Electromagnetic Scattering and Inverse Scattering of Layered Media with a Slightly Rough Surface

An electromagnetic (EM) scattering model for layered media covered by a 3D infinite rough surface and the corresponding inversion technique are investigated. The work aims at remote sensing the surface roughness and dielectric constant for different depths of bear soil through radar measurement data. The forward problem is carried out by the wave decomposition method. The small perturbation method (SPM) and EM boundary conditions are employed to solve the integral equations introduced by the wave decomposition method. The second-order SPM solution of the scattering field is involved in the computation of the forward problem for the first time. The backscattering coefficients of multiple frequencies, multiple angles and multiple polarizations are employed to create a nonlinear optimization problem. A genetic algorithm is introduced to help the inversion procedure approach to the global minimum of the cost function. Examples are carried out to validate the inversion technique. The inversion results show good agreement with the forward problem with given parameters and pose good tolerance to the input data with the additive white Gaussian noise.