Dual-band single negative metamaterial-based MIMO antenna with enhanced performance

This work presents a single-layer metasurface characterization and analysis for converting a linearly polarised narrowband antenna to a wideband circularly polarised antenna and its multiple-input-multiple-output (MIMO) implementation. The single-layer metasurface is supported by grounded dielectric substrate, which is considered wave-guided metamaterial to retrieve the effective refractive index along the propagation direction. The proposed metasurface shows dual-band single negative (SNG) properties, with the first band (3 to 5.9 GHz) having negative permittivity and the second band (5.9 to 9 GHz) having negative permeability, which increases the effective propagation constant and thus allows antenna miniaturisation. The metasurface-integrated MIMO antenna has a wide impedance bandwidth of 3.11 GHz (4.3–7.41 GHz), an axial ratio bandwidth of 1.6 GHz (4.7–6.3 GHz), and the antenna gain ranges from 4.8 to 7.8 dB across the impedance bandwidth.