RCS predictions using wide-angle PE codes

The accurate modelling of scattering by objects that are large compared to the wavelength is an almost unsolvable problem, even with today´s powerful computers. Rigorous methods (finite elements, FD-TD, method of moments) are computationally expensive for even modest size objects (characteristic dimension of a few wavelengths). Asymptotic methods (GTD, physical optics) have difficulty combining elements, which they can treat accurately, into compound scatterers. The parabolic equation method (PE) has been successfully applied to two-dimensional scattering problems for scatterers of dimensions of up to one hundred wavelengths. All computations were performed on a Pentium PC and took a few minutes at most. The split-step Pade method has been incorporated into our model to exploit its wide-angle capabilities so that we can treat phenomena which involve large scattering angles (e.g. edge diffraction) accurately. To put things in perspective, an outline is given of the derivation of the PE starting from the wave equation. All propagation and scattering of electromagnetic waves are described by Maxwell´s equations. Only two-dimensional structures are treated