A Compact Circularly Polarized MIMO Antenna using RIS Metasurface for WI-FI 7 Applications

A compact circularly polarized (CP) multiple input multiple output (MIMO) antenna integrated with a reactive impedance surface based metasurface (RIS-MS) for Wi-Fi 7 applications is proposed in this paper. The proposed metasurface based MIMO antenna comprises two layers, layer one has four pentagonal patch radiators, and layer two consists of an array of 7 x 7 square RIS-MS. The RIS-MS is placed between the radiating patches and the ground plane. The RIS-MS significantly enhances the antenna’s performance, resulting in a wide impedance bandwidth (IBW), axial ratio bandwidth (ARBW), and high gain over the Wi-Fi 7 frequency range. Simulated and measured results show that the proposed MIMO antenna provides an IBW of 40.6% (5.1 - 7.7 GHz), an ARBW of 34.75% (5.35 - 7.6 GHz), and a peak gain of 10.4 dBic. Furthermore, the proposed antenna exhibits excellent MIMO diversity performance, with an isolation greater than 25 dB between all radiating elements. The calculated envelop correlation coefficient (ECC) and diversity gain (DG) values remain below 0.002 and above 9.5 dB, respectively, indicating low correlation and good diversity performance among the antenna elements. In addition, the realized gain, radiation efficiency, channel capacity loss (CCL), Total active reflection coeefficient (TARC) are evaluated over the operating bandwidth to determine the MIMO diversity performance of the proposed antenna.