Design, fabrication and characterisation of scaled and stacked layers planar metamaterial absorber

In this study, various forms of design, simulation and measurements of a new type of metamaterial absorber (MA) is investigated at X band. In the first step, an ultra-thin absorber is considered with absorptivity of 99% at frequency 9.88 GHz. The thickness of the structure is only 1/120 of the radiation wavelength. In the second step, a multi-layered structure is designed by stacking several layers of the design on top of one another. For the three-layered structure, two absorption peaks appear at 10.17 GHz of 98% and 10.89 GHz of 99%, respectively. In the third step, resonant frequencies are placed near each other by exploiting the scaling property of the MAs. Unit cells with three scaled elements have the absorption peaks at three resonant frequencies of 9.26, 9.6 and 10.10 GHz with the absorptions of 100, 95 and 84%, respectively. Finally, scaled and stacked structures are combined. The absorption spectra of the three-layered scaling structure have four resonant frequencies at 9.32, 9.76, 10.35 and 11.21 GHz with the absorptivities of 99, 100, 97 and 83%, respectively, with a total full width at half maximum-bandwidth of 2260 MHz. Results of the recursive method and the simulations are in good agreement with those of the measurements.