Gain and isolation improvement techniques for MIMO antenna: A compendious survey

Multiple Input Multiple Output (MIMO) antenna technology plays a vital role in improving the key performance of Wireless communication systems. The performance parameters include high data rates, low latency, expanding channel capacity, increased quality and spectral efficiency, low cost, and compact size. This article explores various design techniques such as metamaterial, metasurface, frequency selective surface (FSS), defected ground structure (DGS), parasitic elements, and orthogonal placements to improve the gain and isolation. The design techniques along with their performance comparison tables are provided. This also includes a proposed MIMO antenna structure with improved gain and isolation by combining two available methods. MIMO antenna performance parameters like correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and channel capacity loss (CCL) are explained. The key challenges of MIMO antenna design and their solution using Intelligent Reflecting Surfaces (IRS) Software-Defined MIMO antennas and Reconfigurable Intelligent Surfaces (RIS) are discussed. The MIMO antenna with improved gain and isolation can be used for applications such as WLAN, Wi-Fi, WiMAX, LTE, ISM, Bluetooth, Radar, Satellite communication, 5G, and beyond 5G communication. This article may be helpful to new researchers working in the area of MIMO antenna.