Electromagnetic Parameters Of The Test System

The development of an electromagnetic parameters (including relative complex permittivity and complex permeability) test system was studied in this paper. According to the demand of this study and the available equipment, the coaxial transmission/reflection method was chosen as measurement method. Based on the traditional NRW transmission/reflection algorithm, a new refined algorithm was presented. According to the magnetic property of the material under test, the algorithm could get different solutions, then obtain the complex permittivity and complex permeability of magnetic material simultaneously or the complex permittivity of non-magnetic material. It solves the multi-roots problem and the half-wavelength divergence problem which exist in the traditional NRW algorithm and overcomes the machining and assembling problem of thin samples which is required in the traditional algorithm. Moreover, in order to remove the influence of the test fixture to the test results, the entire de-embedding technology was discussed. Besides, the E.M. simulation software HFSS was used to simulate the fixture and calculate its S-parameter as an experiment.According to the coaxial fixture and samples actually used, the calibration process, principles and some notes of the Vector Network Analyzer (VNA) HP 8720D were summarized and the most accurate calibration method, full 2-port calibration was carried out. The S-parameters were measured by the VNA; automatic test software was programmed to control the VNA and to realize the data collection, calculation, display and the saving modules. Therefore, the whole test system was established. Tests of air and PTFE were carried out to verify the reliability of this test system and the results were consistent with true values. The electromagnetic parameters test results using traditional algorithm and the refined algorithm were given separately and analyzed in detail. Finally, the test error of the entire test system was deducted and analyzed. In this process, Matlab was used to accomplish the error calculation.Besides, the influence of the common measurement errors including sample location and sample length was discussed concretely. The results demonstrate that the measurement error of d 1 which is the distance of the sample plane and the calibration plane gives little influence toεr′andεr′′; the measurement error of the sample length L shows relatively large effect toεr′, however it only does little withεr′′. The negative...