Random wave methods for the prediction of the RCS of homogeneous chaotic straight ducts

It is now fairly well established that convergence of shooting-and-bouncing ray methods is not feasible for the determination of the radar cross-section (RCS) of most realistic engine ducts. This is a consequence of classical chaos theory which was not recognised by radar engineers until quite recently (Mackay, 1998). However, at the time no solution to the problem was offered. A random wave method is described for the determination of representative RCS distributions of chaotic straight ducts, under two assumptions: first, that there is local field homogeneity, and secondly, that a Kirchhoff approximation is valid. Typical duct field magnitudes are illustrated for a stadium cross-section duct and the RCS is predicted as a function of scatter angle. A comparison is also made with an accurate modal solution