Improved Sample Holder for Q-Meter Dielectric Measurements

Anew sample holder is described for use with a Q-Meter to measure the dielectric properties of materials. It includes provision for controlling the temperature of the dielectric sample. It also is equipped with two cali-brated, variable air capacitorsone for measurements to determine the dielectric constant, and the other for measurements that determine the loss tangent. The im-proved design eliminates possible errors in determining the loss tangent, loss factor, and conductivity that can be caused by residual and lead inductance at the higher frequencies. Results of measurements between 10 and 40 MHz on samples of hard red winter wheat of different moisture contents are presented and discussed. Mea-sured values of the dielectric constant of wheat were somewhat dependent upon electrode spacing, because kernel dimensions were appreciable in relation to inter-electrode distances.