Impedance of a circular array of vertical dipoles above a lossy ground (in direction finding)

In direction finding, the amplitude and phase of the signal at the antenna element depend not only on the angle-of-arrival (AOA) of the incident wave but also on the input impedance of the element antenna, which in turn is determined by the array configuration, element location in the array, and beam scan angle. The effect of the lossy ground on the input impedance of the element antenna is significant. An appropriate correction must be applied in order to derive an approximation of the true value of the AOA. Using both the image principle and the method of moments, one can numerically solve the input impedance of each dipole of the array while beam scanning. The discrete image theory is shown to be efficient and to give accurate results when evaluating the effect of a lossy ground. Numerical results are presented on a circular array consisting of 16 half-wave dipoles.<>