Single-Layer Four-Band, Dual Linear Polarization Reflective Metasurface

This paper presents a novel single-layer dual-linear polarization unit cell design for a four-band reflectarray antenna centered at 6, 8.5, 11.5, and 14.5 GHz. A reflectarray antenna consists of a passive element array of individual substrates and printed structures. The article highlights the challenges of designing reflectarray antennas under single-layer sharedaperture conditions, difficulties due to physical interference and element coupling. During the design phase, we found that the coincidence of length values between different geometric structures will bring strong coupling. At the same time, we also found that when different geometric structures are on the extension line of each other, it will also bring strong coupling. When strong coupling occurs between dissimilar geometries, the structures in the cell lose the ability to independently control phase shifts at one frequency. By careful design of each element, the phase of the reflected wave can be tuned to formulate the phase distribution on the surface. The article presents simulation results for a four-frequency reflectarray surface that achieves independent deflection for each frequency while keeping the polarization direction of the incident wave constant. The article concludes with a discussion of the potential impact of these developments on future designs.