Inverse scattering of two-dimensional dielectric objects buried in a lossyearth using the distorted born iterative method

An efficient inverse-scattering algorithm is developed to reconstruct both the permittivity and conductivity profiles of two-dimensional (2-D) dielect ric objects buried in a lossy earth using the distorted Born iterative meth od (DBIM), In this algorithm, the measurement data are collected on (or ove r) the air-earth interface for multiple transmitter and receiver locations at single frequency. The nonlinearity due to the multiple scattering of pix els to pixels, and pixels to the air-earth interface has been taken into ac count in the iterative minimization scheme. At each iteration, a conjugate gradient (CG) method is chosen to solve the linearized problem, which takes the calling number of the forward solver to a minimum. To reduce the CPU t ime, the forward solver for buried dielectric objects is implemented by the CG method and fast Fourier transform (FFT), Numerous numerical examples ar e given to show the convergence, stability, and error tolerance of the algo rithm.