Dielectric loss angel measurement algorithms based on DFT spectrum correction

It is well know that, in discrete Fourier transform(DFT) based waveform analysis of multifrequency signals, there will be great dielectric loss measurement error. In this paper, the spectrum leakage presented in details, the energy of the signals will transpire because of the frequency fluctuation which brings asynchronous sampling, and the energy correlation is not zero between different frequency points. On the basis, smoothing signals steep degrees by using cosine window, in order to improve phase correction on discrete spectrum, two different methods which adopt frequency offset to measure the signal phase on the maximum spectrum peak are presented. By MATLAB simulating, the results show that two methods are easily carried out with high accuracy and Practicality.