volume | PIER Journals

Abstract

This paper presents the design of a four-element conformal Multi-Input Multi-Output (MIMO) antenna system for Ultra-Wideband (UWB) applications. It is implemented on a flexible RT Duroid 5880 substrate with a relative permittivity of 2.2, a loss tangent of 0.0009, and a thickness of 0.25 mm. It employs a stepped microstrip line-fed guitar-shaped antenna as a single antenna element. The single antenna element is then arranged orthogonally around the four edges of a 63 × 63 mm² substrate to create a 4-element MIMO system. The four antennas, designated as Ant-1 to Ant-4, have their ground planes connected through L-shaped stubs. The prototypes of single antenna element and 4-element MIMO are built to compare the simulation and measurement findings. The single antenna element is tested under flat, X-bend, and Y-bend cases. It achieves -10 dB impedance bandwidth from 3.14 GHz to over 10.6 GHz, a maximum group delay deviation of 2 ns, and a system fidelity factor greater than 80% in all cases. The 4-element MIMO system was also tested in flat and conformal configurations. It covers a minimum -10 dB impedance bandwidth from 3.5 to 10.8 GHz and exhibits mutual coupling below -18 dB. Its equivalent circuit model is also realized. Its diversity analysis shows an envelope correlation coefficient (ECC) below 0.01, diversity gain (DG) near 10 dB, channel capacity loss (CCL) under 0.4 bits/s/Hz, total active reflection coefficient (TARC) below -10 dB, and mean effective gain (MEG) between -3 dB and -12 dB across the operating band.

1. Federal Communications Commission, "Revision of Part 15 of the commission's rules regarding ultra-wideband transmission systems," First Report and Order FCC 02-48, Washington, DC, 2002.

2. Foschini, G. J. and M. J. Gans, "On limits of wireless communications in a fading environment when using multiple antennas," Wireless Personal Communications, Vol. 6, No. 3, 311-335, 1998.

3. Nella, Anveshkumar and Abhay Suresh Gandhi, "A survey on planar antenna designs for cognitive radio applications," Wireless Personal Communications, Vol. 98, 541-569, 2018.

4. Jhunjhunwala, Vikash Kumar, Tanweer Ali, Pramod Kumar, Praveen Kumar, Pradeep Kumar, Sakshi Shrivastava, and Arnav Abhijit Bhagwat, "Flexible UWB and MIMO antennas for wireless body area network: A review," Sensors, Vol. 22, No. 23, 9549, 2022.
doi:10.3390/s22239549

5. Saeidi, Tale, Idris Ismail, Wong Peng Wen, Adam R. H. Alhawari, and Ahmad Mohammadi, "Ultra-wideband antennas for wireless communication applications," International Journal of Antennas and Propagation, Vol. 2019, No. 1, 7918765, 2019.

6. Khaleel, Haider R., Hussain M. Al-Rizzo, Daniel G. Rucker, and Seshadri Mohan, "A compact polyimide-based UWB antenna for flexible electronics," IEEE Antennas and Wireless Propagation Letters, Vol. 11, 564-567, 2012.

7. Koohestani, M., N. Pires, A. K. Skrivervik, and A. A. Moreira, "Time-domain performance of patch-loaded band-reject UWB antenna," Electronics Letters, Vol. 49, No. 6, 385-386, 2013.

8. Koohestani, Mohsen, Antonio Alves Moreira, and Anja K. Skrivervik, "System fidelity factor evaluation of wearable ultra-wideband antennas for on-body communications," IET Microwaves, Antennas & Propagation, Vol. 9, No. 10, 1054-1058, 2015.

9. Valizade Shahmirzadi, Nooshin and H. Oraizi, "Frequency- and time-domain analysis of a novel reconfigurable microstrip antenna for UWB applications," Journal of Electromagnetic Waves and Applications, Vol. 30, No. 17, 2311-2324, 2016.

10. Wang, Lili, Zhonghong Du, Hailong Yang, Ruoyan Ma, Yuchen Zhao, Xueqi Cui, and Xiaoli Xi, "Compact UWB MIMO antenna with high isolation using fence-type decoupling structure," IEEE Antennas and Wireless Propagation Letters, Vol. 18, No. 8, 1641-1645, 2019.

11. Singh, Ghanshyam, Sachin Kumar, Binod Kumar Kanaujia, and Vijay Kumar Pandey, "Design and implementation of a compact tri-band four-port multiple-input-multiple-output antenna," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 32, No. 8, e23218, 2022.

12. Wang, Lili, Zhonghong Du, Hailong Yang, Ruoyan Ma, Yuchen Zhao, Xueqi Cui, and Xiaoli Xi, "Compact UWB MIMO antenna with high isolation using fence-type decoupling structure," IEEE Antennas and Wireless Propagation Letters, Vol. 18, No. 8, 1641-1645, 2019.

13. Khedr, Amira A., Basem E. Elnaghi, and Ahmed M. Mohamed, "Design of a compact dual port 2 × 1 ultra-wideband MIMO antenna for radio frequency energy harvesting based on four ``A" shaped slots," Progress In Electromagnetics Research M, Vol. 128, 41-49, 2024.
doi:10.2528/PIERM24051805

14. Kumar, Praveen, Sameena Pathan, Om Prakash Kumar, Shweta Vincent, Yashwanth Nanjappa, Pradeep Kumar, Pranav Shetty, and Tanweer Ali, "Design of a six-port compact UWB MIMO antenna with a distinctive DGS for improved isolation," IEEE Access, Vol. 10, 112964-112974, 2022.

15. Mohanty, Asutosh and Sudhakar Sahu, "Design of 8-port compact hybrid fractal UWB MIMO antenna with a conjoined reflector-ground integration for isolation improvement," AEU --- International Journal of Electronics and Communications, Vol. 145, 154102, 2022.

16. Kannappan, Lekha, Sandeep Kumar Palaniswamy, Malathi Kanagasabai, Preetam Kumar, M. Gulam Nabi Alsath, Sachin Kumar, Thipparaju Rama Rao, Mohamed Marey, Apeksha Aggarwal, and Jayaram K. Pakkathillam, "3-D twelve-port multi-service diversity antenna for automotive communications," Scientific Reports, Vol. 12, No. 1, 403, 2022.

17. Nadeem, Iram and Dong-You Choi, "Study on mutual coupling reduction technique for MIMO antennas," IEEE Access, Vol. 7, 563-586, 2018.

18. Kumar, Amit, Abdul Quaiyum Ansari, Binod Kumar Kanaujia, Jugul Kishor, and Ladislau Matekovits, "A review on different techniques of mutual coupling reduction between elements of any MIMO antenna. Part 1: DGSs and parasitic structures," Radio Science, Vol. 56, No. 3, 1-25, 2021.

19. Sharawi, Mohammad S., "Current misuses and future prospects for printed multiple-input, multiple-output antenna systems [wireless corner]," IEEE Antennas and Propagation Magazine, Vol. 59, No. 2, 162-170, 2017.

20. Abdelghany, Mahmoud A., M. Fathy Abo Sree, Arpan Desai, and Ahmed A. Ibrahim, "4-port octagonal shaped MIMO antenna with low mutual coupling for UWB applications," Computer Modeling in Engineering & Sciences, Vol. 136, No. 2, 1999-2015, 2023.
doi:10.32604/cmes.2023.023643

21. Thakur, Ekta, Naveen Jaglan, and Samir Dev Gupta, "Miniaturized four-port UWB MIMO antennas with triple-band rejection using single EBG structures," International Journal of Microwave and Wireless Technologies, Vol. 14, No. 2, 185-193, 2022.

22. Kumar, Sachin, Gwan H. Lee, Dong H. Kim, Wahab Mohyuddin, Hyun C. Choi, and Kang W. Kim, "Multiple-input-multiple-output/diversity antenna with dual band-notched characteristics for ultra-wideband applications," Microwave and Optical Technology Letters, Vol. 62, No. 1, 336-345, 2020.

23. Rao, Praveen Kumar and Rajan Mishra, "Elliptical shape flexible MIMO antenna with high isolation for breast cancer detection application," IETE Journal of Research, Vol. 69, No. 1, 325-333, 2023.

24. Zhang, Jie, Chengzhu Du, and Ruohui Wang, "Design of a four-port flexible UWB-MIMO antenna with high isolation for wearable and IoT applications," Micromachines, Vol. 13, No. 12, 2141, 2022.
doi:10.3390/mi13122141

25. Liu, Han, Guoqin Kang, and Shuiqiao Jiang, "Compact dual band‐notched UWB multiple‐input multiple‐output antenna for portable applications," Microwave and Optical Technology Letters, Vol. 62, No. 3, 1215-1221, 2020.

26. Jayant, Shailesh, Garima Srivastava, and Sachin Kumar, "Quad-port UWB MIMO footwear antenna for wearable applications," IEEE Transactions on Antennas and Propagation, Vol. 70, No. 9, 7905-7913, 2022.

27. Aboelleil, Heba, Ashraf A. M. Khalaf, and Ahmed A. Ibrahim, "Quad ports flexible MIMO antenna with connected ground and high isolation for UWB applications," Analog Integrated Circuits and Signal Processing, Vol. 120, No. 1, 59-70, 2024.

28. Desai, Arpan, Jayshri Kulkarni, M. M. Kamruzzaman, Štěpán Hubálovský, Heng-Tung Hsu, and Ahmed A. Ibrahim, "Interconnected CPW fed flexible 4-port MIMO antenna for UWB, X, and Ku band applications," IEEE Access, Vol. 10, 57641-57654, 2022.
doi:10.1109/ACCESS.2022.3179005

29. Rajesh, G. and R. Poonkuzhali, "Design and analysis of CPW fed ultrathin flexible MIMO antenna for UWB and X-band applications," IEEE Access, Vol. 12, 96704-96717, 2024.

30. Desai, Arpan, Heng-Tung Hsu, Basma M. Yousef, Allam M. Ameen, Yi-Fan Tsao, and Ahmed A. Ibrahim, "UWB connected ground transparent 4-port flexible MIMO antenna for IoT applications," IEEE Internet of Things Journal, Vol. 11, No. 7, 12475-12484, 2024.

31. Agrawall, N. P., G. Kumar, and K. P. Ray, "Wide-band planar monopole antennas," IEEE Transactions on Antennas and Propagation, Vol. 46, No. 2, 294-295, 1998.

32. Singh, Ghanshyam, Sachin Kumar, Binod Kumar Kanaujia, and Vijay Kumar Pandey, "Design and performance analysis of a frequency reconfigurable four-element multiple-input-multiple-output antenna," AEU --- International Journal of Electronics and Communications, Vol. 146, 154118, 2022.

Mr. Sandeep Kiran Vattiprolu

Dr. Pullagura Rajesh Kumar