Isolation and Gain Enhancement Using Metamaterial Based Superstrate for MIMO Applications

Abstract

In this paper, a metamaterial superstrate in¬spired multiple-input-multiple-output (MIMO) for gain and isolation enhanced antenna system is investigated for WLAN applications. The superstrate layer generates a resonant cavity effect which results in gain enhancement of the antenna system by 3.73 dBi (65%). The superstrate consists of a novel hexagonal nested ring structure, placed at a height of 0.175λ_0 above antenna and confines the near field coupling between the antenna elements, thereby reducing the mutual coupling. The isolation between each antenna elements is better than 20 dB over the entire band of operation with reduced edge-to-edge spacing of 0.057 λ_0 which makes it suitable for the larger MIMO configurations. The prototype of the proposed design is fabricated and validated through proper measurement that shows the measured impedance bandwidth of 7.0% (5.65–6.06 GHz). The measured gain and simulated efficiency remains above 8.6 dBi and 84% along with envelope correlation coefficient ˂0.003 over the operating band making the design suitable for high gain MIMO WLAN applications.