GHz 5G smartphone applications," IEEE Access, Vol. 9, 33796-33810, 2021. Google Scholar

15. Zhao, Xing, Swee Ping Yeo, and Ling Chuen Ong, "Decoupling of inverted-F antennas with high-order modes of ground plane for 5G mobile MIMO platform," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 9, 4485-4495, 2018. Google Scholar

16. Barani, Imee Ristika Rahmi, Kin-Lu Wong, Yu-Xuan Zhang, and Wei-Yu Li, "Low-profile wideband conjoined open-slot antennas fed by grounded coplanar waveguides for 4 × 4 5G MIMO operation," IEEE Transactions on Antennas and Propagation, Vol. 68, No. 4, 2646-2657, 2020. Google Scholar

17. Hu, Wei, Qiaosong Li, Hao Wu, Zhan Chen, Lehu Wen, Wen Jiang, and Steven Gao, "Dual-band antenna pair with high isolation using multiple orthogonal modes for 5G smartphones," IEEE Transactions on Antennas and Propagation, Vol. 71, No. 2, 1949-1954, 2023. Google Scholar

18. Yuan, Xiao-Ting, Wei He, Kai-Dong Hong, Chong-Zhi Han, Zhe Chen, and Tao Yuan, "Ultra-wideband MIMO antenna system with high element-isolation for 5G smartphone application," IEEE Access, Vol. 8, 56281-56289, 2020. Google Scholar

19. Hei, Yong Qiang, Jia Geng He, and Wen Tao Li, "Wideband decoupled 8-element MIMO antenna for 5G mobile terminal applications," IEEE Antennas and Wireless Propagation Letters, Vol. 20, No. 8, 1448-1452, 2021. Google Scholar

20. Ahn, Junhyuk, Youngno Youn, Bumhyun Kim, Jeonghyo Lee, Nakchung Choi, Yoonjae Lee, Gyusub Kim, and Wonbin Hong, "Wideband 5G N77/N79 4 × 4 MIMO antenna featuring open and closed stubs for metal-rimmed smartphones with four slits," IEEE Antennas and Wireless Propagation Letters, Vol. 22, No. 12, 2798-2802, 2023. Google Scholar

21. Sun, Libin, Yue Li, and Zhijun Zhang, "Wideband decoupling of integrated slot antenna pairs for 5G smartphones," IEEE Transactions on Antennas and Propagation, Vol. 69, No. 4, 2386-2391, 2021. Google Scholar

22. Cheng, Bo and Zhengwei Du, "A wideband low-profile microstrip MIMO antenna for 5G mobile phones," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 2, 1476-1481, 2022. Google Scholar

23. Sun, Libin, Yue Li, and Zhijun Zhang, "Wideband integrated quad-element MIMO antennas based on complementary antenna pairs for 5G smartphones," IEEE Transactions on Antennas and Propagation, Vol. 69, No. 8, 4466-4474, 2021. Google Scholar

24. Chen, Zhe, Yi Liu, Tao Yuan, and Hang Wong, "A miniaturized MIMO antenna with dual-band for 5G smartphone application," IEEE Open Journal of Antennas and Propagation, Vol. 4, 111-117, 2023. Google Scholar

25. Wang, Zhonggen, Wenshi You, Ming Yang, Wenyan Nie, and Weidong Mu, "Design of MIMO antenna with double L-shaped structure for 5G NR," Symmetry, Vol. 15, No. 3, 579, 2023. Google Scholar

26. Ren, Wanying, Zhonggen Wang, Wenyan Nie, Weidong Mu, Chenlu Li, Mingqing Wang, and Wenshi You, "A 12-unit asymmetric mirror-coupled loop antenna for 5G smartphones," Progress In Electromagnetics Research C, Vol. 145, 141-152, 2024.
doi:10.2528/PIERC24061402 Google Scholar

27. Ren, Aidi, Haoran Yu, Lixia Yang, Zhixiang Huang, Zhanhao Zhang, and Ying Liu, "A broadband MIMO antenna based on multimodes for 5G smartphone applications," IEEE Antennas and Wireless Propagation Letters, Vol. 22, No. 7, 1642-1646, 2023. Google Scholar

28. Lin, Han, Wenjie Sun, Zhonggen Wang, and Wenyan Nie, "A dual-band MIMO antenna based on multimode for 5G smartphone applications," Progress In Electromagnetics Research C, Vol. 148, 31-42, 2024. Google Scholar

29. Chen, Horng-Dean, Yuan-Chung Tsai, Chow-Yen-Desmond Sim, and Colin Kuo, "Broadband eight-antenna array design for sub-6 GHz 5G NR bands metal-frame smartphone applications," IEEE Antennas and Wireless Propagation Letters, Vol. 19, No. 7, 1078-1082, 2020. Google Scholar

30. Fang, Yixiang, Yongtao Jia, Jia-Qi Zhu, Ying Liu, and Jiadai An, "Self-decoupling, shared-aperture, eight-antenna MIMO array with MIMO-SAR reduction," IEEE Transactions on Antennas and Propagation, Vol. 72, No. 2, 1905-1910, 2024. Google Scholar

31. Wang, Zhonggen, Mingzhong Li, Ming Yang, Wenyan Nie, Weidong Mu, Han Lin, and Zhongyuan Lu, "Design of wideband 8-element MIMO mobile phone antenna based on sub-6 GHz NR band," Progress In Electromagnetics Research C, Vol. 129, 187-201, 2023. Google Scholar

32. Chen, Zhipeng, Menglin Ye, Zhongxiang Zhang, and Xianliang Wu, "A wideband MIMO antenna with shared radiator for 5G smartphones," 2024 IEEE MTT-S International Wireless Symposium (IWS), 1-3, Beijing, China, 2024.

Professor Zhonggen Wang

Dr. Shunqi Liu

Professor Wenyan Nie

Dr. Ming Yang

Dr. Chenlu Li