A novel scaling procedure for deriving the solution to large-body scattering problems

The problem of deriving numerically-rigorous solutions of electromagnetic scattering from large bodies continues to pose an immense challenge, and despite the progress made with multipole and other fast methods for efficient generation and solution of the method of moment (MoM) matrices, there still appears to be room for innovative approaches to addressing the large-body problem. We present a novel extrapolation technique, which constructs the high frequency solution for a class of scatterers by extrapolating the results derived by using legacy codes at two or more lower frequencies, for which the problem size is still manageable in terms of memory size and CPU time. The extrapolation algorithm is based on a selective scaling of the individual travelling waves components of the current distribution on the surface of the scatterer, whose scaling properties with frequency depend upon the nature of the travelling wave. The solution for higher frequencies is derived by using simple operations such as stretching for the magnitude and linear extrapolation for the phase. In contrast to the asymptotic methods, the extrapolation procedure is accurate in both the transition and shadow regions, even at grazing incidence. The versatility and robustness of the technique is demonstrated in several examples of large scatterers, including those with slope discontinuities and edges, illuminated at grazing incidence.