Yes, completely sure. Corner reflectors are used to calibrate SARs by providing fixed bright ground points. I've also seen SAR imagery where unintentional corner reflectors (in this case, a building) completely washed out the image at that location.
It's true that the SAR antenna has moved a little bit by the time the transmitted signal is received. However, the signal is moving significantly faster than the satellite - with a 600km orbit, velocity is ~8km/s - so the roundtrip time is maybe 0.04s, meaning the satellite has moved 320m. That's about 0.2 degrees from the point of view of the reflector.
The synthetic aperture is not just the distance covered in the round trip of a single chirp, but the distance covered during the imaging process. A SAR typically produces chirps constantly (in the tens to hundreds of Hz) and digitises the responses. All of the energy of all those responses can then be combined to form the image.
If the corner reflector is in a fixed location, every chirp will have a spike in the response corresponding to that location.
It's true that the SAR antenna has moved a little bit by the time the transmitted signal is received. However, the signal is moving significantly faster than the satellite - with a 600km orbit, velocity is ~8km/s - so the roundtrip time is maybe 0.04s, meaning the satellite has moved 320m. That's about 0.2 degrees from the point of view of the reflector.
The synthetic aperture is not just the distance covered in the round trip of a single chirp, but the distance covered during the imaging process. A SAR typically produces chirps constantly (in the tens to hundreds of Hz) and digitises the responses. All of the energy of all those responses can then be combined to form the image.
If the corner reflector is in a fixed location, every chirp will have a spike in the response corresponding to that location.