Abstract
In this study, we propose a wide incident angle- and polarisation-insensitive metamaterial absorber covered with structures comprising a metallic flower shape layer, a dielectric layer and a metallic ground plane. The influences of the structural parameters on the absorptivity are investigated numerically. The proposed absorber exhibits polarisation insensitivity as the number of symmetric petals of a flower shape reaches as high as 4, 6 and 8. Particularly, the absorber based on 8 petals shows an absorptivity of above 90% for wide incident angles up to 70° under transverse electric and transverse magnetic polarisations. The physical mechanism of these observations is clarified by investigating the electric, power loss density and induced current distributions, which is also supported by the retrieved constitutive electromagnetic parameters. That is, the absorption phenomenon is considerably affected by magnetic resonance. By modifying the petals into hollow shapes, the absorber becomes effective in confining the magnetic resonance and can thus minimise the resonant frequency variation to 0.22% without affecting the absorption performance. In comparison with other reported metamaterial absorbers, our design shows considerable practical feasibility in terms of resonant frequency stability, wide incident angle and polarisation insensitivity, thereby making it suitable for various applications in microwave frequency region.
Highlights
Electromagnetic (EM) metamaterial (MM) is an artificial material engineered to possess exotic properties, such as negative refractive index, permittivity or permeability, as a result of its structure rather than of its chemical composition
In this study, we propose a wide incident angle- and polarisation-insensitive metamaterial absorber covered with structures comprising a metallic flower shape layer, a dielectric layer and a metallic ground plane
A simple design of a wide incident angle- and polarisationinsensitive Metamaterial absorber (MA) based on metallic flower shape and ground plane separated by a dielectric layer is proposed and investigated numerically
Summary
Electromagnetic (EM) metamaterial (MM) is an artificial material engineered to possess exotic properties, such as negative refractive index, permittivity or permeability, as a result of its structure rather than of its chemical composition. MAs with wide incident angle and polarisation insensitivity are preferred in practical applications, such as solar energy harvesting Some approaches, such as using symmetry structures, have been successfully. It was reported that the resonant frequency variation in the MAs with single band application caused by the change of a large incident angle depended on the number of folds of rotational symmetry.[31,32]. Alvarez et al proposed a six-fold rotational symmetry MA structure, which showed good polarisationand incident angle-insensitive performance and resonant frequency stability.[36]. Tuong et al proposed the flower-shaped microwave MA with four-fold made of 4 petals which can realize the high absorptivity and polarization insensitivity, its operating frequency was significantly varied with the changing of a wide incident angle.[38]. We investigate the physical mechanism of this absorption phenomenon
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