Broadband and ultrathin Huygens metasurface with high transmittance

Thickness and performance are two critical issues to be considered simultaneously in designing transmission-type meta-devices. In this paper, a general design methodology is proposed to achieve a broadband and ultrathin Huygens metasurface (HMS) with high transmittance. By using the asymmetry of structures to excite the magnetic response, the Huygens meta-atom can be as thin as lambda/26.3. Physical and geometric analyses of the meta-atom show that its electric and magnetic responses can be independently controlled, which provides a method to enlarge the bandwidth of the HMS with high transmittance. We demonstrate that the proposed meta-atoms can cover full phase range of 360. and present high transmittance with the minimum amplitude of -2.75 dB at the working frequency of 10.2 GHz. A prototype of transmitarray composed of the proposed meta-atoms is designed, fabricated, and tested. Both numerical and experimental results validate the excellent performance of the transmitarray. The measured bandwidth in terms of 3 dB gain is 9.8%, and the measured gain at 10.2 GHz is 28.4 dBi, resulting in 43.0% aperture efficiency.