Metasurface-based coupling suppression for wideband multiple-input-multiple-output antenna arrays

Wideband decoupling requires simultaneous improvements in the performance of an antenna array in its operating band. In this paper, a metasurface structure is proposed to accomplish this difficult task in wideband dual-layer coupled patch multiple-input-multiple-output (MIMO) antenna arrays. The decoupling mechanism is analyzed based on network and field theories, and dual-band response is achieved by incorporating multilayer hybrid split-ring resonators to create a meta-atom equipped with single negative property. By introducing the metasurface into the H-plane coupled MIMO array, the working bandwidth improves from 21.7% to 25.4%, mutual coupling is suppressed to less than -20 dB, gains mostly improve, and radiation patterns are modified. Moreover, the metasurface-based decoupling structure is extended to the E-plane coupled and two-dimensional arrays, exhibiting the same decoupling capability in the 22.9% and 23.6% bandwidths, respectively. Compared with existing metasurface-based decoupling works, the proposed metasurface, which is designed to be coplanar with the array, brings about no change to the array profile and possesses a wider decoupling bandwidth. These results indicate its potential in efficiently decoupling multielement wideband MIMO antenna arrays. (C) 2021 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement