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

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.<>