Accurate tools for convergence prediction of series solutions of Contrast Source Integral Equations

Source Type Integral Equations (STIEs) provide interesting alternative formulations for the scattering from dielectric objects. In particular, the underlying operators factor into the composition product of two other linear operators, whose norms can be separately evaluated with the aid of suitable universal diagrams. Then, a specific inequality suggests that the convergence of the formal Neumann series inverting the original integral equation can be established by means of the aforementioned tools. Anyway, such an inequality sometimes provides pessimistic (i.e. stronger than actually needed) conditions in many cases of practical interest. The previous observation motivated the authors to further investigations, so leading to sharper bounds on the relevant norm of the STIEs operators. Numerical examples are reported, confirming the usefulness of the new tools.