Measurement of the frequency-dependent dielectric constant of concrete materials by TDR and wavelet modeling method

Time-domain reflectometry has been widely used in the measurement of material electromagnetic properties. In order to obtain the spectrum of the dielectric constant, the measured waveforms need to be analyzed by FFT. Because of multi-reflections in the measured waveform, it is sometimes difficult to extract a clear reflection for analysis and the final results may not be accurate. A wavelet modeling method was used in this paper to extract the frequency-dependent dielectric constant in the measured time-domain waveform. By transforming the measured signal into a series of frequency bands and recognizing it according to the composition of reflections, this method can reduce the effect of multi-reflections on the measurement results.