Reducing clutter in airborne radars equipped with electronically scanned array antennas

An airborne radar´s antenna beam pattern interacts with the terrain beneath the platform to create unwanted clutter returns. A novel display format for depicting this interaction was used to identify fundamental differences between traditional, mechanically scanned antennas and contemporary active electronically scanned array (AESA) antennas. It was observed that the elevation sidelobes of an AESA are deflected away from the vertical when the antenna´s mainbeam is steered electronically in azimuth; this can reduce the clutter caused by the altitude line. A technique is then proposed for reducing the clutter within the system by exploiting this phenomenon of deflected elevation sidelobes and the theory is supported with results from flight trials.