Measurement of water content profiles by single TDR experiments

A new inverse procedure for the interpretation of TDR traces is introduced. It is based on the numerical integration of the differential equations of the transmission lines. By minimising the integral difference between the numerically simulated traces and the experimental ones, the distribution of the electric properties along the probe can be obtained. In particular, the profile of the relative dielectric permittivity leads to the water content distribution along the probe. In order to test the validity of the proposed method, a series of experiments were carried out. The inverse procedure was used in order to reconstruct the relative dielectric permittivity profile of layered media with known dielectric characteristics, in which a TDR probe was inserted. In all cases the agreement between the predicted and the real distributions was satisfactory.