This paper proposes a four-port rectangular monopole antenna for ultra-wideband multiple-input multiple-output (UWB-MIMO) applications. The proposed antenna was designed by using step etching on the ground plane and arrow-shaped slot etching on a radiating patch to enhance bandwidth and improve performances. The homogeneous elements and angular variation techniques were applied to reduce mutual coupling between multiple antenna elements. The structural simulation technique used Computer Simulation Technology (CST) program to analyze the antenna characteristics such as reflection coefficient, group delay, mutual coupling, envelope correlation coefficient, and radiation patterns. The measured results were found to cover a frequency range of 3.1-10.6 GHz for UWB communications. The envelope correlation coefficient for the MIMO system was obtained under 0.001 which is less than the specific parameters of UWB-MIMO antennas. The radiation pattern was bi-directional. Also, the efficiency of the four-port antenna was more than 85.70%.
2. Wang, Z., L. Liu, J. Cai, Z. Shao, Y. Yang, and X. Zhu, "2.4 GHz/5 GHz wide-band receiver in a wireless communication system based on 4 x 4 MIMO technology," 2012 International Conference on Computational Problem-Solving (ICCP), 182-185, 2012.
3. Kim, S.-H., J.-Y. Lee, T. T. Nguyen, and J.-H. Jang, "High-performance MIMO antenna with 1-D EBG ground structures for handset application," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 1468-1471, 2013.
4. Jiang, X., H. Wang, and T. Jiang, "A low mutual coupling MIMO antenna using EBG structures," 2017 Progress In Electromagnetics Research Symposium | Spring (PIERS), Vol. 12, 660-663, St. Petersburg, Russia, May 22-25, 2017.
5. Sun, Y., Q. Huang, and X. Shi, "A low mutual coupling MIMO antenna using EBG structures," 2016 IEEE International Conference on Microwave and Millimeter Wave Technology (ICMMT), Vol. 2, 701-703, 2016.
6. Numan, A.-B., M.-S. Sharawi, A. Steffes, and D.-N. Aloi, "A defected ground structure for isolation enhancement in a printed MIMO antenna system," 2013 7th European Conference on Antennas and Propagation (EuCAP), 2123-2126, 2013.
7. Jusoh, M., M. F. B. Jamlos, M. R. Kamarudin, and M. F. B. A. Malek, "A MIMO antenna design challenges for UWB application," Progress In Electromagnetics Research, Vol. 36, 357-371, 2012.
8. Rakluea, P. and P. Poch, "Development of circular ring antennas for mobile broadband systems," 2015 7th International Conference on Information Technology and Electrical Engineering (ICITEE), 530-533, 2015.
9. Najam, A. I., Y. Duroc, and S. Tedjini, "Design and analysis of MIMO antennas for UWB communications," Proceedings of the Fourth European Conference on Antennas and Propagation, 1-5, 2010.
10. Jusoh, M., M. F. Jamlos, M. F. Malek, M. R. Kamarudin, and H. Harun, "Analysis of radiation efficiency effects on UWB MIMO tree-antenna positioning," 2012 Asia-Pacific Symposium on Electromagnetic Compatibility, 897-900, 2012.
11. Dao, M.-T., V.-A. Nguyen, Y.-T. Im, S.-O. Park, and G. Yoon, "3D polarized channel modeling and performance comparison of MIMO antenna configurations with different polarizations," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 7, 2672-2682, 2011.
12. Kumar, R. and N. Pazare, "Compact printed ultra-wideband diversity monopole antenna with slantinverted tree-shaped stub," IET Microwaves, Antennas & Propagation, Vol. 9, No. 14, 1595-1604, 2015.
13. Naktong, W., S. Kornsing, P. Boonmaitree, P. Dabbung, and A. Ruengwaree, "Study of geometryshaped monopole antenna with step-shaped etching technique on ground plane," 2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technolog (ECTI-CON), 1-4, 2016.
14. Saad-Bin-Alam, Md., M. S. Ullah, and S. Moury, "Design of a narrowband 2.45 GHz unidirectional microstrip antenna with a reversed `Arrow' shaped slot for fixed RFID tag and reader," 2013 2nd International Conference on Advances in Electrical Engineering (ICAEE), 301-304, 2013.
15. Thongbor, P., A. Ruengwaree, V. Pirajnanchai, W. Naktong, and N. Fhafhiem, "Rectangular monopole antenna with arrow-shaped slot etching for UWB-MIMO application," 2016 13th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technolog (ECTI-CON), 1-4, 2016.
16. Werfelli, H., K. Tayari, M. Chaoui, M. Lahiani, and H. Ghariani, "Design of rectangular microstrip patch antenna," 2016 2nd International Conference on Advanced Technologies for Signal and Image Processing (ATSIP), 798-803, 2016.
17. Balanis, C. A., Antenna Theory: Analysis and Design, John Wiley & Sons, 2016.
18. Yadav, M. B., B. Singh, and V. S. Melkeri, "Design of rectangular microstrip patch antenna with DGS at 2.45 GHz," 2017 International Conference of Electronics, Communication and Aerospace Technology (ICECA), Vol. 1, 2017.
19. Simons, R. N., , Vol. 165, 367-370, Coplanar Waveguide Circuits, Components, and Systems, John Wiley & Sons, 2004.
20. Li, X. F., "Design of a CPW-fed wideband planar monopole antenna with omni-directional pattern improvement," 2015 IEEE International Conference on Communication Problem-Solving (ICCP), 271-273, 2015.
21. Federal Communications Commission, Revision of part 15 of the commission's rules regarding ultra-wideband transmission systems: First report and order, FCC 02.V48, April 2002.
22. Jan, J.-Y., J.-C. Kao, Y.-T. Cheng, W.-S. Chen, and H.-M. Chen, "CPW-fed wideband printed planar monopole antenna for ultra-wideband operation," 2006 IEEE Antennas and Propagation Society International Symposium, Vol. 59, No. 7, 1697-1700, 2006.
23. Yoon, H. K., W. S. Kang, Y.-J. Yoon, and C.-H. Lee, "A CPW-fed flexible monopole antenna for UWB systems," 2007 IEEE Antennas and Propagation Society International Symposium, 701-704, 2007.
24. Matin, M. A., "Ultra wideband: Current status and future trends," BoD --- Books on Demand, 2012.
25. Manteuffel, D., "MIMO antenna design challenges," 2009 Loughborough Antennas & Propagation Conference, 50-56, 2009.
26. Vaughan, R. G. and J. B. Andersen, "Antenna diversity in mobile communications," IEEE Transactions on Vehicular Technology, Vol. 36, No. 4, 149-172, 1987.
27. Najam, A. I., Y. Duroc, and S. Tedjini, "A four-element Ultra Wideband (UWB) diversity antenna," 2010 IEEE Antennas and Propagation Society International Symposium, 1-4, 2010.
28. Dama, Y., A. S. Hussaini, R. A. Abd-Alhameed, S. M. R. Jones, N. J. McEwan, T. Sadeghpour, and J. Rodriguez, "Envelope correlation formula for (N, N) MIMO antenna array including power losses," 2011 18th IEEE International Conference on Electronics, Circuits, and Systems, 508-511, 2011.
29. Tripathi, S., A. Mohan, and S. Yadav, "A compact Koch fractal UWB MIMO antenna with WLAN band-rejection," IEEE Antennas and Wireless Propagation Letters, Vol. 14, 1565-1568, 2015.
30. Wu, W., B. Yuan, and A. Wu, "A quad-element UWB-MIMO antenna with band-notch and reduced mutual coupling based on EBG structures," International Journal of Antennas and Propagation, Vol. 2018, Article ID 8490740, 10 pages, 2018.
31. Muhammad, B., S. Rashid, A. Hammad, S. Muhammad Farhan, and B. Anthony, "An FSS-based nonplanar quad-element UWB-MIMO antenna system," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 987-990, 2016.
32. Deepika, S., A. Mahesh, and K. Shiban Kishen, "Easily extendable compact planar UWB MIMO antenna array," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 2328-2331, 2017.
33. Ahmed, I., M. Jan, and S. Raed, "Compact UWB MIMO antenna with pattern diversity and band rejection characteristics," Microwave and Optical Technology Letters, Vol. 59, No. 6, 1460-1464, 2017.
34. Wael, A. E. A. and I. Ahmed, "A compact double-sided MIMO antenna with an improved isolation for UWB applications," AEU --- International Journal of Electronics and Communications, Vol. 82, 7-13, 2017.
35. Rifaqat, H., S. Mohammad, and S. Atif, "An integrated four-element slot-based MIMO and a UWB sensing antenna system for CR platforms," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 2, 978-983, 2017.
36. Mohamed, S., S. Mohamed Sameh, and M. Hassan, "Dual notched band quad-element MIMO antenna with multitone interference suppression for IR-UWB wireless applications," IEEE Transactions on Antennas and Propagation, Vol. 66, No. 11, 5737-5746, 2018.
37. Tang, Z., X. Wu, J. Zhan, S. Hu, Z. Xi, and Y. Liu, "Compact UWB-MIMO antenna with high isolation and triple band-notched characteristics," Applied Sciences, Vol. 7, 19856-19865, 2019.
38. Fatima, A., S. Rashid, S. Tayyab, B. Muhammad, and S. Farhan, "A compact quad-element UWB-MIMO antenna system with parasitic decoupling mechanism," Applied Sciences, Vol. 9, No. 11, 2371, 2019.
39. Kunal, S., K. Ashwani, K. Binod, D. Santanu, and K. Sachin, "A CPW-fed UWB MIMO antenna with integrated GSM band and dual band notches," International Journal of RF and Microwave Computer-Aided Engineering, Vol. 29, No. 1, e21433, 2019.
40. Kamel Salah, S. and A. Haythem Hussein, "Planar UWB MIMO-diversity antenna with dual notch characteristics," Progress In Electromagnetics Research, Vol. 93, 119-129, 2019.