What airspeed is recommended for best ISAR performance?

• A. Airspeed has no impact on ISAR performance
• B. Airspeed should be between 50 and 100 knots
• C. Airspeed should be between 0 and 200 knots
• D. Airspeed should be above 500 knots

Answer: (A)

ISAR imaging builds its synthetic aperture from the relative motion between the radar and the target, not from how fast the aircraft is flying. As long as you have accurate motion compensation and navigation data to correct for the platform’s own movement, the aircraft’s speed does not by itself change the amount of coherent phase information or the resulting image quality. The cross‑range resolution comes from the extent of the synthetic aperture created by the target’s changing aspect and the processing, not from airspeed. So with proper motion compensation and sufficient aspect coverage, airspeed has no impact on ISAR performance.