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Synthetic-aperture radar (SAR) is a form of radar that is used to create two-dimensional images or three-dimensional reconstructions of objects, such as landscapes. [1] SAR uses the motion of the radar antenna over a target region to provide finer spatial resolution than conventional stationary beam-scanning radars.
Furthermore, aperture thinning reduces the overall volume and mass of the antenna system. A disadvantage is the reduction of radiometric sensitivity (or increase in rms noise) of the image due to a decrease in signal-to-noise ratio for each measurement compared to a filled aperture. Pixel averaging is required for good radiometric sensitivity.
The history of synthetic-aperture radar begins in 1951, with the invention of the technology by mathematician Carl A. Wiley, and its development in the following decade. Initially developed for military use, the technology has since been applied in the field of planetary science .
The United States launched two Future Imagery Architecture (FIA) radar satellites into 122° inclined retrograde orbits in 2010 and 2012. The use of a retrograde orbit suggest that these satellites use synthetic aperture radar. [3] Earth-observing satellites may also be launched into a Sun-synchronous orbit, which is slightly retrograde. [8]
Space-based radar or spaceborne radar is a radar operating in outer space; orbiting radar is a radar in orbit and Earth orbiting radar is a radar in geocentric orbit. A number of Earth-observing satellites , such as RADARSAT , have employed synthetic aperture radar (SAR) to obtain terrain and land-cover information about the Earth .
Called synthetic aperture radar (SAR), an ordinary-sized antenna fixed to the side of an aircraft is used with highly complex signal processing to give an image that would otherwise require a much larger, scanning antenna; thus, the name synthetic aperture. As each pulse is emitted, it is radiated over a lateral band onto the terrain.
The associated resolution loss from sharing the synthetic aperture among different swaths is compensated by collecting radar echoes with multiple displaced azimuth apertures. A possible drawback of multichannel ScanSAR or TOPS approaches is the rather high Doppler centroid, [ 9 ] which is one of the most important parameters need to be ...
The Advanced Synthetic Aperture Radar System-2 (ASARS-2) is the radar system mounted on some variants of the Lockheed U-2 reconnaissance aircraft.. The ASARS-2 radar was originally developed in the early 1980s by Hughes Aircraft, which was acquired by Raytheon in the late 1990s.