High-frequency scattering from a cylinder coated with a rarefied dielectric layer

An examination is presented of scattering from an infinitely long, perfectly conducting cylinder in which the cylinder is coated by a dielectric layer, the dielectric constant of which is less than that of the surrounding medium. Asymptotic formulas are developed for the high-frequency limit. There are three contributions to the scattered field: the geometrical optics contribution, the creeping wave, and a wave which travels in the dielectric layer. Detailed descriptions of the first two contributions have been given previously in the literature. The wave traveling in the coating is described in a way which makes calculation easier when the results are generalized to convex coated objects, the shapes of which do not permit an exact solution. The method described uses the concept of a fictitious source to simplify the calculations. The results are subject to the restriction that the difference in the dielectric constants is large, and the thickness of the coating is much less than the radius of the cylinder. It is shown that the method of description of the guided wave is in some sense complementary to previous work carried out in lateral wave propagation