Influence of a thin inhomogeneous surface layer on electromagnetic ground wave propagation

A theory is outlined for propagation of electromagnetic waves over a conducting half-space which is coated by a thin inhomogeneous layer. The source is a vertical electric dipole. An asymptotic development indicates that the conventional ground wave formulas are applicable if the surface impedance parameter is defined in a more general manner. An exampie indicates that a lossy half-space with a nonabrupt boundary has effects akin to a dielectric-coated homogeneous half-space.