Effect of topography on SAR calibration

摘要

During normal SAR processing, a flat earth is assumed when performing radiometric corrections such as antenna pattern and scattering element size removal. Here we examine the effects of topographic variations on these corrections. Local slopes will cause the actual scattering element size to be different from that calculated using the flat earth assumption. It is shown that this effect, which is present for both airborne and spaceborne SAR data, may easily cause calibration errors on the order of a dB. In the case of airborne systems, the errors introduced by assuming a flat earth during antenna pattern removal are also significant; errors of several dB can easily result. The effect of topography on antenna pattern removal is expected to be negligible for spaceborne SARs.