Gigahertz Transverse Electromagnetic Wave Chamber Measurement And Calibration Method Research

As the development of the power electronic techniques, radiated electromagnetic interference (EMI) is generated by the application of high speed print circuit board and hasn’t yet been reduced without good measures. Radiated measuring devices provided by the electromagnetic compatibility (EMC) standards are mainly Open Area Test Site (OATS) and anechoic chambers, which civilian industrial products can’t afford. On the other hand, the low-cost device Gigahertz Transverse Electromagnetic cell (GTEM cell) is applied in Electromagnetic Susceptibility (EMS) test mostly. GTEM cell used in EMI measurement is still being studied which has low accuracy and complex implementations recently.In this paper, measurement and calibration methods of GTEM cell applied in radiated EMI were researched, including three parts:(1) Hardware structure and algorithms of radiated EMI measurement system for GTEM cell were proposed, which make it can be applied in both radiated EMI noise testing and diagnosis. And an automatic test system was designed by the software development platform Lab VIEW, which can convert the data measured by GTEM cell to an equivalent standard results and determine the radiated mechanism.(2) The calibration method was presented. a calibrated approach was proposed. Radiated noise was extracted by polynomial model of which the error was compensated based on variance analysis. Higher moments were employed to analyze the similarity of the radiated E-field measured by the calibrated GTEM cell and the3-m anechoic chamber.(3) Radiated EMI noises generated by voltage-driven PCB, RFID based credit card machine and visual aid for medical use were analyzed by GTEM cell according to the suggest methods above. It proved that the calibration of GTEM cell effective for different EUTs.The theory and experiment results show that GTEM cell can be applied in measurement and diagnosis of radiated EMI by employed the suggest method. And the accuracy was significantly improved which verified the calibration method effectiveness.