High frequency analysis of interior wedge/horn scatterings

Summary form only given. Many scattering objects contain concave elements with planar facets where the incident wave undergoes multiple reflections. The number of multiple reflections increases in inverse proportion to the internal angle between facets and becomes very large for small wedge angles. This makes the solution of the scattering problem difficult. We study this problem for an appropriate model, shaped like the capital letter Z, which consists of junctions of three planar faces (two half-planes joined by a strip). Actually, such a geometry can be considered as an interior wedge/horn structure. A comprehensive analysis of multiple reflections inside this structure is presented. All possible horn shapes which create beams reflected directly back to the monostatic radar are identified. Radiation of the last reflected beams from the horn is studied in the Kirchhoff-Kottler and physical optics approximations. The Kirchhoff-Kottler approximation does not take into account the transverse diffusion of the wave field in the region between the reflecting faces and the radiating aperture. This phenomenon is described by the physical optics. Numerical data for the radiated field illustrate the effect of transverse diffusion. The field radiated by the reflected beams is only a part of the total scattered field. Edge waves radiated by nonuniform (fringe) currents represent additional contributions. They are studied in the framework of the physical theory of diffraction. A version of this theory based on a modified definition of nonuniform currents near the interior edge is developed. It allows the simplification of the scattered field computation.