In this paper a novel design to reduce mutual coupling in circular patch antennas is proposed. A circular MIMO antenna with a dumb-bell shape parasitic element is inserted between the two circular patch antennas thereby reducing the mutual coupling. It has been observed that the proposed design produces a multi-band characteristics at 3.1 GHz, 6.2 GHz & 7.7 GHz. At the tri-band frequencies impedance bandwidths (IBW's) are around 90 MHz, 320 MHz, and 540 MHz. The process involves cutting rectangular slits on each side of a circular patch and placing a dumb-bell shaped parasitic structure to reduce the transmission coefficient (S12) to -40.75 dB. It is observed that the antenna parameters are greatly improved in terms of ECC, diversity gain, directivity, group delay and peak gain which are 0.005, 9.973 dBi, 6.14 dBi, 10.81±1 nsec and 3.59 dBi. The results of experimental validation and numerical analysis are presented. The antenna design can be used for wireless communication as well as all C-band applications.
2. Irene, G. and A. Rajesh, "A dual-polarized UWB-MIMO antenna with IEEE 802.11 ac bandnotched characteristics using split-ring resonator," Journal of Computational Electronics, 1-9, 2018.
3. Chacko, B. P., G. Augustin, and T. A. Denidni, "Uniplanar slot antenna for ultrawideband polarization-diversity applications," IEEE Antennas and Wireless Propagation Letters, Vol. 12, 88-91, 2013.
4. Babu, K. V. and B. Anuradha, "Design of Multi-band Minkowski MIMO Antenna to reduce the mutual coupling," Journal of King Saud University-Engineering Sciences, 2018.
5. Li, W. T., et al., "Novel printed filtenna with dual notches and good out-of-band characteristics for UWB-MIMO applications," IEEE Microwave and Wireless Components Letters, Vol. 26, No. 10, 765-767, 2016.
6. Toktas, A., "G-shaped band-notched ultra-wideband MIMO antenna system for mobile terminals," IET Microwaves, Antennas & Propagation, Vol. 11, No. 5, 718-725, 2016.
7. Elsheakh, D. M. N., M. F. Iskander, E. A. Abdallah, H. A. Elsadek, and H. Elhenawy, "Microstrip array antenna with new 2D-electromagnetic band gap structure shapes to reduce harmonics and mutual coupling," Progress In Electromagnetics Research C, Vol. 12, 203-213, 2010.
8. Liu, Y.-Y. and Z.-H. Tu, "Compact differential band-notched stepped-slot UWB-MIMO antenna with common-mode suppression," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 593-596, 2017.
9. Tang, T.-C. and K.-H. Lin, "An ultra-wideband MIMO antenna with dual band-notched function," IEEE Antennas and Wireless Propagation Letters, Vol. 13, 1076-1079, 2014.
10. Lee, C.-H., S.-Y. Chen, and P. Hsu, "Integrated dual planar inverted-F antenna with enhanced isolation," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 963-965, 2009.
11. Krishna, R. V. S. Ram and R. Kumar, "A dual-polarized square-ring slot antenna for UWB, imaging, and radar applications," IEEE Antennas and Wireless Propagation Letters, Vol. 15, 195-198, 2016.
12. Lin, G.-S., et al., "Isolation improvement in UWB MIMO antenna system using carbon black film," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 222-225, 2017.
13. Zhang, S., et al., "Ultrawideband MIMO/diversity antennas with a tree-like structure to enhance wideband isolation," IEEE Antennas and Wireless Propagation Letters, Vol. 8, 1279-1282, 2009.
14. Zhao, Y., F.-S. Zhang, L.-X. Cao, and D.-H. Li, "A compact dual band-notched MIMO diversity antenna for UWB wireless applications," Progress In Electromagnetics Research C, Vol. 89, 161-169, 2019.
15. Chiu, C.-W., C.-H. Chang, and Y.-J. Chi, "A meandered loop antenna for LTE/WWAN operations in a smart phone," Progress In Electromagnetics Research C, Vol. 16, 147-160, 2010.
16. Chung, Y., et al., "High isolation dual-polarized patch antenna using integrated defected ground structure," IEEE Microwave and Wireless Components Letters, Vol. 14, No. 1, 4-6, 2004.
17. Mak, A. C. K., C. R. Rowell, and R. D. Murch, "Isolation enhancement between two closely packed antennas," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 11, 3411-3419, 2008.
18. Li, J.-F., et al., "Compact dual band-notched UWB MIMO antenna with high isolation," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 9, 4759-4766, 2013.
19. Wong, K.-L., B.-W. Lin, and B. W.-Y. Li, "Dual-band dual inverted-F/loop antennas as a compact decoupled building block for forming eight 3.5/5.8-GHz MIMO antennas in the future smartphone," Microwave and Optical Technology Letters, Vol. 59, No. 11, 2715-2721, 2017.
20. Mathur, R. and S. Dwari, "Compact CPW-fed ultrawideband MIMO antenna using hexagonal ring monopole antenna elements," AEU — International Journal of Electronics and Communications, 2018.
21. Dabas, T., et al., "Mutual coupling reduction between elements of UWB MIMO antenna using small size uniplanar EBG exhibiting multiple stop bands," AEU — International Journal of Electronics and Communications, 2018.
22. Khan, M. S., et al., "A compact CSRR-enabled UWB diversity antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 16, 808-812, 2017.
23. Li, Y. and G. Yang, "Dual-mode and triple-band 10-antenna handset array and its multipleinput multiple-output performance evaluation in 5G," International Journal of RF and Microwave Computer-Aided Engineering, e21538, 2018.
24. Babu, K. B. V. and B. Anuradha, "Tri-band MIMO antenna for WLAN, WiMAX and defence system & radio astronomy applications," Advanced Electromagnetics, Vol. 7, No. 2, 60-67, 2018.
25. Srinivasa Rao, P., K. J. Babu, and A. M. Prasad, "Compact multi-band MIMO antenna with improved isolation," Progress In Electromagnetics Research M, Vol. 62, 199-210, 2017.