Abstract: Due to the asynchronous sampling of the signal,there will be spectrum leakage when using FFT to process the signal,resulting in the low measurement accuracy of FFT dielectric loss angle.In order to improve the measurement accuracy of dielectric loss angle,the side lobe characteristics of different window functions are analyzed.A new cosine window is constructed through the self-multiplication operation of Rife-Vincent (Ι) window,and an FFT dielectric loss angle measurement method based on improved Rife-Vincent (Ι) window is proposed.The new window function has better sidelobe characteristics than the traditional window function,and improves the suppression effect of spectrum leakage.The simulation results show that the measurement accuracy of using Rife-Vincent (Ι) self-multiplication window method is higher than that of using Hanning window and Blackman window method.

Key words: dielectric loss angle, fast Fourier transform, frequency spectrum leakage, Rife-Vincent (Ι) self-multiplication window