Electromagnetic characteristics and 3D-printing realization of a lightweight hierarchical wave-absorbing metastructure for low-frequency broadband absorption

Electromagnetic absorbing metastructure with low frequency and broadband absorbing capacity is desirable for scientific community and real-life application. Here, we designed a lightweight hierarchical wave-absorbing metastructure by replacing the facets of the stepped structure with smaller-scale square grid. The electromagnetic characteristics of high-efficiency absorption in low and high frequency ranges were also studied. The specific dielectric constant and dielectric loss were found to be the key factors of low-frequency absorption, which was realized by regulating the proportion of Ag-Cu alloy-based composite material based on fused deposition modeling 3D printing technology. The hierarchical gradient design for the wave-absorbing metastructure is helpful to not only being lightweight but also enhancing the electromagnetic wave absorbing capacity. The existing heterogeneous interfaces of flaky alloy particles and spheric polymer particles also enhance the dielectric properties of composite material. The fabricated wave-absorbing metastructure sample with the bulk density of 0.5 g/cm³ shows high-efficiency absorption in 2.5–40 GHz, and the absorbing performance keeps stable even though the incident angle varied in the range of 50°. This paper provides a convenient realization method of absorbing metastructure with low frequency broadband absorption performance, which has outstanding practical application value.