Soil permittivity estimation from TDR measurements: properties and guidelines

The properties of the TDR waveforms are studied by means of the Debye's permittivity equation and of a low-order model of the measurement setup. The study is aimed at obtaining guidelines useful for the estimation of the soil permittivity from TDR waveforms. The high frequency attenuation due to the propagation in the dielectric medium has a central role in deciding the shape of the TDR waveforms. High-frequency permittivity parameters are best estimated from waveforms produced by measurement system with low attenuation. The properties of waveforms also lead to simple relations to estimate the low and high frequency permittivity values from characteristic points of the waveforms.