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

In this paper, a method of moments analysis is carried out so as to obtain in closed form the non-uniform current distributions, and their resulted radiation patterns in both the 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 non-uniform current distributions. In the Galerkin´s method of moment 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 the near and far zones are determined by applying the dyadic Green´s function (DGF) in spherical coordinates and plotted with the Mathematica package, respectively.