Broadening the absorption bandwidth by novel series-parallel cross convex-concave structures

As a new type of molding technology, three dimensional (3D) printing can realize the manufacturing of devices with complex shapes. In the current study, 3D printed polymer-derived ceramics (PDCs), whose molecules are customizable and designable, were fabricated to achieve high-intensity broadband absorption performance of electromagnetic (EM) wave radiation. Based on improving the surface impedance matching characteristics, with the aim of optimizing the attenuation characteristics, cross convex/flat bilayer structures and cross concave/flat bilayer structures were fabricated, respectively. Remarkably, the former exhibited a minimum reflection coefficient (RC_min) of −58.97 dB at a thickness of 3 mm, and a broadband absorption of 4.0 GHz in X-band (8.2-12.4 GHz) at 3.4 mm. More significantly, we successfully combine the cross-convex structure with the cross-concave structure of PDCs-SiOC in the same as well as in different layers to obtain parallel and series structures respectively. It was found that the EM absorption performance of parallel structures was better than that of series structures, which is attributed to the stronger resonance between the parallel structures than between the series structures. The generation of dipole and interfacial polarization of PDCs-SiOC and the advancement of conductivity contribute to the increase of dielectric loss. Consequently, the PDCs-SiOC with multifarious structures are promising radar stealth absorbing materials in aerospace field.