A Metasurface Wall for Isolation Enhancement: Minimizing mutual coupling between MIMO antenna elements

A ±45°, dual-polarized, high-isolation, 1 × 2 multiple-input, multiple-output (MIMO) antenna array for wideband microbase-station application is presented in this article. The proposed antenna element incorporates two perpendicular magnetic coupling feeding (MCF) networks and an H-shaped slot in the ground plane to improve the port isolation. Simulation results indicate that it has an isolation of more than 38 dB. To suppress the mutual coupling between antenna elements, a dual wall consisting of a novel metasurface structure is introduced. When spatial-wave incidents occur, the isolation wall can restrain the electromagnetic wave propagation. The electromagnetic waves produce resonance on the wall surface, which scatters some of the resonance, while the rest is transmitted to the ground and weakened by the decoupling structure between two elements. The metasurface walls, which are inserted vertically between the antenna elements, improve the isolation by roughly 5.9 dB within the 2.5-2.7-GHz frequency band and reach a maximum of -22.8 dB at approximately 2.6 GHz. The proposed antenna has been fabricated, and the experimental results are near the simulation responses.