[1] 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 k 0 in the air and the wave number k 1 in the dielectric. The amplitude of the trapped surface wave attenuates as r À1/2 in the r direction near the surface and attenuates exponentially as e Àgz 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.

New formulas for the components of the electromagnetic surface wave propagating along the boundary between sea water (Region 1) and a one-dimensionally anisotropic rock (Region 2) have been obtained. The conductivity of the rock is taken to be σx=σy=σT, σz=σL, where z is perpendicular to the boundary. Both σL and σT are constant. When σL=σT, the new formulas coincide with those of Wu and King [Radio Sci. 17, 521, 532 (1982); J. Appl. Phys. 54, 507 (1983)] for an isotropic medium. When σL≠σT, the lateral-wave part of the field is separated into two terms of which the first is of electric type with the wave number k2=kL, and the second is of magnetic type with k2=kT. The new formulas can be used to interpret recent measurements of the oceanic crust.

[1] The expressions of the electromagnetic field induced by a vertical electric dipole on the spherical conductor covered with a dielectric layer have been obtained. The calculation shows that the trapped surface wave may be efficiently excited by a vertical electric dipole on the surface of the dielectric layer when the thickness of the dielectric layer is larger than a certain value which depends on the operating frequency and the dielectric permittivity. This conclusion coincides with that of the field excited by a vertical electric dipole on the planar conductor covered with a dielectric layer.

In this paper, the current and simple analytical formulas of the electromagnetic field generated by a vertical dipole on the surface of dielectric-coated imperfect plane conductor are derived. Especially, the model equation of the trapped surface wave are given and the trapped wave and lateral wave are analyzed carefully. Finally computations and discussions are carried out in several different cases.

Abstract-In this paper, analytical formulas have been derived for the electromagnetic field generated by a horizontal electric dipole inside high lossy half-space coated with a dielectric layer. This problem is corresponding to the electromagnetic field generated by a horizontal antenna in a submarine under an ice layer, or the measurement of the conductivity of the oceanic lithosphere with a horizontal antenna as the source, and a layer of sediment on the sea floor. These formulas obtained for the electromagnetic field can be employed to calculated the total field including the lateral-wave term and the trapped-surfacewave term. Because the wave number of the trapped-surface-wave term is different from that of the lateral-wave term, the interference appears in the total field. Additionally, this paper has presented the approximative formulas for a thin dielectric layer, which can be used for the communication in low frequencies region.