Design of dual-band single-layer metasurfaces for millimeter-wave 5G communication systems

We propose dual-band filters made from a single-layer metasurface for operating on the 28 and 39 GHz bands in mm-wave fifth generation (5G) communication systems. We use the conformational space annealing method, a global optimization technique, and test the usefulness of dual-band metasurfaces through design, fabrication, and measurement with 2916 square-shaped pixels per unit cell defined on a single layer. Each square-shaped pixel has only two states: either filled with metal or free of metal. We were able to obtain transmissive metasurfaces capable of performing three different functions, bandpass/bandpass, bandpass/band-stop, and band-stop/bandpass, by setting three different objective functions applicable to 5G communications. The designed filters have insertion loss of less than 3 dB in the passband region and greater than 20 dB in the stop band region. As a proof-of-concept, we fabricate very thin (50 μm) single-layer metasurfaces etched on only one side of a single dielectric substrate combined with a 5G antenna array to demonstrate high-frequency-selectivity with dual-band operation experimentally.