Airborne RADAR is an active imaging technology that operates in the microwave portion of the electromagnetic spectrum by emitting short pulses of microwave energy and recording the reflection from a given area on the ground. The resolution of a RADAR imaging system in the cross-track direction (i.e. perpendicular to the flight path) is determined by the pulse duration (shorter pulse = higher across-track resolution), while the resolution of the RADAR in the azimuth direction (parallel to flight direction) is determined by the length of the antenna aperture (i.e. longer aperture = higher azimuth resolution).