AN IMPROVED CIRCUIT THEORY OF A MULTIELEMENT ANTENNA

An integral equation for a multielement antenna having finite gaps at the driving points is derived. An approximation of this equation is calculated on the assumption that the gap capacities are negligible as is the case with ordinary antennas, and it is used to explain the stationary property of the input impedance. If the electric current distribution is expressed by the sum of a number of trial functions, the equation for determining the coefficients of the functions is found from this condition for the stationary properties. This equation is an improvement of the circuit equation for antennas written in terms of self and mutual impedances defined by the EMF method. The mutual impedance is affected by all antenna elements. The trial functions for the electric current distribution must be smooth near the driving points and must be approximately constant within the gap. Numerical calculations on a circular array consisting of five full-wavelength cylindrical antenna elements are shown to verify the usefulness of the improved theory. Copyright © 1969 by The Institute of Electrical and Electronices Engineering, Inc.