Entire-domain polynomial approximation of volume currents in the analysis of dielectric scatterers

A method is proposed for the analysis of electrically medium-sized scatterers made of inhomogeneous, imperfect dielectric. The scatterer is modelled by parallelepipeds of arbitrary shapes and sizes, that can be positioned and interconnected arbitrarily, which enables efficient approximation of very diverse scatterer shapes. The current-density vector is approximated by entire-domain three-dimensional polynomials of arbitrary degree with complex coefficients within individual parallelepipeds, even if the dielectric inside them is continuously inhomogeneous. The coefficients are determined by the point-matching solution of the integral equation for the total current-density vector inside the scatterer. Agreement between the results obtained by the proposed method and those from other sources is found to be excellent, both in the far-field and current distribution. When compared with other available methods, however, the proposed method requires much less unknowns per λ_{in diel}³, although it is neither conceptually nor computationally more complicated than any of them