小波建模法在混凝土材料介电常数时域测量中的应用研究

材料电磁参数的测量方法主要分为时域和频域两种。在时域测量时，需要通过FFT才能求得介电常数的频谱特性，而实际测得的波形往往存在多次反射，给求取一个纯净的反射波进行频谱分析带来不便。针对这一问题，提出了采用小波建模法对脉冲时域反射波形进行处理，给出了FFT法和小波建模法分别对模拟和实测波形处理结果的比较。结果显示小波建模法可以较好地区分时域反射波形中的反射信号，并能够从时域波形有效地提取介电常数随频率的变化规律。

Time -domain Measurement of Permittivity of ConcreteMaterials by Wavelet Modeling

In time domain measurement of the electromagnetic constants of materials, the measured waveforms need to be analyzed by FFT in order to obtain the spectrum of dielectric constant. The measured waveforms usually have multi reflections, which makes it difficult to extract a clear reflection waveform for analysis. A wavelet modeling method is proposed to analyze the time domain reflectometry waveforms. The simulated and measured waveforms are processed by FFT and wavelet modeling. Comparison of the results is made, which shows that wavelet modeling method can well distinguish the reflections in the measured waveforms and then extract the frequency dependent permittivity of the tested material.