Highly transmissive bilayer Huygens' metasurface with over 315 degrees phase coverage

We develop a generic approach to design highly transmissive metasurfaces with a full control over the phase of transmitted waves. Our approach allows one to obtain very thin metasurfaces based on a single printed circuit board with specially designed copper patterns on the top and bottom surfaces. The phase control of the transmitted waves is achieved by exploiting the independent tunability of the electric and magnetic resonances of the subwavelength unit cells. In contrast to the previously reported metasurfaces that had multiple layers to maintain high transmissivity over the 2 pi phase range, here we exploit multiple resonators in the same plane to overcome the efficiency limit of the bilayer design. The proposed unit cells are then optimized for a nearly 2 pi phase range at 9 GHz and used to design a focusing lens. The performance of the fabricated lens is characterized by numerical simulations and experiments. (C) 2020 Elsevier GmbH. All rights reserved.