The travel time analysis of the time domain reflectometry (TDR) wave form gives one single value for the apparent dielectric permittivity, while it is frequency dependent. In this research Fourier Analysis was used to obtain the frequency dependend permittivity from the TDR-signal as measured with a seven rod probe. Inverse modelling of the TDR wave form was used to obtain directly the parameters of the Debye relaxation model, which is used to model the frequency dependence of the permittivity. In the frequency range between 0 and 1.5 GHz the accuracy and reproducibility in different alcohol＇s and sacharide solutions were examined The results were compared with standard measurements carried out with a network analyser (NWA) with open end probe, as well as measurements carried out with the NWA following the inverse modelling technique and using the seven rod probe. Without any calibration the inverse modelling method gives good trends for all parameters, while for the static dielectric permittivity the absolute values are accurate within 20%. The results of NWA and TDR compare very well.