Asymptotic computation of the RCS of low observable axisymmetric objects at high frequency

A method based on high-frequency asymptotic techniques is described for rapid radar cross section (RCS) computation for arbitrary convex axisymmetric objects whose geometry is described in a computer-aided design (CAD) format. A modified version of the physical theory of diffraction (PTD), which is free from divergence problems at caustics and shadow boundaries and yields good accuracy even for low-RCS objects, is employed. The spurious contributions due to sudden truncation of the physical optics (PO) currents on the shadow boundary, which yield nonphysical results, are removed, and the accuracy of the PTD is enhanced by adding the contributions due to the creeping waves and the fringe-wave currents for discontinuities in the curvature. This modified PTD yields results that are consistent with the geometrical theory of diffraction (GTD) when the stationary phase evaluation of the fields from the induced currents is valid, and also allows the RCS to be computed for the entire range of incidence angles. The results agree well with those computed with an integral equation code