A dual-band metamaterial absorber with adjacent absorption peaks

A kind of nearly perfect metamaterials absorber (MMA) with super-close dual bands is designed and fabricated at microwave frequency. This super-compact and space saving structure integrates a cross-shaped resonator (CSR) and complementary cross-shaped resonator (CCSR) in one unit cell, corresponding to lower and higher resonances, respectively. This dual-band polarization-insensitive MMA operates well with a wide range of incident angles for TE polarization. On the other hand, the higher absorptive resonance is highly sensitive for TM polarization with oblique incident angles over 15 degrees. Besides the surface current, field and power loss density distributions, effective material parameters are analyzed to figure out the physical mechanism of absorption. Furthermore, the influences of absorption intensity and resonant frequency by changing the geometric dimensions of the structure and thickness of the dielectric substrate have also been discussed. The experimental results agree well with numerical simulations and this definite polarization (TM) insensitive absorber with super-close bands can be applied in high sensitivitivy/resolution absorption detectors, switchable absorption devices between dual and single band, and sensors with TE or TM EM waves under oblique incidence.