Dielectric Measurements and Automatic Control of Materials Heated Inside Microwave Ovens

Preliminary results obtained on an apparatus and a method for non-contact measurements on the dielectric properties of materials heated inside operating microwave ovens, are presented. Variations in the dielectric constant and the dielectric losses of a variety of materials (food, rubber, textiles, minerals, etc.) are measured inside a modified Toshiba 600 microwave oven. The temperature range of measurements varies from freezing temperatures to temperatures exceeding 1600°C. This new technique can be used to provide reliable heat controls on microwave ovens. In addition, such measurements can provide a better understanding of the dielectric-temperature dynamic processes involved when heating materials inside microwave ovens.