Estimation of Medium Permittivity for Subsurface Radar Imaging Based on Conditional Entropy Metrics

In order to obtain a high resolution inverse synthetic aperture radar image, the kinematic parameters of the target must be estimated in order to focus the image. Entropy metrics have been a popular technique to achieve good estimates. For subsurface radar imagery, the parameter needed for focusing purposes is the permittivity of the medium. Unlike airborne radar, subsurface back scattering occurs in a noisy environment and the use of this traditional metric does not yield good results. In this paper, the authors proposed the use of a denoising technique and a conditional entropy metric that overcomes the difficulties encounter when using an entropy calculation as a focal quality indicator