Microwave properties of PVC-based composite films with yttrium iron garnet and carbon fillers

Thin poly(vinyl chloride)-based composite films containing 20 wt.% Y3Fe5O12 and 10 wt.% carbon filler exhibit a pronounced filler-dependent electromagnetic response in the Ka-band. Activated carbon, MWCNTs, graphene nanoplatelets, carbon nanoparticles, and carbon black were characterized by SEM and TGA. The composites were analyzed by FTIR spectroscopy and electrical measurements. The measured S11 and S21 values reach −10.8 and −8.6 dB, respectively, with absorption up to 48%. The MWCNT-filled film exhibits the highest attenuation, consistent with its substantially enhanced electrical connectivity. The results demonstrate that carbon-filler type strongly influences reflection, transmission, and microwave energy dissipation in thin composite films.