Rapid heating of dielectric materials at 915 mc

THE HEATING of dielectric materials by means of microwave energy was investigated in the General Electric Company a decade ago by members of the Research Laboratory, who demonstrated the feasibility of preheating plastics and heating foods using a magnetron oscillator at a frequency of 1,000 mc (megacycles). In recent years the GL-6787 magnetron, operating in the 915-mc Industrial-Scientific-Medical band, has been developed as a source of power for these applications. In quantity production, this tube will provide economical microwave power for consumer and industrial applications. In order to design equipment for efficient preheating, it is necessary to know the characteristics of the materials as a function of temperature. This paper presents the results of an initial investigation of the effectiveness of 915-mc heating on various dielectric materials, and describes means of measuring the characteristics of materials at this frequency.