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Earth and Space Sciences · Glossary

What is Synthetic-aperture radar; radar backscatter?

Also known as: synthetic-aperture radar · radar backscatter

Definition 25.9 University Earth and Space Sciences — Year 3 · Chapter 25 — Remote Sensing and GIS

A synthetic-aperture radar (SAR) is a radar carried along a track that looks sideways, and that combines the echoes it records from the same point of the ground along a length of its track, keeping their phases, as if they had been received by one antenna as long as that length. The radar backscatter of a surface is the fraction of the power it receives that it sends back towards the antenna.

The geometry of a side-looking radar, in the plane perpendicular to its track. The beam lights a swath to one side of the nadir; a point of the ground is seen at the slant range R under the incidence angle , along the line of sight (LOS). Echoes are sorted by their delay across the track, in range, and by the phase history of the synthetic aperture along it, in azimuth.
The geometry of a side-looking radar, in the plane perpendicular to its track. The beam lights a swath to one side of the nadir; a point of the ground is seen at the slant range RR under the incidence angle θ\theta, along the line of sight (LOS). Echoes are sorted by their delay across the track, in range, and by the phase history of the synthetic aperture along it, in azimuth.
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