High Frequency Electromagnetic Shielding by Biochar-Based Composites

This work investigates the microwave shielding efficiency of non-structural composites, where inclusions of biochar—a cost effective and eco-friendly material derived from oil-seed—are dispersed in three different matrices of interest for building construction (i.e., epoxy resin, HDPE, Cement Portland Type 1 52.5 R). To this aim, the complex permittivity of raw materials and composites was directly measured in the frequency range 100 MHz–8 GHz, which allowed calculating the shielding efficiency (SE). This way it was possible to demonstrate that tailoring the content of biochar allows obtaining a desired value of electromagnetic shielding, potentially useful for different applications. This approach may help to design composites with desired shielding properties starting from physical parameters.