Influence of substrate on broadband microwave absorption of metamaterial absorbers composed of multi-scaled split cut wires

Multi-band or broadband power absorption has been obtained from multiple arrangements of split cut wires (SCWs) of different length on grounded dielectric substrate. Computational tools were used to model the interaction between electromagnetic waves and materials with the SCWs structure. The multi-resonance of SCWs is found to be greatly dependent on substrate materials (FR4, air). Insertion of an air layer at the bottom side of the ground plane has the effect of broadening the absorption band, due to the effect of increasing the dielectric resistance by increasing substrate thickness and by decreasing effective permittivity. For the multi-resonance structure of 13 SCWs, a broad bandwidth (6.3-7.6 GHz with respect to 80% absorbance) is predicted. The simulation result is in good agreement with experimental result measured by free space method.