Measurement Of Complex Permittivity Of Dielectric Materials Under High And Low Temperature Condition

High-frequency PCB substrate was widely used in the microwave circuits and antenna design. Currently, our low-loss microwave PCB market is basically monopolized by Rogers, Arlon and the other foreign companies. Some domestic institutions are studying manufacture of low-loss and high-frequency PCB in order to break this situation. An important target of high-frequency PCB is the temperature coefficient of complex permittivity in the case of variable temperature, which is variation with temperature. The main work in this paper is provide a variable temperature complex permittivity test system for measuring the performance of low-loss high-frequency PCB based on strip line resonator method.First of all, this paper explains the basic theory of the strip line resonator method and verifies a key parameter which is impacted quality factor of low loss material strip line resonator namely surface resistivity in HFSS software, and the other parameters on the resonator frequency response, such as air coupling gap, metal surface roughness, probe size, closed cavity stray mode etc. Based on the above theory and simulation analysis, proposed the dielectric resonator method used of parallel plate for dielectric loss test problem of high-frequency low-loss PCB, and take a microwave surface resistance test under variable temperature conditions for strip line resonator metallic material, proposed a new amendments method for the measured complex permittivity based on the variable temperature test data.Then, build a microwave complex permittivity and the metal surface resistance test system under the variable temperature used low temperature cooling liquid circulation cooling and electric heating method, and take the complex permittivity test under the variable temperature for low-loss high-frequency PCB such as Rogers 6006. Obtained a more accurate dielectric loss data under the variable temperature through fixed surface resistance of metallic materials, the final test results showing a good agreement with reference data provided by Rogers.