Polarisation-insensitive and wide-angle multi-layer metamaterial absorber with variable bandwidths

Three different metamaterial absorbers based on ultra-thin multi-layer structures, with different bandwidth characteristics, are presented. The proposed structure is composed of three vertically stacked metal-dielectric layers backed by a metal ground. All the metallic patches are of crossed dipole shape and have different geometrical dimensions, which can be manipulated to design triple-band, 3 dB and 10 dB absorbers separately. The designed structures are polarisation-insensitive as well as wide-angle absorptive for both TE and TM polarisations. The 10 dB broadband structure, exhibiting an absorption bandwidth of 7.5% at 10 GHz, has been fabricated and the absorption performance has been verified with the simulated response. The proposed absorber has the advantages of ultra-thin thickness (λ₀/50 corresponding to the centre frequency), compact size, simpler design, tunable absorption bandwidth and experimental validation, which makes it a promising candidate for many potential applications.