Multiscale Investigation of EMI Shielding Performance in Carbon Black-Reinforced Epoxy Composites

This study presents an integrated experimental and analytical investigation of the electromagnetic interference (EMI) shielding effectiveness of carbon black (CB)-reinforced epoxy composites. Composites were fabricated using a simple hand lay-up technique with CB filler contents ranging from 4 wt.% to 40 wt.%. Shielding effectiveness was evaluated in the X-band frequency range (8–12 GHz) using a calibrated Vector Network Analyzer (VNA), relevant to radar, satellite, and wireless communication applications. An analytical model based on classical electromagnetic wave theory was developed to predict total shielding by incorporating reflection, absorption, and multiple internal reflections. The model showed strong agreement with experimental results, confirming its validity for preliminary design assessments. Increasing CB content significantly enhanced shielding performance, reaching a maximum of 47.48 dB at 25 wt.%, comparable to lightweight metallic shields. Minor deviations between model and experiment underscored the importance of uniform filler dispersion. Overall, the findings demonstrate that CB/epoxy composites offer a lightweight, cost-effective, and efficient alternative to traditional metallic EMI shields, with both practical performance and predictive design capabilities.