Study On Microwave Parameters Measurement Of Dielectric Materials At High Temperature

The electromagnetic parameters and reflectance of microwave dielectric materials are the key indexes to evaluate their performance,which directly affect their application efficiency.The measurement of the index is also an important link in the research,production and application of microwave dielectric materials,with very important engineering application value,and microwave dielectric materials are often used in high temperature environment.therefore,it is necessary to develop a set of microwave dielectric materials can accurately test the electromagnetic parameters and reflectivity of room temperature to high temperature system.Aiming at the testing requirements of 8.2～18GHz,room-temperature ～1200 degree electromagnetic parameters and 1～40GHz,room-temperature ～1400 degree reflectance,a testing scheme based on rectangular waveguide transmission/reflection method to test electromagnetic parameters and bow method to test reflectance was proposed.According to the test program set up including high-temperature carbon fiber waveguide,fast heating and temperature control of the electromagnetic parameters of microwave heating furnace equipment testing subsystem,and the "T" type bow frame structures,reflectivity test subsystem of equipment,on both sides of the bow frame can be tested at room temperature and high temperature respectively,and through the arched position pulse,multiple Angle dynamic continuous testing can be performed.In order to accurately obtain the S parameters at both ends of the sample and calculate high-precision electromagnetic parameter test values,the electromagnetic parameter inversion algorithm,TRL calibration algorithm and de-embedding algorithm are derived.HFSS software is used to conduct modeling and simulation of the three algorithms,and the simulation results verify the practicability of the three algorithms.Several common samples were tested at room temperature and high temperature,the test error is basically less than 3%,the accuracy meets the requirements.In the test of high temperature reflectivity,the calibration method is analyzed first,and then in order to reduce the influence of the scattering along the furnace of high temperature furnace and improve the measurement accuracy of reflectivity,the RCS reduction structure based on the dihedral Angle is designed according to the calculation formula of the dihedral Angle RCS.After FEKO software modeling and simulation,it is concluded that the optimized structure in high frequency band can effectively reduce RCS.The reflectivity of 4 test plates at room temperature and high temperature was tested.The test errors were all within 2d B,and the repeatability was better than 0.5d B,which met the requirements of the index.At the same time,the test software including electromagnetic parameter test,reflectance test,data analysis and control of the bow frame is designed,and the parameters setting,data acquisition,data calibration,result analysis and control of the bow frame are realized.The test error of electromagnetic parameters is basically less than 3%.The results of dynamic reflectance test show that the reflectance will change if the test Angle is changed.