The simple asymptotic analytical expressions of the electromagnetic fields induced by a vertical electric dipole on a perfect conductor coated with a dielectric layer have been obtained. These expressions show that the induced fields consist of the direct wave, reflected wave, lateral wave and trapped surface wave. The propagation wave number of the trapped surface wave is between that of the wave number k0 in the air and the wave number k1 in the dielectric. The amplitude of the trapped surface wave attenuates as ρ-1/2 in the ρ direction near the surface and attenuates exponentially as e-γz in the z direction. The expressions for the direct wave, reflected wave and lateral wave in this paper coincide with those given by King and Sandler <1994>. When the thickness of the dielectric layer is not small, the lateral wave and the trapped surface wave are combined the total field to produce an interference pattern.