Analysis And Evaluation Of EMC Performance In The Interior Of Radio Telescope System

There are many electronic devices in the radio telescope system and the station site,and the problem of EMC is prominent.On the one hand,the electromagnetic emission in the site will radiate around the radio telescope site,reduce the signal-to-noise ratio of the observation system and increase the difficulty of data processing;on the other hand,it will enter the receiver system through the side lobe of the antenna,causing serious interference to the observation task of the radio telescope.Therefore,it is of great significance to analyze the characteristics of electromagnetic emission in the radio telescope system site and propose a set of feasible system level EMC evaluation methods.This paper takes the radio telescope system as the research object,analyzes the electromagnetic emission characteristics of the main sub-systems in the station site,and estimates the interference amount to the radio telescope system;gives the idea of EMI suppression of the hierarchical weak link in the station site,and studies the influencing factors.Based on the theory of evaluation,a set of EMC evaluation method and system suitable for radio telescope system site is constructed.The research idea of this paper is "EMC equirement analysis ? electromagnetic coupling element analysis within the station site ? electromagnetic emission characteristics and interference prediction of subsystem ? layered EMC suppression ? system level EMC design evaluation",which is also applicable to solve complex EMC problems in other fields.The specific research contents are summarized as follows:First of all,based on the electromagnetic topology theory,the electromagnetic topological structure and electromagnetic coupling sequence diagram of the radio telescope system site are established,which provides the theoretical basis for the construction of the interference prediction model;Then,combined with the radiation emission power level,radiation emission path loss and antenna sidelobe gain of the system equipment,the calculation model of the interference amount is constructed;the electromagnetic emission characteristics of the main subsystems in the radio telescope system site are analyzed,and the interference amount from each system to the feed source interface of the radio telescope system is estimated.Next,Based on the common classification of interference sources in the station site,the EMI suppression idea of "three-layer shielding and filtering" is adopted;the suppression methods of buildings,case or cabinet,equipment shell and electrical introduction are studied respectively,and the factors affecting the shielding effectiveness are analyzed by using simulation and actual test;the EMC design scheme in the station site is given,and the computer system is taken as an example Tested and verified.Finally,through the comparison of the advantages and disadvantages of different methods,the weighting method and evaluation method of radio telescope system are established,and the layered evaluation index system is established,which takes the EMC performance of radio telescope system as the target layer,the main subsystem as the criterion,and contains multiple indexes,which comprehensively reflects the EMC performance of radio telescope system in the site and meets the needs of shielding design evaluation;For different indicators,the difference transformation method,interval transformation method and Delphi method are used to complete the data normalization and quantitative processing;TOPSIS is used to evaluate,and the entropy weight method is introduced to modify the index weight obtained by AHP,and the evaluation results are given for different design cases.