Wave Propagation in Cylindrically Stratified Dielectric Media and Application to RCS Characterization

An asymptotic model for the evaluation of the back-scattered field from a dielectric-coated cylinder is presented. The method is applied at aspect angles near broadside incidence, a region where the generated creeping wave (CW) has maximum intensity. Monostatic radar cross section (RCS) calculated from CW poles of the scattered field and their residues is validated with azimuthal CW contributions to the total scattered field computed by the method of moments (MoM). The state space spectral estimation algorithm is used to extract the CWs from MoM data. Meticulous calculations reveal unambiguous contrast between dielectric-coated objects and uncoated, bare metallic configuration. Because of smaller leakage induced by curvature on a coated cylinder in contrast to the metallic cylinder, and coherent interaction between incident wave and the dielectric coating, CWs, which are strongly attenuated by metallic objects, gradually evolve to trapped modes guided inside the dielectric layer for coated objects. With the increase in frequency, the wave trapping becomes more pronounced, and ultimately results in leaky waves with very little tangential ray shedding.