Traditional honeycomb-like structural electromagnetic (EM)-wave-absorbing materials have been widely used in various equipment as multifunctional materials. However, current EM-wave-absorbing materials are limited by narrow absorption bandwidths and incidence angles because of their anisotropic structural morphology. The work presented here proposes a novel EM-wave-absorbing metastructure with an isotropic morphology inspired by the gyroid microstructures seen in Parides sesostris butterfly wings. A matching redesign methodology between the material and subwavelength scale properties of the gyroid microstructure is proposed, inspired by the interaction mechanism between the microstructure and the material properties on the EM-wave-absorption performance of the prepared metastructure. The bioinspired metastructure is fabricated by additive manufacturing (AM) and subsequent coating through dipping processes, filled with dielectric lossy materials. Based on simulations and experiments, the metastructure designed in this work exhibits an ultrawide absorption bandwidth covering the frequency range of 2-40 GHz with a fractional bandwidth of 180% at normal incidence. Moreover, the metastructure has a stable frequency response when the incident angle is 60° under transverse electric (TE) and transverse magnetic (TM) polarization. Finally, the synergistic mechanism between the microstructure and the material is elucidated, which provides a new paradigm for the design of novel ultra-broadband EM-absorbing materials.
Keywords: additive manufacturing; bionic design; electromagnetic wave absorbers; gyroid structures; metastructures.
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