Integral equation method for scattering and absorption of electromagnetic radiation by thin lossy dielectric discs

Abstract

An integral equation for the current induced in a dielectric body by incident electromagnetic radiation is solved for the case of a thin flat circular disc of homogeneous lossy dielectric material. The equation is reduced by using the method of moments to a linear algebraic matrix equation for the coefficients in an expansion of the current density as a linear combination of basis functions. The matrix elements consist of integrals involving the basis functions. The novel computational aspects of this work lie in the choice of basis functions and in the techniques which this choice enabled to handle singularities in the integrands when evaluating the matrix elements, to reduce the matrix size and to rigorously preserve symmetries in the matrix. Expressions are given for the scattering and absorption cross sections in terms of the expansion coefficients. The results are most suitable in the resonance range of wavelengths when the disc radius and free-space wavelength are of the same order of magnitude.