Improved Spectral Iteration Technique for the Scattering from Metallic Cylinders

The use of the EFIE ( Electric-Field Integral Equation) static solution, incorporating the correct edge behaviour, as an initial estimate of the current distribution in an iterative scheme, is considered. The procedure for improving the initial form of the current density is developed by manipulating the integral equation in the Fourier transform domain, where the integral equation becomes an algebraic equation, suitable for easy manipulations on computers. Imposing the static solution of the current as first step in the iterative solution for the Freedholm integral equation of the first kind means to extract the singular part of the equation and consequently improve the convergence. Diffraction by strips, semi-infinite conducting wedges, equilater triangular and square cylinders are considered as illustrative examples of the method, which is valid in the entire frequency range, including also the resonance region. The procedure depicted with semplicity is applicable to more complex structures like printed circuits on stratified dielectric support, where the Green's function is known in the spectral domain.