Using Physical Optics shadow radiation to improve shadowing in Iterative Physical Optics

Predicting aircraft ducts Radar Cross Section (RCS) is an interesting challenge. In order to calculate electromagnetic scattering in such open-ended cavities, several methods have been developed: some rigorous methods, and some asymptotic ones. Iterative Physical Optics (IPO) is an asymptotic method based on Physical Optics (PO), which has shown good results. This paper shows an improvement of IPO method for calculation of electromagnetic scattering by cavities, by using a physical approach (and not a geometrical technique as in classical PO method) to take into account shadowing effects. The method, called physical shadowing, is based on using shadow radiation (around forward direction) with PO approximation in the magnetic field integral equation applied to two coupled objects.