In the modern era, the eminent increase of wireless devices, inadequate bandwidth, and limited channel capacity have substantially promoted efforts to develop advanced standards for communication networks. Subsequently, this has promoted the development of next-generation (5G) communications systems at the mm-wave spectrum featuring much greater channel capacity and higher data rates. The forthcoming 5G technology provides significantly increased reliability, high data rate requirements, and low power consumption to meet the massive increase in linked devices. It promises to improve the prospects of emerging technologies such as virtual reality and smart cities. However, critical limitations at the mm-wave spectrum, such as signal fading, atmospheric absorptions, and path loss attenuations, need to be resolved, which becomes more significant with the single antenna. Multiple-input multiple-output (MIMO) antenna has been determined to be a key enabling technology for current and future wireless systems, demonstrating the concurrent operation of multi-antennas, increasing channel capacity along with the benefits of high data rates and throughput of Gigabits/sec. The 5th generation MIMO antenna requires high bandwidth for concurrent functioning.

In contrast, a high gain is needed to reduce atmospheric diminutions and absorptions at mm-wave frequencies, and the compactness of the structure is required to facilitate assimilation in MIMO systems. In addition, the challenges associated with MIMO antenna design include designing closely packed antenna elements with reduced mutual coupling and high isolation, subsequently improving the antenna performance. The multi-element antenna arrays exhibit the same capacity as the single antenna because the antenna arrays are likewise fed with a single port. Conversely, MIMO antennas demonstrate multipath propagation with a higher data rate, increased capacity, and link reliability, which are the main features of 5G.