Resonant cavity structural design of carbon-based intrinsic metamaterial absorbers for broadening the effective absorption bandwidth

[Display omitted] •Structural-functional integration: We fabricated an intrinsic metamaterial by blending carbon-based absorbing agents and polydimethylsiloxane.•Enhanced absorption performance: A double-layer resonant cavity and ring current design broadened the effective absorption bandwidth.•Multi-scale electromagnetic loss: The metamaterial demonstrated loss at macro, micro, and nano scales, enabling advanced broadband absorption. The effective absorption bandwidth (EAB) of absorptive materials has always been a bottleneck limiting their applications. Particularly, the combination of macroscopic structural design and the loss functions at the microscopic level of materials provides an efficient solution to this issue. Herein, a novel approach was proposed, integrating macroscopic structural design with microscopic loss functions to broaden the effective absorption bandwidth (EAB) through designing an intrinsic metamaterial absorber composed of a uniform blend of carbon-based absorbing materials and polydimethylsiloxane. A key innovation lies in the dual cubic resonant cavity design, where the multiple dimensions of the resonant cavities enable the absorber to achieve effective impedance matching across a wide frequency range. Additionally, the generation of a bottom ring current induces a magnetic field, which enhances the metamaterial absorber’s capability for further attenuation of electromagnetic wave energy. These innovative designs enable traditional carbon-based absorbing materials to achieve exceptional absorption performance, with the EAB being 2.37 times that of the skin structure, addressing the narrow EAB issue of traditional carbon-based absorptive materials. Experimental results demonstrate that the prepared samples achieve an absorption rate of 90 % for electromagnetic waves in the frequency range of 5.74–18 GHz under normal incidence, consistent with the simulation results. This absorber boasts advantages of broadband, with an equivalent thickness of only 2.94 mm. Its structure is easy to manufacture, demonstrating certain potential applications, and providing valuable insights for the work of other researchers.