Uniform Asymptotic Solutions for Scattered Field by a Coated Conducting Cylinder

We derive two kinds of uniform asymptotic solutions for the high-frequency scattered field when a cylindrical wave is incident on a coated conducting cylinder covered by a thin lossy dielectric material. We show that the extended UTD (uniform geometrical theory of diffraction) solution and the modified UTD solution derived by retaining the higher order term can be applied uniformly in the transition region near the shadow boundary and in the deep shadow region in which the conventional UTD solution produces the substantial errors. The validity of the uniform asymptotic solutions derived here is confirmed by comparing with the exact solution obtained from the eigenfunction expansion.