Analysis of a Thin Circular Loop Antenna Over a Homogeneous Earth

In this paper, the current distribution on a bare conducting loop, situated in free space over a semi-infinite medium, is obtained for arbitrary time harmonic excitations. The loop is assumed to be thin, perfectly conducting and the standard one-dimensional integral equation and its Fourier series solution are used as the starting points. The field due to the current in the loop, where the semi-infinite medium is absent, is expressed as a superposition of plane waves. The tangential component of the field reflected by the interface, of the semi-infinite medium, is evaluated using appropriate Fresnel reflection coefficients. This reflected field serves as a new source for the loop and induces a current on the loop. The field due to the induced current is treated in the same manner, and this process is repeated indefinitely. The summation of the original current and all the induced currents gives the steady-state current on the loop.