Metal-only anisotropic impedance holographic metasurface

This paper presents a kind of metal-only anisotropic impedance holographic metasurfaces made up of periodic wavelength size-variable meta-atoms. The proposed meta-atom has only two metal layers, i.e. a upper patterned layer carved with cylindrical hollows connecting by a narrow metal cuboid, and a lower grounded layer. The two metal layers are separated by an air gap. The anisotropy of this tensor impedance meta-atom can be skillfully realized by simultaneously controlling the radius of cylindrical hollows and the orientation angle of the narrow metal cuboid. The relationship between the geometrical parameters of the meta-atoms arranged in different positions and the impedance strips with alternating light and shade can be directly mapped based on the integration of the holographic theory and the leaky-wave principle. For proof of concept, two metal-only anisotropic impedance holographic metasurfaces are applied to design linearly polarized broadside pencil beam and dual linearly polarized pencil beams with different radiation angles in the C-band. There is good consistency between the measurements and the simulated results. The satisfactory performance and ultralow profile metal-only structure with reduced fabrication complexity/cost make this proposed design a competitive candidate for space applications.