SAR Synthetic Aperture RadarSheet 1 of 18 SAR Synthetic Aperture Radar Why use microwave frequencies? - atmospheric attenuation is low at microwave frequencies,particularly 1-10GHz,apart from resonances due to oxygen and water molecules. - microwave signals will penetrate cloud and fog,in contrast to visible radiation. - microwaves can continuously monitor ploar regions and tropical forests that are often in darkness or covered in clouds. - SAR is to be used to monitor natural disasters -floods,forest fires,earthquakes etc that are often accompanied by poor optical visibility. - fairly narrow beams can be obtained with resonably sized antennas to give acceptable resolution. Features of SAR - a large effective antenna aperture is obtained by mounting the antenna on a moving platform-an aircraft or a satellite. - reso……