High-resolution radar in inhomogeneous media

The problem of radar imaging in inhomogeneous media is considered. Electromagnetic fields are calculated by approximating the wave equation using the finite difference time domain (FDTD) technique. The variance in the permittivity of the medium is assumed be low-pass Gaussian. The received echoes are calculated for various values of surface roughness and permittivity differences. The effects of an aberrating layer on radar imaging are also examined. The cross-correlation between the echo signals received at different channels are calculated. The effects of inhomogeneity of the medium on the cross-correlation coefficients and on the point spread functions (PSF) are analyzed. The PSF corresponding to the delay-and-sum SAR algorithm and the delay-and-weighted-sum algorithm are compared