Abstract
A method is proposed for using the Maxwell–Garnett formula to calculate the dielectric permittivity of composite materials made of metallic nanoparticles of arbitrary shape distributed randomly on a dielectric substrate. The error in approximating the reflection and transmission spectra of test structures by the original and modified Maxwell–Garnett theory is analyzed and compared with finite-difference time-domain (FDTD) calculations. The proposed approach can be used to model metamaterials with negative and near-zero effective dielectric permittivities. This method is used to calculate the effective permittivity of experimental samples containing silver nanoparticles with nonuniform shape and size distributions.