The Design Of EMC Near-field Testing System And Effect Research Of Near-field Probe On Detected Field

With the development and improvement of electromagnetic compatibility disciplines and related industries,the problem of electromagnetic compatibility has attracted more and more attention of the country and the people.With the implementation of compulsory certification of electromagnetic compatibility,EMC measurement technology has been developed rapidly.At present the formal EMC radiated emission generally need to be completed in the anechoic chamber,but the design and construction of anechoic chamber is complex and expensive,so only the professional testing agencies and large enterprises have the ability to build the units.Enterprises need an instrument that can be used for daily measurement of the electromagnetic radiation.According to the analysis of the theory and measurement of electromagnetic radiation,this thesis designed a system for electromagnetic compatibility pre-testing.The design is composed of two parts primarily:hardware and software.The hardware builds a mechanical framework that is built to drive near-field probe.This mechanical framework is based on two groups of stepper motor and guide rail.Control circuit based on single-chip computer drives the two groups of stepper motor.Spectrum analyzer processes the results of near-field probe acquisition.The software that is designed by Lab VIEW has two main functions:one is to move the near-field probe freely by controlling the control circuit;the other is to control remote spectrometer,to save the results after measuring and to process the related data.We tested some sample and use Ansoft HFSS to do the simulation after the completion of this design.We can find that the measured results are consistent with the simulation after compared them.This thesis also made a simulation analysis to explore disturbance effect caused by near-field probe during which we mainly used the Ansoft HFSS.Firstly,we simulate d the PCB radiation model,electric field probe and magnetic field probe;then,we simulated the actual situation,tested the probe-included electromagnetic radiation and the probe-out electromagnetic radiation respectively.Finally,by using some software to simulate and calculate radiation according the working principle of the near-field probe,we made our conclusion.