Ultrathin hybrid absorber based on high-order metamaterial

In this work, we utilized a hybrid resonator to achieve near-perfect and dual-band absorption in the VHF and the LTE/Bluetooth/WiMAX bands. An electromagnetic (EM) wave at an oblique incidence was captured efficiently by exciting the fundamental magnetic resonances at 106 and 123.4 MHz. In particular, the effective thickness of the metamaterial perfect absorber (in comparison with the working wavelength $\lambda$) is miniaturized to be $\approx 0.03\lambda$ at the high-order resonances (induced in the 2.0–4.0 GHz range) at a specific incident angle of EM wave, $\theta$ = 45°, 30°, 15° and $\theta$ = 5°. Our results contribute to the realization of meta-devices, such as sensors, optical filters/switchers, photodetectors, and energy converters, for future applications in the radio to the microwave frequency bands. (paper)