An Improved form of the Spectral Iteration Technique

An iterative approach to the solution of the first kind integral equations arising in electromagnetic scattering problems is considered. The analysis is carried out in the spectral domain, where integral equations can be transformed into algebraic equations, suitable for easy manipulations on computers. The proposed iteration scheme assumes the static solution as initial estimate of the unknown current distribution on the scatterer. With this choice, the procedure is guaranteed not to diverge and the convergence is significantly enhanced. As a matter of fact, static solution enforces the correct edge behaviour solving the Electric Field Integral Equation (EFIE) with respect to the regular part of the current density. Diffraction by strips of both small and large dimensions (compared to the wavelength) is considered as illustrative example of the method. The procedure is applicable to more complex structures like printed circuits on stratified dielectric support, where the Green's function is known in the spectral domain.