An extended UTD analysis for RCS computations involving higher order curved surfaces

Abstract

The extended UTD (uniform geometrical theory of diffraction) analysis involves the use of spatial domain radiation integrals for the scattered fields. The relevant scattering mechanisms are then identified through uniform asymptotic evaluation procedures complemented with some rather heuristic modifications based on physical arguments. The typical scattering mechanisms involved are described by a new set of uniform reflection, first-order edge and zero-curvature diffraction coefficients that remain valid inside the transition regions and also reduce to the classic ray optical expressions in the exterior. In order to illustrate the accuracy of the extended UTD solution, numerical results are presented for a cubic polynomial strip and a superquadric cylinder. In both cases, the extended UTD result compares very well with the method of moments when the higher order mechanisms are not significant. The classic ray optical results, however, exhibit caustic singularities and discontinuities. >