Design, synthesis, characterization and performance evaluation of multi-band perfect metamaterial absorber

This paper presents the design, synthesis, characterization, and performance evaluation of a metamaterial absorber having four distinct absorption peaks. The proposed absorber is based on the periodic array of the hexagonal closed rings and octa-star structure printed over the dielectric substrate. The dimensions of unit cell are optimized such that the absorption takes place at the distinct frequency near the Federal Communications Commission defined radar spectrum e.g. at 4.10, 6.15, 10.05, and 15.52GHz with the absorptivity of 0.98, 0.99, 0.99, and 0.99, respectively. The proposed structure is fabricated and the experimental result shows high absorptivity under transverse electric and magnetic polarization for the wide angle of incidence angles, which is in concurrence with the simulated results. The equivalent circuit model of the absorber has been developed sequentially for each of the structure. Furthermore, the complex refractive index of the metamaterial structure has been retrieved in order to have a detailed analysis, which supports the absorption phenomena at all the corresponding frequencies. The proposed metamaterial structure appears to be a potential candidate for absorber applications in the radar cross-section reduction, thermal detectors, and thermal imaging.