A new procedure of point-matching method for calculating the absorption and scattering of lossy dielectric objects

A method of numerically calculating the electromagnetic scattering and absorption by dielectric objects of high aspect ratios and composite geometrics has been developed. The solution procedure is based on expanding the scattered and internal fields in terms of multiple spherical vector wave functions, using point-matching to satisfy the boundary conditions and the least-square method to solve the resulting system of equations. The unique feature of this technique is that it utilizes multiple spherical expansions to describe the fields both inside and outside the object. The various parameters used to examine the convergence of the solution are discussed; they include the number of subdomain expansions interior and exterior to the object, the number of terms in each expansion and the advantages of the least-square method of solution. The new method was found suitable for making calculations for objects with aspect ratios as high as nine, and even for objects with composite geometries, including a capped cylinder and an object that consists of a spherical and a prolate spheroidal section. Numerical results were compared with results based on volume integral equations and method of moments, and excellent agreement was found