Electromagnetic Wave Absorbing Material Based on Magnetic Microwires

In this paper, we present an experimental investigation related to an electromagnetic radiation absorber for a preselected frequency range between 5 and 20 Ghz. It consists in an absorbent sheet located such that, in the absorber use position, said electromagnetic radiation falls on the absorbent sheet. The absorbent sheet is made up of a dielectric material containing amorphous magnetic microwires of which magnetic permeability in the preselected frequency range has an imaginary part mu" which is at least 100 times greater than that of the corresponding real part mu'. The small wire diameter, compared to the skin depth, guarantees the full penetration of the electromagnetic fields inside the microwires. In order to elucidate the contribution of electrical resonance to the absorption, absorbent sheets of dielectric material containing copper microwires have been also characterized at high frequency.