Design and analysis of multi-band polarization-insensitive annular ring metamaterial absorber

A design and simulation analysis of multi-band metamaterial absorber (MA) is discussed in this paper. The MA has a compact size of 9 mm × 9 mm × 1 mm and is designed using FR-4 substrate as a dielectric layer with a relative permittivity of 4.4. The FR-4 dielectric layer is sandwiched by the copper patch having three annular rings at the top, and a copper ground at the bottom. The proposed MA resonates at 6.548 GHz, 8.961 GHz, 18.119 GHz, and 18.442 GHz, i.e., at C band, X band, and K band having the maximum absorption rate of 99.07%, 98.44%, 99.95% and 99.62% respectively. At different polarization angles, the proposed structure exhibits polarization-insensitivity allowing near-unity absorption at the resonating frequencies. The structure also has a bandwidth from 17.93 GHz to 18.62 GHz at K band.