This letter addresses a new approach to improve the gain and isolation of a multiple input multiple output (MIMO) antenna. A C-shaped printed antenna with both ends terminated by a small rectangular section is designed as the basic antenna element for a 2 element MIMO antenna of size 0.8λ×0.67λ×0.04λ (λ, corresponding to lowest operating frequency) which operates over the X band with peak gain of 3 dBi. By introducing a double layered frequency selective surface (FSS) of unit cell dimension 0.2λ×0.2λ×0.0375λ between the two antenna elements as an isolation wall and additionally by placing a 5×3 array of FSS geometry as a reflector below the antenna, the isolation and gain of the two element MIMO antenna are improved by 37 dB and 3 dBi, respectively. The proposed FSS loaded MIMO antenna provides very high isolation about -51 dB (measured) and a very low envelope correlation coefficient (ECC) of 0.000177282 (simulated) using far field approach and 0.000000033414 (calculated measured) using scattering (S) parameter approach. Further MIMO parameters like diversity gain (DG), total active reflection coefficient (TARC), mean effective gain (MEG) and channel capacity loss (CCL) have been evaluated. The radiation pattern is unidirectional in nature with a peak gain about 6 dBi. The letter also presents detailed design guidelines for the proposed FSS loaded MIMO antenna along with their verifications for Ku and K bands. The proposed structure can also be scaled up to a 4 element MIMO antenna.
"Isolation and Gain Improvement of Multiple Input Multiple Output Antenna Using Frequency Selective Surfaces," Progress In Electromagnetics Research Letters,
Vol. 110, 63-71, 2023. doi:10.2528/PIERL23031504
1. Das, G., A. Sharma, R. K. Gangwar, and M. S. Sharawi, "Performance improvement of multi-band MIMO dielectric resonator antenna system with a partially reflecting surface," IEEE Anten. Wire. Propag. Lett., Vol. 18, No. 10, 2105-2109, Oct. 2019. doi:10.1109/LAWP.2019.2938004
2. Kumar, S., A. S. Dixit, R. R. Malekar, H. D. Raut, and L. K. Shevada, "Fifth generation antennas: A comprehensive review of design and performance enhancement techniques," IEEE Access, Vol. 8, 163568-163593, Sept. 2020. doi:10.1109/ACCESS.2020.3020952
3. Si, L., H. Jiang, X. Lv, and J. Ding, "Broadband extremely close-spaced 5G MIMO antenna with mutual coupling reduction using metamaterial-inspired superstrate," Optics Exp., Vol. 27, No. 3, 3472-3482, Feb. 2019. doi:10.1364/OE.27.003472
4. Karimian, R., A. Kesavan, M. Nedil, and T. A. Denidni, "Low-mutual-coupling 60-GHz MIMO antenna system with frequency selective surface wall," IEEE Anten. Wire. Propag. Lett., Vol. 16, 373-376, Jun. 2017. doi:10.1109/LAWP.2016.2578179
5. Garg, P. and P. Jain, "Isolation improvement of MIMO antenna using a novel flower shaped metamaterial absorber at 5.5 GHz WiMAX band," IEEE Trans. on Circuits Systems II: Express Briefs, Vol. 67, No. 4, 675-679, Apr. 2020. doi:10.1109/TCSII.2019.2925148
6. Anudeep, B., K. Krishnamoorthy, and P. H. Rao, "Low-profile, wideband dual-polarized 1 × 2 MIMO antenna with FSS decoupling technique," Int. J. Microw. Wire. Techno., Vol. 14, No. 5, 634-640, Jun. 2022. doi:10.1017/S1759078721000805
7. Mondal, R., P. S. Reddy, D. C. Sarkar, and P. P. Sarkar, "Investigation on MIMO antenna for very low ECC and isolation characteristics using FSS and metal-wall," AEU-Int. J. Electron. Comm., Vol. 135, 1-9, Jun. 2021.
8. Munk, B. A., Frequency Selective Surfaces --- Theory and Design, John Wiley & Sons, New York, 2000. doi:10.1002/0471723770
9. Bhattacharya, A., B. Dasgupta, and R. Jyoti, "A simple frequency selective surface structure for performance improvement of ultra-wideband antenna in frequency and time domains," Inter. J. RF and Microw. Computer-Aided Engg., Vol. 31, No. 11, 1-13, Nov. 2021.
10. Ansys High Frequency Structural Simulator, (HFSS), , Version 16.2.
11. Kumar, G. and K. P. Ray, Broadband Microstrip Antennas, Artech House, Boston, London, 2002.
12. Mishra, M., S. Chaudhuri, R. S. Kshetrimayum, A. Alphones, and K. P. Esselle, "Space efficient meta-grid lines for mutual coupling reduction in two-port planar monopole and DRA array," IEEE Access, Vol. 10, 49829-49838, Jan. 2022. doi:10.1109/ACCESS.2022.3146941