A Novel Metamaterial Electromagnetic Band Gap (MM-EBG) Isolator to Reduce Mutual Coupling in Low-Profile MIMO Antenna

A low-profile multiple-input/multiple-output (MIMO) antenna of dimension 0.5\(\lambda _{0}\) \(\times \) 0.7\(\lambda _{0}\) is proposed in this communication. This antenna consists of four square radiating patches and a partial ground to which a fractal H-shaped metamaterial electromagnetic band gap (MM-EBG) isolator is etched below the substrate in between the gaps of adjacent pairs of radiating patches or on each arm of intersection of the antenna. The isolator structure is simple to design and is capable of reducing mutual coupling by 15 dB, 16 dB, and 9 dB between antenna elements 1 & 2, 1 & 3, and 1 & 4, respectively. Favorable performance in terms of envelope correlation coefficient (less than 0.1, 0.05, and 0.1) and diversity gain (greater than 9.96, 9.98, and 9.93 dB) with consistent frequency band ranging from 2.53 GHz to 7.3 GHz is exhibited by the proposed MIMO antenna. The results are compared with previous reported literature, and comparative results shows good performance in terms of bandwidth, ECC, diversity gain, and radiation characteristics with improved isolation. Also, an equivalent circuit model of proposed design is presented. The simulated design is validated by fabricating and testing. The measurement of performance parameters closely agree with the simulated ones and have the potential for S and C band applications such as WLAN, WiMAX, IoT, and 5G.