Research On Compensation Algorithm In High Tem Perature And High Frequency Impedance Spectru M Measurement Using Coaxial Fixture

Based on the temperature and frequency characteristics of coaxial structure transmission lines,this paper solves the impedance measurement problem of solid sheet structure samples at high temperature and high frequency.The main object of study is the fixture of all-metal coaxial structure designed and processed by the research group independently,and the errors generated in the measurement process are analyzed.Under the condition of high temperature and high frequency,the sample impedance value at the end of the fixture is deduced by the analysis method of distributed parameters.Due to the influence of physical phenomena such as thermal expansion and cold contraction,multiple reflection,and electrical delay generated at high temperature and high frequency in the measurement process,compensation and correction calculation is proposed from the theoretical level,so as to improve the precision of impedance measurement of solid thin-flake samples.This paper carries out the research and analysis work with great innovative significance from the following aspects: measurement error compensation under high frequency conditions.When electromagnetic wave propagates at the interface of different media,due to the higher frequency and shorter wavelength,the reflection loss of electric field wave increases,and the skin depth decreases,so does the absorption loss.Therefore,there will be multiple reflections between the sample and the test fixture surface,resulting in the deviation of the measurement results.At the same time,when the thickness of the sheet sample becomes non-negligible compared with the wavelength of electromagnetic wave propagating in the sample,the measurement error will also become non-negligible due to the phase difference generated by the phenomenon of electrical delay.In addition,the capacitive structure formed by placing the tested sample needs to consider the edge effect,so the edge effect under the structure also needs to be considered.In the case of high temperature,this paper analyzes the structural changes caused by thermal expansion and cold contraction effects,and then obtains the parameters under the corresponding state,which is used to analyze the influence of high temperature on the fixture.After defining the physical phenomena that are affected by the results,the corresponding error compensation formulas are given respectively in this paper,and the error compensation algorithm is implemented in MATLAB environment.Second,in order to verify the validity of the algorithm,in the process of research using HFSS environment to rebuild the fixture structure,and in the process of simulation by changing placed in the electrical characteristics of the clamp custom samples and its thickness,resulting in overall(sample + jig)impedance spectrum characteristics of the changes in the affected by the above several physical phenomena.By comparing the real impedance of the custom sample with the modified impedance after simulation calculation,the error size can be obtained through comparison.After the use of error compensation algorithm,the measurement error can be greatly reduced.