Top-Level Electromagnetic Design of Multishell Resonant Cavity for Microspherical Microwave Structural Absorbers

In response to the increasing need for high-performance microwave absorption materials (MAMs), this study introduces a multiaxis electrospinning method for synthesizing graphene-based aerogel microspheres (GAMs) aimed at broadband microwave absorption (MA). The micro/nanostructures and shell configurations of GAMs are effectively regulated and controlled to establish a predictable structure-properties relationship via establishing equivalent electromagnetic (EM) models. The computational simulations results of the structure–property relationship are employed as guidance to evaluate the effects of structural features, like hollow structures and multilayered shells. The analysis reveals that enhancing the hollow cavity optimizes impedance matching and promotes MA performance. Utilizing these insights, the fabricated hollow GAMs (HGAMs) achieve an effective absorption bandwidth (EAB) of 8.1 GHz and an optimal reflection loss of −34.8 dB at 3.3 mm thickness. Further simulations involving various hierarchical structures of GAMs arranged into mono/bilayer arrays investigate the group coupling effects on MA performance through the synergistically absorptive, interferential, and resonant attenuation mechanisms. Actual MA performance examination using an arch method on HGAM bilayer arrays confirms the simulations, achieving an EAB of 15 GHz at a thickness of 7 mm. Consequently, this approach demonstrates a promising avenue for developing lightweight, nanostructured MAMs suitable for advanced applications.