A Double-Layer Metal-Only Huygens’ Metasurface Transmitarray

A dual-layer metal-only Huygens’ unit is presented, which consists of double antisymmetric multislot structures without relying on expensive dielectric substrates to achieve a complete 360° phase and high transmission amplitude (−2 dB). Also, the design strategy incorporates extra magnetic resonance, enriches the Huygens resonance, and allows more degrees of freedom to exploit the second harmonic for center frequency multiplication. In order to verify the design scheme, an 18 × 18 transmitarray prototype is created by laser engraving, which consists of two thin metal sheets with a length of 360 mm. The measurement results show a maximum gain of 25 dB, an aperture efficiency of 51.9%, and a 3 dB bandwidth of 10.1%. As a proof of concept, another frequency multiplication design is verified through full-wave simulations to achieve a maximum gain of 26.2 dB at 11.9 GHz under the illumination of a standard pyramid horn with a center frequency of 5.8 GHz.