Nondestructive and mass‐independent moisture content measurements are necessary for the quality control of wheat flours. Methods that use microwaves can evaluate the moisture content on both the surface layer and the inside of the bulk of the wheat flour. We describe the correlation between amplitude change at the resonance frequency and phase change at a specified frequency for varying masses of wheat flour, using a cylindrical cavity resonator operating at 3.920 GHz. Three types of wheat flours with moisture contents of 9.6, 13.2, and 16.6% were used up to 0.3 g in this experiment. The relation between the amplitude change at the resonance frequency and the phase change at the specified frequency was linear. The squares of the correlation coefficients of the linear approximation lines were both 0.999 for the three wheat flours. The three types of moisture contents were distinguished based on the difference in the slopes of the approximation lines. The validity of the experimental results was confirmed via calculations based on the S‐parameter in the transmission characteristics of a two‐port resonator. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

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振幅和相变的相关性在小麦粉质量无关的水分含量评估中的应用

对于小麦粉的质量控制，必须进行无损和质量无关的水分含量测量。使用微波的方法可以评估小麦粉表面层和内部的水分含量。我们使用工作在3.920 GHz的圆柱腔谐振器，描述了不同质量的小麦粉在谐振频率处的振幅变化与在指定频率处的相位变化之间的关系。在本实验中，使用三种水分含量分别为9.6、13.2和16.6％的小麦粉。谐振频率处的幅度变化与指定频率处的相位变化之间的关系是线性的。三种小麦粉的线性近似线的相关系数的平方均为0.999。根据近似线的斜率的差异区分了三种水分含量。通过基于S参数的两端口谐振器传输特性的计算，证实了实验结果的有效性。©2020日本电气工程师学会。由Wiley Periodicals LLC发布。