Synthetic Aperture Radar (SAR)

"A high-resolution ground-mapping technique that effectively synthesizes a large receiving antenna by processing the phase of the reflected radar return. The along-track resolution is obtained by timing the radar return (time gating) as for ordinary radar. The crosstrack (azimuthal) resolution is obtained by processing the Doppler phase of the radar return. The cross-track dimension of the antenna is a function of the length of time over which the Doppler phase is collected." (National Aeronautics and Space Administration, 2014)

Sources

"Synthetic Aperture Radar (SAR)". NASA Glenn Research Center, National Aeronautics and Space Administration. Last modified June 12, 2014.
https://www.grc.nasa.gov/www/k-12/TRC/laefs/laefs_s.html#SAR.
Accessed February 1, 2019.