Method-of-moments analysis of electrically large circular-loop antennas: Nonuniform currents

A method-of-moments analysis is carried out so as to obtain, in closed form, the nonuniform current distributions, and their resulted radiation patterns in both near and far zones, of circular loop antennas with electrically larger circumferences. An oblique incident field in its general form is considered in the formulation of the nonuniform current distributions. In Galerkin's method-of-moments analysis, the Fourier cosine series is considered as the full-domain basis-function series. As a result, the current distributions along the circular loops are expressed analytically in terms of the azimuth angle for various diameters of large loops. Finally, the radiated electromagnetic (EM) fields and their power pattern in both near and far zones are determined by applying the dyadic Green's function (DGF) in spherical co-ordinates and plotted using a commercial software package, respectively.