UC Berkeley

Most modern electromagnetic devices consist of dielectric and magnetic particulate composites, which are designed with specific properties for delivering optimal performance. Predicting the effective electric permittivity and effective magnetic permeability of the envisioned composite is of great importance in validating the design for such applications. Analytical bounds to estimate these effective properties can be found in literature. However, they often yield large solution ranges and do not account for the microstructure of the composite. We present here a numerical method to estimate these effective electromagnetic properties for any given composite microstructure. It consists of solving Maxwell’s equations numerically using a particular Finite Difference Time Domain (FTDT) method, known as Yee’s scheme, over a representative volume element of the composite of interest. It allows capturing its electromagnetic response, and subsequently computing its effective electromagnetic properties. Results obtained with this method show good agreement with analytical bounds and experimental data. We also observe more accurate estimations than analytical bounds. The method is then used to assess thermal influence on these effective electromagnetic properties. A numerical design tool, that combines the optimization technique known as genetic algorithm with the proposed numerical method for estimating effective electromagnetic properties, is also presented. It allows determining the required composition and microstructure parameters for a particle doped composite in order to achieve the desired effective electromagnetic properties.