A broadband metamaterial wave absorber based on carbonyl iron powder modified dielectric layer

In the field of broadband metamaterial absorbers, most research efforts have focused on optimizing the resonant layers and designing multi-layer structures, with relatively little attention paid to the dielectric layers themselves. This paper proposes a method of modifying the dielectric layer using carbonyl iron powder, which significantly enhances the electromagnetic wave attenuation capability of the dielectric layer in the X-band for metamaterial absorber. A broadband absorber capable of effectively absorbing electromagnetic waves (RL≤-10dB) over the frequency range of 4.92-18GHz, covering the C, X, and Ku bands, was designed. We analyzed the surface current distribution, power loss distribution, etc. to elucidate the absorption mechanism of the absorber. It was found that the modified dielectric layer accounted for more than 50% of the total loss in the 2-18GHz frequency band, and the effective absorption bandwidth was almost twice that of the unmodified dielectric layer, attributed to the introduction of a new electromagnetic wave loss mechanism by carbonyl iron powder. Meanwhile, the absorber exhibited good angular stability, maintaining at least 80% absorption (RL ≤ -7 dB) in the 6.0-18.0 GHz range even when the incident angle was increased to 60°. The experimental results show that the measured results match the simulation results well, and compared with other methods for broadening the absorption bandwidth, the metamaterial absorber obtained by this method offers several advantages, including wideband absorption, thin profile, and a simple manufacturing process. This approach provides a new and promising direction for the design of broadband absorbers.