A Plus-shaped Slot MIMO Antenna with High Reduction Coupling via Hybrid Isolation Technique
Abstract
A compact multi-input multi-output (MIMO) antenna for sub-6 GHz 5G communication is proposed in this article. The proposed antenna consists of a plus-shaped slot with a microstrip feed line positioned inside a rectangular patch after etching a circular slot. The antenna elements are placed oppositely with an edge-to-edge spacing of only 4 mm. To reduce mutual coupling, a hybrid isolation technique consisting of two pairs of vertical and horizontal neutralization lines (NLs) combined with a defected ground structure (DGS) is employed. The proposed technique reduces the mutual coupling below −26 dB in the worst case scenario and achieves a peak isolation of −35 dB over the operating frequency band from 5.17 to 5.47 GHz. The combination of different isolation techniques improves coupling reduction efficiency without increasing the antenna size or inter-element spacing. The final results show an isolation improvement of approximately 14 dB compared to the reference design. The proposed MIMO antenna has compact dimensions of 31 × 31 × 1.6 mm³ and is printed on a low-cost FR-4 substrate. Fabrication and measurement processes were carried out, and the measured results show good agreement with the simulated results. Other antenna performance parameters, including envelope correlation coefficient (ECC), radiation efficiency, and gain, were also investigated. The obtained results demonstrate that the proposed antenna is a suitable candidate for modern sub-6 GHz 5G communication devices.
Keywords
MIMO, isolation, Hybrid isolation technique, mutual coupling reduction
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
M. S. Al Ani, A. Raed Al-Tameemi, G. Hock, T. Kiong, T. Al-Shaikhli and M. Fadhil, "A Plus-shaped Slot MIMO Antenna with High Reduction Coupling via Hybrid Isolation Technique," in Journal of Communications Software and Systems, vol. 23, no. 1, pp. 10-18, October 2026, doi: 10.24138/jcomss-2025-0139
@article{s-al-ani2026plusshaped,
author = {S. Al Ani, Mohammed and Raed Al-Tameemi, Ahmed and Hock, Goh Chin and Kiong, Tiong Sieh and Al-Shaikhli, Taha Raad and Fadhil, Mudhafar},
title = {{A Plus-shaped Slot MIMO Antenna with High Reduction Coupling via Hybrid Isolation Technique}},
journal = {Journal of Communications Software and Systems},
month = oct,
year = {2026},
volume = {23},
number = {1},
pages = {10--18},
doi = {10.24138/jcomss-2025-0139},
url = {https://doi.org/10.24138/jcomss-2025-0139}
}