Transient Plane Wave Scattering from a Circular Cylinder Backed by a Slit-Coupled Coaxial Cavity

Abstract

Aperture coupling to enclosures with low interior losses can cause marked changes in the scattering characteristics of a target without perforation. The changes are attributable primarily to interior resonances. In a previous frequency domain study, a generally applicable self-consistent system format has been introduced for “observable-based” analytical modeling of the exterior-interior wave processes pertaining to cavity backed aperture geometries. The formulation has been applied there to plane-wave scattering from a slit-perforated thin perfectly conducting smooth convex, cylindrical shell with an interior perfectly conducting smooth convex cylindrical load, modeled externally via the ray fields of the geometrical theory of diffraction, internally via guided modes in the annular waveguide between the inner and outer boundaries, and coupled self-consistently by the slit. This study is extended here to short-pulse plane wave excitation. The various wave constituents are now distinguished by their different arrival and turn-on times. Alternative hybrid wavefront-resonance formulations are explored and are shown to furnish well convergent parametrizations of the physical observables in the scattered signal.