Investigation of Isolation Enhancement Techniques for Electrically Small MIMO Antennas

The growing need for faster data rates and improved spectral efficiency in contemporary wireless communication systems has resulted in the widespread utilization of multiple-input-multiple-output (MIMO) antennas. Nevertheless, the process of incorporating many antennas into small devices like mobile handsets poses considerable difficulties in terms of the interaction and separation between the antenna components. In order to tackle these difficulties, researchers have put forward many methods to promote isolation in electrically small MIMO antennas. This review offers a thorough examination of the most advanced techniques and approaches used to improve the separation between densely positioned MIMO antenna elements. These techniques facilitate the implementation of extremely small and efficient MIMO antenna systems that may be seamlessly incorporated into various wireless communication devices. The key methodologies addressed involve the design and execution of decoupling and matching networks. These networks effectively separate antenna parts and improve the overall impedance matching, resulting in increased isolation between ports. Also, this review thoroughly examines the use of electromagnetic band-gap (EBG) and meta material-inspired structures positioned between antenna elements to suppress surface waves and minimize coupling. The objective of this work is to offer significant insights and direction for the enhancement of advanced MIMO antenna systems, focusing on improving isolation performance.