GPR early-time signal features for the evaluation of shallow-soil permittivity

The possibility to retrieve an estimation of the real and imaginary parts of the soil permittivity by means of the recently-proposed Early Time Signal (ETS) technique is revised here. ETS is a potentially attractive approach for efficient non-destructive testing of shallow subsurface, making use of simple fixed bistatic configurations of usual Ground Penetrating Radar (GPR). In previous work, thanks to an accurate and versatile implementation of an electromagnetic CAD tool, the more revealing signal attributes that enable for predictable correlation to the ground permittivity values have been outlined, and relevant results have been quantified and discussed. Besides, experimental investigations on ad-hoc test sites through commercial GPR systems have also been developed as regards the effects both of the dielectric constant and of the conductivity of the ground media. The most significant pieces of information obtained in these testing cases will be reviewed here, and perspectives and criticalities for the practical application of this innovative approach will be highlighted.