SAR (Synthetic Aperture Radar)

Synthetic Aperture Radar (SAR) is a form of radar imaging that achieves high spatial resolution by exploiting the satellite's motion along its orbit to synthesise a much larger effective antenna aperture than the physical antenna. The satellite transmits microwave pulses toward the ground and records the reflected echoes, then computationally combines signals received at successive positions to form an image. Because SAR uses its own illumination (active sensing) at microwave frequencies, it can image through clouds, rain, smoke, and darkness — unlike optical sensors. SAR is used for maritime surveillance, ice monitoring, deforestation detection, urban mapping, disaster response, and interferometric terrain measurement. Major SAR missions include Sentinel-1 (ESA), RADARSAT (Canada), and Capella Space (commercial).