The influence of surface curvature on high frequency RCS simulations

In order to treat high-frequency scattering from large and complex objects, numerous asymptotic simulation codes have been developed. Most of these codes apply a hybrid combination of geometrical optics (GO) and physical optics (PO) theory, which is often supplemented by edge corrections, e.g. the physical theory of diffraction (PTD). In recent work by Weinmann, F. (2006), a powerful and accurate simulation tool including these methods has been developed, which is able to treat scattering from arbitrary metallic objects. Further enhancements considering dielectric objects and the uniform theory of diffraction (UTD) have also been implemented. Based on this theory, the influence of surface curvature on the results of Radar Cross Section (RCS) simulations is studied in this paper. Generally, most asymptotic simulation methods are using a triangular, relatively coarse mesh of the object, which results in fast simulation times. However, if accuracy is important, certain limitations are expected due to the geometrical accuracy of the surface elements. For this purpose, simple targets with curved surfaces are studied with respect to different mesh element sizes. For comparison, simulations are performed with an analytical representation of the surface, which exactly describes the surface curvature. The results clearly show a convergence towards smaller element sizes but, however, not towards the result with the analytical description of the surface.