High resolution SAR performance limitation by the change of tropospheric refractivity

The imaging performance of high resolution airborne Synthetic Aperture Radar (SAR) system can be affected by phase errors resulted from the change in refractive index in the troposphere. Using the Hopfield model, we analyze the change in tropospheric refractivity, and give a calculation method for the apparent range between radar and a ground target. The mechanism in which the change in refractive index affects the high resolution airborne SAR performance is also analyzed. With a numerical calculation method, the maximum detection ranges of X-band and Ku-band SAR with different resolutions are obtained, and effects of the atmospheric refraction on the SAR image focusing are studied by simulations.