Tunable triple-band low-frequency metal-water hybrid metamaterial absorber

Abstract This paper proposes a low-frequency absorption metamaterial. The unit cell consists of the rectangular water layer, the metal pattern, the dielectric-slab, the air layer, the organic glass, and a metal backplate. The designed metal-water hybrid metamaterial achieves nearly perfect absorption at 0.45 GHz, 0.65 GHz, and 0.95 GHz. The corresponding absorption is 97.4%, 98.1%, and 98.3%, respectively. Moreover, the simulation results indicate the characteristics of wide-angle incidence and polarization-sensitive. The physical mechanism of the low-frequency absorption is caused by the interaction between electric and magnetic resonances that originate from the metal pattern and water-metal contact surface. Additionally, the designed metamaterial achieves immediately control of the operating frequencies and absorption by adjusting the thickness of the air layer. Measurement results reveal three absorption frequencies within 0–1 GHz, each exceeding 90% absorption. The experimental results are basically consistent with the simulation results. The design provide a valuable approach for implementing tunable devices in the field of low-frequency metamaterial absorption.