Research On Electric-field Probe Calibration System For 20Hz-100MHz

As a very important instrument of the electromagnetic environment measurements, electric-field probes act a very major role in the evaluation of electric-field strength of electromagnetic environment and electronic and electrical products. The calibration demands of the test instrument constantly increasing. National Institute of Metrology P.R. China is constantly improving the calibration ability of itself. It devoted much in the research of electric-field probe calibration system. And the research on electric field probe calibration system for 20Hz-100MHz is one of the most important parts.In this thesis, the composition of the electric-field probe calibration system for 20Hz-100MHz and the device features were introduced, especially about the structural characteristics, electrical characteristics and frequency limitations of the field generator TEM cell. The calculation method of the power and field strength in the center of the TEM cell had been researched. The calculation error of the power had been analyzed. The computational formula of the correction factor had been found. The longitudinal field distribution and cross-sectional field uniformity and the change of the field distribution after put the probe into the TEM cell had been analyzed by comparing the simulation result and the measured result. From the simulation result and the measured result, it can be seen that the field uniformity around the walls of the TEM cell is worse, and the center of the TEM cell is better, and there is a slight effect on the field distribution of the TEM cell after put the probe in.The main uncertainty factors of the probe calibration using the calibration system had been found through experiment test. Based on the experimental data, the relative standard uncertainty of each uncertainty factors had been calculated, then the relative combined standard uncertainty and the relative expanded uncertainty of the probe calibration had been calculated. Besides, the automatic test software system had been developed based on LabVIEW platform. And the design thought of the automatic test software and the design flow of each module had been introduced in detail.This system can be used to calibrate the electric-field probe for 20Hz-100MHz and the magnetic-field probe for 100kHz-100MH. And it increased the ability of the National Institute of Metrology P.R. China for the calibration of electric-field probe. Besides, the use of the automatic test software offsets the deficiency of manual-testing, and improves the degree of automation and testing efficiency.