Metamaterial absorber and extending absorbance bandwidth based on multi-cross resonators

In this paper, we report the design, simulation, and measurements of a broadband metamaterial absorber (MA) based on a periodic array of multi-layer cross-structure resonators. A perfect narrowband MA consists of cross-structure resonator, dielectric substrate, and continuous metal films, and the absorption frequency can be tunable by changing the geometrical parameters based on L-C resonance circuit theory. Furthermore, the absorption band of our design is effectively extended by simply stacking several such structural layers with different geometrical dimensions. Finally, the 4-layer cross-structure MA is only 2 mm, which can achieve a full width at half maximum (FWHM) bandwidth of 2 GHz by numerical simulations, and 90 % bandwidth of 1.9 GHz by experiments.