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Abstract
A K-space technique that has proven successful for analyzing acoustic fields is applied to electromagnetic fields in the very near reactive region. In cylindrical coordinates the K- space spectrum describes helical wave modes on a fixed radius cylindrical surface that represent either propagating and evanescent mode energy. When this surface encloses a radiating or scattering object the resulting K-space decomposition reveals information about the physics of the wave-object interaction. Originally applied to the scalar wave equations of acoustics this method has been adapted to the vector wave equations encountered in electromagnetics. Here, the K-space decomposition is applied to the near electric and magnetic fields generated by a plane wave scattered from a perfectly conducting, finite length cylinder. We numerically simulate electromagnetic fields scattered from cylinders with a smooth surface and a surface with periodic grooves to illustrate the ability of the K-space method to differentiate between propagating and evanescent modal energy. Features in the K-space spectrum that impact the far field bi-static scattering cross section are identified to provide the link between the near field analysis and far field cross section.