Enhancing and broadening absorption properties of frequency selective surfaces absorbers using FeCoB-based thin film

Abstract

In this paper, the influence of FeCoB-based magnetic film on the absorption properties of traditional frequency selective surface (FSS) was investigated experimentally. A single-layer Minkowski fractal planar frequency selective surface was chosen, and the laser etching technique was proposed to fabricate aluminum-based FSS (AFSS) samples. Magnetic films were prepared by radio frequency magnetron sputtering, with the targets of Fe₄₀Co₄₀B₂₀ and SiO₂. It is found that after the magnetic film is incorporated, the bandwidth under −10 dB increases by 33.3% from 5.08 to 6.78 GHz and the peak value of reflectivity decreases from −12.46 to −38.41 dB. The 3.1-mm-thick radar absorber is relatively light and could obtain the reflectivity of −38.41 with −20 dB bandwidth of 1.85 GHz. As a consequence, under the circumstance that the total thickness of the sample maintains relatively constant, the magnetic thin film can effectively improve the absorption properties of the sample.