Correction of the impact of refraction due to environmental conditions in high resolution SAR

SAR signal processing is based on the evolution of the time delay between the emission of the pulse and the reception of the echo during the illumination time. During processing, it is assumed that the wave travels through an homogeneous medium with constant dielectric characteristics and thus that the optical path corresponds to the straight line between sensor and target. In reality, waves travel through different media, like clouds, forest canopies, walls, which have a different dielectric constant. Refraction through those different media will impact the measured time delay and so lead to an incorrect estimation of the range of the different targets. Ignoring this effect during processing will cause a degradation of the image quality. It is possible to correct this effect when all parameters (thickness and dielectric constant) of the different media are well known. This paper proposes to analyze the possibilities to estimate the value of those parameters from the SAR data.