An iterative method for computing the scattered electric fields at the apertures of large perfectly conducting cavities

The cavity problem, such as the electromagnetic scattering from a jet engine, may be visualized as consisting of three unique phenomenon: 1) an aperture field is established from the external region sources; 2) the electric and magnetic fields propagate down the cavity, "guided" by the cavity walls; 3) a reflection occurs at the termination. After reflection, the fields propagate back towards the aperture where they may be integrated to give the scattered field (i.e., the RCS). The purpose of this paper is to propose an efficient and accurate way of propagating the field from the aperture to the termination and back to the aperture. In the examples given, the termination is approximated as a short circuit. In an actual engine, the termination is very complex and must be accounted for by other methods such as the finite element method. In this paper we bypass the termination problem by employing the simplest of all possible terminations, the short circuit, since our objective here is to focus on the duct propagation problem.<>