There are two types of imaging radar apertures: real (usually called RAR or SLAR for side-looking airborne radar or SLR for side-looking radar) and synthetic aperture radar (SAR). The SLAR imaging system uses a long antenna mounted on a platform. The synthetic aperture is used in space remote sensing applications. RAR is a radar system where the antenna beamwidth equals to the physical length of the antenna. It operates in a side-looking configuration, left or right with reference to the flight direction. It is an active, all-weather, day/night remote sensor onboar an airborne platform. Both Real Aperture and Synthetic Aperture Radar are side-looking systems having antennas aimed to the right or left of the flight path. The length of the antenna together with wavelenght determines the resolution in the azimuth direction, i.e. it is proportional to the distance to the object and inversely proportional to the length of the radar antenna.