Wideband Metasurface-Based MIMO antenna for Sub-6 GHz 5G Applications

A compact MIMO antenna utilizing a metasurface (MS) is introduced for sub-6 GHz applications, offering wideband functionality and high isolation characteristics. Each individual element of the antenna consists of a slot coupled with $2\times 2$ unit cells of the MS. To effectively reduce mutual coupling, metallic vias are occupied so that the MS of each MIMO element is grounded at certain points. The proposed antenna stands out from other reported designs due to its simplicity in the decoupling structure without requiring additional space, its compact size, and its ability to operate across a wide frequency range. The overall dimensions of the proposed antenna are $0.85\lambda_{c}\times 0.48\lambda_{c}\times 0.03\lambda_{c}$ (where $\lambda_{c}$ is the free-space wavelength at center operating frequency), with a center-to-center element spacing of $0.43\lambda_{c}$. The antenna offers an operating bandwidth of 17.1% (3.64-4.32 GHz) and achieves high isolation of over 27 dB. The proposed decoupling method is also applicable to multi-element MIMO antennas.