The mode matching technique for electromagnetic scattering by cylindrical waveguides with canonical terminations

The problem of scattering by open ended cavities is important in EM analysis because jet engine inlets are significant contributors to the radar cross-section (RCS) of aircraft configurations. Numerous studies have been published relating to the scattering analysis of ducts with rectangular and cylindrical cross-sections. Although these methods have been quite successful in modeling simple, large geometries, they are not suited for characterizing ray reflections from complex jet engine terminations which have irregular boundaries and edges. With this in mind, the motivation in the paper is to present methods for the characterization of irregular engine-like terminations placed at the back end of the duct. Specifically, the mode matching (MM) procedure is applied to two different cavity terminations, namely an array of straight and curved blades. The challenge in the latter case is the expansion of the fields propagating within the array of curved grooves and an analytical solution to this problem is given for the first time.