Abstract
In the current scenario, the foremost use of microwave absorbers, such as stealth applications and electromagnetic (EM) wave shielding, demands thin and broad bandwidth microwave absorber. In this paper, an attempt is made to fabricate a "cost-effective" composite material, which has good absorption properties, and furthermore, to reduce the coating thickness, the multi-layering approach has been adopted. Because of the excellent magneto-dielectric properties, Fe and Al metal powders were chosen. To see the effect of particle size over microwave absorption property of Fe-Al hybrid nano-composites, the composite was milled for 40 h with an interval of 5 h using the mechano-chemical route. The phase analysis, morphology, and magnetic studies have been carried out for prepared samples and correlated with EM wave properties. The permittivity and permeability values in the frequency range of 4-14 GHz were determined using coaxial reflection/transmission method, and reflection loss (RL) has also been computed. The broad bandwidth of 9.35 GHz (4.65-14 GHz) has been achieved for 40 h milled nano-composite (size ~40 nm) with a coating thickness of 3 mm. For the reduction in the coating thickness, the multi-layering approach has been applied, and an artificial neural network-based method has been proposed to predict each layer thickness and material sequence. The computed results of RL for two-layer absorber exhibit a reduction in the thickness from 3 to 1.96 mm.