Estimating the angle of a low-flying target using a spaced receiving antenna system

The problem of estimating the angles of arrival of closely located objects reflecting radar signals using a system of spaced receiving antennas is considered. The main purpose of the algorithm being developed is to use it to separate the useful and reflected signals from the ground when observing low–flying targets. The estimates obtained may be characterized by measurement ambiguity, which is supposed to be eliminated using data from the main radar that illuminates targets. The aim is based on the maximum likelihood method, to develop an algorithm for estimating the arrival angles of multiple reflectors in conditions where the location of receiving antennas may have an arbitrary appearance. An algorithm has been developed for estimating the angles of arrival of signals from various targets using several spaced receiving positions. The description of the algorithm and the methodology for obtaining it based on the maximum likelihood method is given. The results of numerical calculations of the angles of low-flying targets in the presence of a signal reflected from the earth's surface (the antipode signal) are presented. The presented results demonstrate the efficiency of the algorithm and the possibility of extracting a useful signal from low-flying targets at target elevation angles from 1.5...2 degrees and more. The developed algorithm can be used to reliably determine the angle of low-flying targets in conditions of strong reflections from the earth's surface.