Analysis of a circular-loop antenna using moment methods

Abstract

The main objective of this paper is the determination of an approximate generalized solution to the current distributions of a circular-loop antenna using the method of moments. Numerical results obtained and displayed in graphical forms show that the maximum excursions of the current amplitudes occur when the azimuthal angle is 180°, while phase reversals of the current distributions that are symmetrical about the aforementioned value of the azimuthal angle occur when the electrical size of the loop antenna is greater than unity. Electric fields also computed exhibit sharp nulls for small values of the electrical size while these sharp nulls tend to disappear and the fields eventually degenerate into multiple lobes when the electrical size of the circular loop becomes relatively large. In addition, it is shown that when the loop dimensions are specified as 0-2 m and 0-5 cm for the loop and wire radii, respectively, the total power radiated by the loop exhibits its maximum value at a resonant frequency of 262-6 MHz. Other design parameters computed and whose characteristics are also presented include the radiation resistance, the directivity as well as the effective area and height of the circular-loop antenna. In all the computed results presented, an excitation voltage of 0-1 V is applied to the wire antenna structure.