Full-waveform inversion of GPR data in frequency-domain

A new full-waveform inversion scheme is developed to obtain high-resolution images of cross-hole ground penetrating radar (GPR) data. The inversion is formulated as a non-linear least squares problem which minimizes errors between synthetic and observed data. The full-waveform modeling is implemented in frequency domain using the finite-difference (FDFD) solution of Maxwell equation. Here, we are using an iterative gradient method (Gauss-Newton) where the gradient is determined by using the forward vector wavefield and the backward-propagated vectorial residual wavefield. The algorithm inverts sequentially from low to high frequencies and permittivity and conductivity distributions can be obtained simultaneously. Preliminary inversion results of a synthetic example for a homogeneous background model with embedded high contrast parameters anomalies show that the permittivity result is comparable with time domain full-waveform inversion that uses an expanding bandwidth for increasing iterations.