Permittivity measurements and effective medium approximation considerations

In this paper we show experimental results that rebate the validity of measuring the permittivity of partially saturated sands as an effective property. Experiments on twola, yer samples (one fully saturated and the other one with residual water saturation) demonstrate that an averaged water saturation is not a good representation of those samples, but must be modelled as two distinct layers, even when the wavelength is one or two orders of magnitude bigger than the height of these layers. We also show how to accurately determine the width of the fully saturated layer. This technique can be used to monitor the movement of a fluid front flowing through a porous media.