The UAPO Diffraction Contribution in the IPO Method for RCS Evaluations

A procedure improving the Iterative Physical Optics method is proposed to evaluate the radar cross section of large and complex targets with shadowing protrusions. The procedure accounts for the diffraction from the edge of a protuberance to increase the accuracy of the zeroth-order Physical Optics currents on the surface of the structure. The Uniform Asymptotic Physical Optics approach is suggested for this problem since it allows one to consider penetrable protuberances and protrusions with impedance or material coated surfaces. The corresponding solutions are approximate but they result from an analytic procedure. Moreover they are expressed in closed form and do not require computing special functions and integral equations.