1-bit Wideband Reconfigurable Intelligent Surface Design at Sub-6 Band

In this paper, a 1-bit wideband reconfigurable intelligent surface (RIS) design operating at sub-6 band is proposed. The unit cells of the RIS surface are designed based on a three-layer stacked patch structure. Employing a 1-bit PIN diode to reconfigure the phase states, a phase difference of 180⁰ pm 20⁰ is observed over the frequency range of 4.81 -5.77 GHz, corresponding to a 19.2% fractional bandwidth. The reflection magnitude of the unit cell is above -3 dB in the band of interest, and the cross-polarization of the scattered waves is found significantly lower than the single-patch structure. The RIS array with a dimension of 8.2λ λ 5.1λ, corresponding to a 16 λ 10 array is structured according to the proposed unit cell with good beam steering capabilities.