eng Science and Education Publishing American Journal of Electrical and Electronic Engineering 2328-7357 2025-09-04 13 1 10 14 10.12691/ajeee-13-1-2 AJEEE20251312 article Nassrin Ibrahim Mohamed Elamin 1 Mohammed Gronfula nassrin.elamin@alasala.edu.sa 1 Department of Engineering, Alasala Collages, Dammam, Kingdom of Saudi Arabia This paper explores the impact of mutual coupling on the performance of MIMO systems, particularly in 5G microstrip antennas. Through simulations, we investigate the coupling effect in a proposed Microstrip Patch Antenna (MPA) design. A single-element MPA and a 4-element antenna array are designed to analyze mutual coupling and improve isolation by introducing slots, thereby increasing the data rate. The slotted single microstrip antenna achieves a 175% bandwidth improvement, covering 27.6 GHz to 29.7 GHz at a center frequency of 28 GHz. The results show that the 4-element slotted microstrip MIMO antenna system reduces mutual coupling to -16.675 dB, outperforming the not slotted design (-14.4 dB). This work aims to design a single-band 4-element MIMO microstrip antenna for 5G systems, enhancing bandwidth, reducing mutual coupling, and achieving high data rates, polarization, bandwidth (>1 GHz), and realized gain at 28 GHz. https://pubs.sciepub.com/ajeee/13/1/2/ajeee-13-1-2.pdf 28 GHz antennas MIMO slotted microstrip antenna 5G applications