[p5a0u9l]

Consider a simple radar as capable of locating objects in 3D spherical coordinates- range, azimuth, and elevation. Radar is typically really good at measuring distance, but because of the physics of wavelengths and antennas, it needs a relatively huge aperture to achieve good angular resolution.

SAR technique create a virtual or synthetic antenna by imaging coherently over a path that draws out the synthetic aperture.

Of course, time continues as the the platform (satellite in this case) is moving. SAR then requires precise spatial/temporal awareness to combine the returns from the ground into a coherent image.

It is similar to long exposure in photography leading to seeing dim objects far away.

In both cases, if objects in the imaged scene are moving during the scanning period, they become blurred in the final result.