| With the rapid development of the Chinese high-speed railway industry,the supporting communication infrastructure and technology have been at the forefront.The research and development of RF transmitter for communication infrastructure has also come to a new stage.Up to now,the requirements for RF transmitter can not only meet the realization of basic functions.The improvement of electromagnetic compatibility performance of equipment has gradually become an important reference index.Electromagnetic compatibility test(EMC)is an important basis to measure the EMC capability of equipment,and the test of radiation emission characteristics is the key and difficult point in the whole test.This thesis is based on the general requirements for electromagnetic compatibility of wireless communication equipment in national standards,and has referenced to a large number of domestic and foreign documents.Aiming at the electromagnetic compatibility problem existing in a certain train control equipment,a power amplifier module that conforms to the system performance is designed and implemented,and the electromagnetic compatibility performance simulation analysis and practical optimization are carried out.The thesis first completes the design and implementation of the power amplifier that meets the system functional requirements.Secondly,the radiation emission characteristics in the EMC performance of the designed power amplifier are modeled and simulated,and the optimization and improvement technologies are studied and analyzed.The radiation emission models of PCB boards and cables are established by using the circuit simulation software to predict the radiation emission characteristics of the circuit,and the simulation results are verified by using the near-field probe in the laboratory environment;Then the radiation emission test of the designed power amplifier was carried out in the anechoic chamber.It was found that the harmonic component was too high.For this problem,the second harmonic component was still high after the improvement of basic shielding and filtering.Finally,aiming at the problem of high harmonic component,a harmonic suppression circuit based on signal cancellation principle is designed and implemented..The test results show that the power amplifier designed and implemented in this thesis conforms to the GB/T24338.5 radiation emission standard of the national signal and communication equipment in the practical application of the transponder transmission unit. |
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