radarSAR

RadarSAR, short for radar synthetic aperture radar, is a radar imaging system that uses the motion of the sensor to simulate a large antenna, producing high-resolution images of the Earth's surface. It transmits microwave energy and records the backscattered signal. Because the sensor remains active, images can be captured day or night and through clouds or rain.

In operation, a SAR platform (aircraft or satellite) moves along a fixed look direction while emitting pulses. The received echoes are processed to resolve range (across-track) and azimuth (along-track) dimensions. The motion creates a synthetic aperture, enabling finer angular resolution than a physical antenna would allow. The data can be formed as single-look or multilook images; coherent processing preserves phase, enabling interferometric SAR (InSAR) for height and surface deformation measurements and polarimetric SAR (PolSAR) for scattering mechanism analysis.

Applications include mapping and topography, land cover classification, forestry and agriculture, geology, flood and disaster monitoring, ice and ocean studies, and urban change detection. Interferometric techniques provide digital elevation models and monitoring of ground movement, while polarimetric techniques aid material and structure characterization.

Common platforms include spaceborne missions such as ERS, Envisat, RADARSAT, TerraSAR-X, and Sentinel-1, as well as airborne SAR systems. Limitations include speckle noise, processing complexity, geometric distortions in rugged terrain such as layover and shadow, and large data volumes. RadarSAR remains a fundamental technology for all-weather, day/night remote sensing and earth observation.