Impact of Ground Parameters on Performances of an Active Phased Array Element of the Low-Frequency Radio Telescope GURT

Abstract

This paper presents the technique of numerical estimation of ground parameters impact on the performances of an active antenna used as an element of a phased array antenna of a modern low-frequency radio telescope. Three ground conditions were considered, two of them wet and dry, which correspond to the extreme values of seasonal deviations of its parameters, as well as its median state (“normal ground”). The results of computer simulation are given for the active antenna of the GURT radio telescope with a ground screen in the form of a square wire grid of [Formula: see text][Formula: see text]m and without it. It is shown that the addition of the ground screen markedly reduces the influence of the ground conditions on some parameters of the antenna, in particular, the dipole impedance and radiation efficiency. At the same time, the ground screen does not protect the most important antenna parameters for radio astronomy, such as sensitivity and absorption area, from the impact of the ground conditions changes. Variations of these parameters for an active antenna with a screen remain approximately the same as without it.