Broadband microwave absorber based on patterned surface structure

The limitations of traditional flat microwave absorbers in terms of material parameters make it challenging to improve the working bandwidth. An artificial surface microwave absorber is one of the techniques used to increase the absorption band and the main goals of research in this field. The core–shell of Fe₃O₄ and polypyrrole in an epoxy resin matrix has been manufactured and then filmed as flat and artificial semispherical surface (ASS) thin films by a simple method. ASS films have been designed numerically and fabricated experimentally with a high-performance electromagnetic absorber. The peak absorption at 5.3 GHz and 7.7 GHz has values greater than − 40 dB simultaneously, rather than 99.9% absorption in the frequency range of 5–12 GHz, which has a thin thickness of 1.5 mm and has a weight less than the weight of the absorber flat with the same thickness. The numerical simulation of the absorption results indicates that the ratio of the radius of the semisphere patterns to the total thickness of the absorbent film is the most important factor. Apart from this, the absorption mechanism of the absorber has been determined. The superb absorption performance is realized through both the dissipation of the electromagnetic field by a highly absorbent material and the diffraction edge of waves throwing ASS at different frequencies. Our study provides a design to significantly increase the microwave absorption bandwidth with currently available materials.