Designing lightweight honeycomb-structured CB/SiO2 composites for exceptional broadband microwave absorption through nanoscale and macrostructural optimization

Achieving broadband electromagnetic wave absorption remains a critical challenge in the field of microwave absorption (MA), particularly due to the difficulty in attaining optimal impedance matching across a wide frequency range. This study addresses this issue by employing rational component optimization and advanced macrostructural design strategies. Silicon-coated carbon black (CB/SiO₂) composites were synthesized via an improved sol-gel method, enabling precise modulation of electromagnetic parameters, impedance matching, and MA properties by controlling the content of tetraethyl orthosilicate (TEOS). This approach enhanced impedance matching and interface polarization, resulting in superior MA performance. Notably, the CB/SiO₂-0.5 composite achieved a minimum reflection loss (RL_min) of −63.03 dB at a thickness of 2.0 mm with a filler loading of 10 wt%. To further enhance broadband absorption, a macroscopic honeycomb-structured absorber based on CB/SiO₂-0.5 was designed using electromagnetic simulation software (CST). The resulting absorber demonstrated an exceptional maximum effective absorption bandwidth (EAB_max) of 12.048 GHz. Simulated S-parameters confirmed that the honeycomb structure significantly improved impedance matching across a broad frequency range compared to the CB/SiO₂ flat structure alone. This study not only establishes a scalable method for fabricating high-performance MA materials but also highlights the potential of electromagnetic simulations in optimizing absorber designs for broadband applications.