Field of a circular loop over a permeable lossy half-space

Abstract

The radiation field of a circular loop carrying an electric current and located horizontally above a permeable lossy half-space is formulated using the dyadic Green's functions. The resulting field vectors are split into the primary and secondary components. The primary components represent those that would exist in the absence of the half-space, leaving the secondary ones to represent the contribution of the half-space. The variation of the magnetic field on the loop axis is shown as a function of frequency and for a typical dry earth with a conductivity of sigma =10/sup -3/ s/m and mu /sub r/=1. The primary fields computed using the dyadic Green's functions and the closed form expression for a circular loop are presented to indicate the solution accuracy. The effect of the earth conductivity on the results is examined. The case of a permeable half-space is also studied. The results indicate that the secondary field components become significant only at high frequencies or when the ground conductivity becomes excessively large. Thus, in remote-sensing applications of buried objects, located in the vicinity of the earth interface, the ground effect can be neglected without affecting significantly the object's response. >