Abstract—In this paper, the electric voltage of a single-layer ho- mogeneous and anisotropic composite material has been calculated developing a mathematical model based on the diffusion equation. The proposed model has been developed assuming the minimum wavelength of the source much longer than the greatest dimen- sion of the analyzed structures and the charge relaxation time of the composite material smaller than any allowable rise time of the field source. The finite-difference time-domain method, based on an explicit scheme, has been used to solve the differential equa- tions and a scaling approach has been adopted to reduce computing time. The obtained results carried have been compared with those obtained simulating an equivalent electrical circuit network using SPICE. A good agreement between these two methods has been ob- served.