Open Microwave Cavity High Temperature Medium Parameters (temperature) Automatic Measurement System

In this paper high temperature dielectric open resonator measurement technique is mainly researched. Based on the technique, a high temperature automatic open resonator measuring system at Ku band is designed. This system controls the scalar network analyzer measuring with sweeping frequency method by a computer and adopts heating device to change the temperature of the sample. After getting the resonance frequency and Q factor of the vacancy and loaded cavity, the system works out the dielectric parameter and loss tangent of the material being tested.First, this paper briefs the microwave open resonator basic theory and its application. It particular introduces the scalar beam-wave theory and briefly introduces the complex source-point theory of the microwave open resonator. Secondly, gives the theoretical analyses to Q factor of microwave open resonator due to the mirror loss, mirror diffraction loss and coupling aperture loss in detail and obtains the more precise formulae for calculating Q factor. Third, an asymmetrical typed open resonator at Ku band is designed and the traditional method of measuring Q factor of the vacancy cavity is improved. Finally, it introduces the structure of the high temperature automatic measurement system at Ku band, dielectric measuring method and testing process. This system adopts PID arithmetic to control the heating device. The highest temperature of the dielectric above 1000℃. By using computer GPIB interface and microwave sweeping frequency techniques, the system achieves high temperature automatic measurement of low-loss radome dielectric and works with convenience and high speed. From the measuring results, this system shows high accuracy on measuring low-loss radome materials. It offers advanced measuring instrument for high temperature measurement of radome materials.