High transmittance Huygens' metasurface with 360° phase coverage and its metalens application

Huygens' metasurfaces, as a class of artificial electromagnetic surfaces, have garnered significant interest due to their ability to effectively manipulate electromagnetic wave fronts. In this article, a Huygens' element with a simple design is discussed. The structure comprises a dielectric substrate sandwiched between a reverse-opening resonant ring and a pair of single-opening resonant rings. The proposed structure enables independent modulation of the electrical and magnetic response, particularly delivering transmittance amplitude of at least 0.8 and 0°–360° phase control simultaneously in a single double layer without vias. Based on this structure, we create a Huygens' metasurface focusing lens that gathers plane waves at the focal point. Then, a patch antenna is mounted onto this metalens to transform the radiated spherical waves into plane waves, increasing the antenna gain by up to 11 dBi. The experimental and simulated results demonstrate excellent agreement, demonstrating the usefulness of the proposed metalens and the importance of the designed Huygens-atom for metalens applications.