Impact of Dielectric Coating on Scattering of Plane Electromagnetic Wave by a Metal Cylinder

Abstract

Impact of dielectric coating on electromagnetic wave scattering by a perfectly conducting objects was and still remains an issue of the day. In this paper, the problem is solved of plane electromagnetic wave diffraction on a perfectly conducting infinite cylinder with dielectric coating for the cases of E- and H-waves. The classic electrodynamic solution was used in computations that allowed obtaining the spatial distribution of fields in a dielectric layer and comparing it with the estimated scattered field far away from a cylinder at the backscatter and direct bearings. In order to identify the relation between the characteristics of the scattered field in the far field and its structure in the dielectric layer, in this solution the calculations were made for different ratios between wavelength and dielectric layer thickness. It is shown that appearance of characteristic “bunches” or “steps-like variations” in the reflected field is associated with field resonances within the dielectric layer, since wave scattering depends on the distribution of secondary sources in this layer. Whereas fine structure of “bunches” (rapid changes with frequency) arises from alterations in the azimuthal distribution of secondary sources both in dielectric and on the cylinder surface. It is shown that a dielectric coating cannot make a metallic cylinder invisible in the whole microwave band.