Triple‐band metasurface absorber for RF energy harvesting applications

Energy harvesting is expected to be ubiquitous and essential to modern‐day life in the future. The limitations of ambient sources, such as thermal, mechanical, and solar, for energy harvesting can be overcome by RF energy harvesting for low‐power devices. With the help of perfect metasurface absorbers, an electromagnetic wave can be used as an ambient source for energy harvesting. In this paper, a simple polarization‐insensitive triple‐band perfect metasurface absorber is proposed for RF energy harvesting applications. The three‐layer (metal–dielectric–metal) meta‐atom of the designed metasurface consists of a cross‐shaped metal patch surrounded by slotted square‐shaped metallic patches and of 9 × 9 $9\times 9$ meta‐atoms. The absorber is typically developed in S‐ and C‐bands with resonant frequencies of 3.06, 3.9, and 5.97 GHz. The absorption is near unity which persists over a wide angle of incidence. The experimental results are in close agreement, within 2%, with the simulation results. The reliability of the proposed absorber has been determined for the RF energy harvesting applications, and a high harvesting efficiency of 94.4% and 84% has been observed at 3.07 and 5.97 GHz, respectively.