Implementation of physical theory of diffraction for radar cross section calculations

A computer program which uses the Physical Theory of Diffraction (PTD) method to calculate the Radar Cross Section (RCS) of perfectly conducting targets with arbitrary shape is developed. Given an arbitrary surface, it is first meshed using planar triangles. The area of each triangle is restricted to be smaller than 0.005λ 2 in order to obtain a good approximation to the actual surface. After meshing, Physical Optics (PO) surface integral is numerically evaluated over the whole surface. If the surface has edges or wedges, diffractions originating from these edges play a significant role in the overall scattered field. This part of the diffracted field is calculated using PTD-EEC method. Calculation of the edge currents is made possible by canonically modelling the arbitrary-shaped edge. If the surface of the scatterer has thin wires attached to it, then the thin wire scattering formulation in the literature is applied. Expressions for scattering mechanism on a straight wire are based on diffraction, attachment, reflection and launch. The results get sufficiently accurate especially for electrically large bodies.