Determination of the Mass of Cereals by the Use of Electromagnetic Fields

The experiments were carried out with a commercially available radio-frequency (RF) application device. It consists of three components: The generator, the applicator and the matching unit. The main function of the latter is that the unit is working without any power reflection to the generator after a short moment of calibration. At that moment the voltage between the capacitor plates U, load position AL and tune position AT are adjusted to different characteristics of the material in the applicator. The load and tune positions, AL and AT, are dimensionless specific parameters of the RF unit, which describe the status of the matching unit. Weighed samples were taken from winter wheat, or summer wheat, and filled in Teflon tubes. The mass of the samples varied between approximately 70 to 2700 g. Then the tubes were placed in the application chamber. Afterwards a defined power (250 W) was applied until no more power was reflected due to the described adjustment of the installation, which needed 5-15 s. Finally the parameters U, AL and AT were noted. The results indicated a close relationship between the parameters measured by the RF device on the one hand and the sample mass on the other. The R2 between the voltage between the capacitor plates and the mass of summer wheat amounted to 0.9996 (n = 150).