A Broadband Wide-Angle Metasurface Absorber for Energy Harvesting Applications

A broadband electromagnetic metasurface (MS) absorber with a wide-angle coverage is designed and discussed for energy harvesting applications. The proposed MS absorber consists of two split-ring resonators (SRR) forming an X-shaped in the middle and layout is designed on FR4 dielectric substrate. An air gap layer is separated between the dielectric substrate and a ground plane. At normal incidence, the proposed MS structure achieves a higher absorption ratio (>90%) with a 10-dB impedance bandwidth of more than 4 GHz (2.14 GHz-6.4 GHz). For oblique incidence, greater than 85% absorptivity is observed from $0^{\circ}, to 30^{\circ}$ across the frequencies range from 2.14 GHz to 6.4 GHz. Two higher absorption peaks of more than 80% at 2.4 GHz and from 5 GHz to 6.5 GHz for TEM polarization are achieved respectively at 45° and 60°. Furthermore, the absorption mechanism is numerically demonstrated in detail.