Dielectric liquids behavior by Time Domain Reflectometry (TDR)

The time domain reflectometry is a relatively recent technique which in general allows impedance measurement of a coaxial air line portion filled with the device under test (DUT). Basically the system is a closed circuit RADAR implying an incidental step pulse and its feedback that is a time reflected signal. When the studied material is dielectric matter, most of its electric properties are contained in the considered signal whose shape rightly depends then on two principal parameters, the permittivity and the conductivity. The materials that we chose to characterize by this method are firstly a series of alcohols well-known and secondly some ionic solutions with distilled water and domestic salt. We present for the ionic solutions, the reflected temporal signals obtained using a digital sampling oscilloscope Tektronix 11802. For the series of alcohols we present the modelling temporal reflected signals from their dielectric parameters in frequency domain.