What is SAR Imagery? A Complete Guide to Synthetic Aperture Radar. A type of radar technology called Synthetic Aperture Radar (SAR) produces finely detailed, high-resolution pictures of the Earth's surface. SAR actively sends microwave signals toward the ground rather than depending on sunlight, then records the reflected signals to create images. The phrase "synthetic aperture" refers to the way SAR systems combine radar data gathered throughout the flight path of the satellite (or aircraft) to