A flexible metamaterial absorber with four bands and two resonators

An efficient approach for achieving more resonance bands with fewer resonators is proposed in this paper. We investigate the theory, design, simulation, fabrication, and performance of a flexible metamaterial perfect absorber (MPA) with two resonators and four resonances located in GHz and THz ranges. The sandwich microstructure of the MPA consists of periodic “回” shaped metal patches on a metasurface, a dielectric of FR4 board on the interlayer, and a continuous copper film on the substrate. The four peaks of absorptivity owing to the coupling effect of the strong LC and surface resonance of the outer ring resonator as well as the strong LC and surface resonance of the inner ring resonator are 93.887%, 99.479%, 98.296%, and 93.035% at 38.165 GHz, 155.48 GHz, 231.71 GHz, and 275.27 GHz, respectively. The influences on absorptivity produced by angles, dimensions, and materials are also studied. The proposed MPA, equipped with strong flexibility, ultrathin thickness, light weight, strong absorption, sparks inspirations in designing the MPA with more resonances and fewer resonators. •Periodic“回”shaped metal patches produce four absorption bands.•The max absorptivity is 99.479% and the four peaks are all greater than 90%.•The total FWHM is 17.02 GHz.•The MPA owns strong absorption, ultrathin thickness and convenient process.•The MPA can be applied in bolometers, micrometer and stealth materials.