Combination of Expanded Graphite/Fe/Fe₃O₄ Composites and Hollowed Out Chiral Metamaterials toward Ultrathin, Ultralight, Broadband, Polarization‐Insensitive, and Wide‐Angle Absorbers

Abstract

Abstract Achieving thin, light, broad, and strong absorption properties for traditional electromagnetic wave absorbers remains a big challenge. In the present study, an ultrathin, single‐layer hybrid absorber consisting of a periodic array of hollowed out chiral mosquito‐incense unit cells filled by expanded graphite(EG)/Fe/Fe 3 O 4 composites is proposed to drastically improve the integrated properties of traditional absorbers. The experiment verifies that absorption of the hybrid absorber remains higher than 90% at the frequency range of 21.4–36.3 GHz, which corresponds to the ultrathin thickness (0.5 mm), ultralight weight (0.83 kg m −2 ), and wide‐angle absorption (15°–60°). The equivalent LC circuit and current distribution are given to reveal that the superior properties stem from the synergistic effect of λ/4 resonances, multiple LC‐resonances, cross‐polarization, and cross‐coupling of the patterned structure. This finding demonstrates the potential for hybrid absorbers of ultra‐lightweight, ultrathin, broadband, polarization insensitive, and wide‐angle absorption to be used in millimeter wave devices.