An antenna system for estimating the direction of arrival (DOA) of signals, configured to provide both the azimuth of a signal that arrives from the horizon and the elevation of the signal below and above the horizon. The antenna system covers a 360° section.

A radar system for finding the direction of arrival of signals arriving from the horizon within an azimuth of 0-360° and elevation angles in the range of from -70 to 70 below or above the horizon, respectively.

An unmanned aerial vehicles (UAVs) aerial traffic monitoring system that comprises one or more UAVs, such as quadrocopters or drones, each bearing a transponder and at least one of a transmitter, a localization module and/or a communication module