▎ 摘　　要

High-sensitivity electrical properties measurement of composite materials using an interferometric near-field microwave technique is proposed in this paper. A one-port calibration model is developed to relate the measured transmission coefficient to the local properties of the material. To represent the probe-composite sample interaction, an electrical model based on lumped elements is developed. As a demonstration, the complex permittivity and conductivity of composite materials prepared with polyvinyl chloride and different concentrations of graphene are experimentally determined at 2.45 GHz. The obtained results show that the proposed technique is sensitive for the detection of small contrasts of permittivity and conductivity in the composite material. When the graphene concentration increases from 1% to 30%, the conductivity increases from 0.0061 s m(-1) to 0.056 s m(-1).