Electromagnetic Field of a Horizontal Infinitely Long Wire Over the Dielectric-Coated Earth

The simple analytical formula for the electromagnetic field radiated by a horizontal infinitely long wire over the planar surface of the earth coated with a dielectric layer is derived. It is concluded that the total field includes four modes: the direct wave, the ideal reflected wave or image wave, the lateral wave, and the trapped surface wave. In particular, both the trapped surface wave and the lateral wave are examined in detail. From analysis and computations, it is demonstrated the trapped surface wave, which is determined by the sum of residues of the poles, can be excited efficiently. When both the infinitely long wire and the observation point are on or near the planar surface, the trapped surface wave is dominant.