【摘要】 短形诸振腔，工作于TE（105）和TE（107）模式，中心频率分别为4．55和5．80GHz；当大小和湿度不同的生物体（黄豆或玉米粒）置于谐振腔中心时，谐振频率和品质因数发生变化。对频偏（ΔF）和传输因子（ΔT）的测量，发现它们与颗粒的含水量及干燥质量之间有重要的统计相关关系，可以用这两个测量的腔参量来表示湿度。通过“曲线拟合法”进一步获得简单的湿度近似表达式，且与颗粒的形状无关。应用这些谐振腔测量技术，测定形状近似球形的黄豆粒的7～16％范围内的湿度，其不确定性小于1％，可信度达95％以上。对于大小悬殊，形状很不均匀的玉米粒，把它们固定在腔中央、相对于腔内最大电场矢量互差90度的两个位置上，对ΔF和ΔT分别作两次测量，发现它们的平均值实际上与形状无关。这样，上述方法也能确定任意形状的玉米颗粒的湿度，不确定性仅为1％左右。更多还原

【Abstract】 A C-band rectangular waveguide cavity operating in the TE105 and TE107 modes at 4. 55and 5. 80GHz, respectively, is used in determining the chang in resonant freguency and the Q-factor ofthe cavity caused by single soybean seeds or corn kernels of various dimensions and different hydrtionlevels,located in the center of the cavity. Significant statistital correlations are found between measuredparameters and the amount of water in the seeds or kernels and their dry mass. Moisture contenl, being aratio of these two masses, may, therefore, be expressed in terms of two measured cavity parameters,regardles of the mass and shape of nearly spherical seed. An empirical approach consists of relating theratio of these two parameters with the seed moisture content by a curve fitting metthe. With thesetechniques, the mosture content of soybeans in the range from 7 to 16 percent can be determined with anuncertainty lower than 1 percent at the 95 percent confidence level.By measdring there two parametere, ΔF and ΔT, for a highly nonuniform corn kernel oriented intwo opitions differing by 90 degrees with respect to the maximum E-field vector, the averag values ofΔF and ΔT are found to be virtually shape-indeopdent. Thus, techniques mentioned above may alsodetermine moisture contents in arbitrdrily shaped corn kernels with an uncertainty of about 1 percent.更多还原