Monitoring And Analysis Of Electromagnetic Interference Of A 500-meter Spherical Radio Telescope (FAST)

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is a Chinese mega-science project;the main structure of the telescope had been completed in September 2016.Till now,the debugging of the system is ongoing.Due to the high sensitivity of radio telescope,the radio observation is susceptible to electromagnetic interference.In order to protect the radio environment around FAST and ensure the scientific output,a region called as a radio quiet zone(RQZ)has been established by using spectrum management policies and making electromagnetic compatibility(EMC)design of telescope.The work in this article focuses on this topic.There are four works in this article: a study of evaluation on radio interference of FAST visitor's electronic devices,radio environment monitoring,testing the shielding facility of FAST,building FAST RQZ database web site.The electromagnetic radiation measurements of the typical electronic devices have been made at the microwave chamber.Moreover,the theoretical calculation and on-site measurements between the critical position and FAST feed have also been implemented.Combining the measurement results,the evaluation of the level of RFI generated by devices shows that the observation of the telescope will be inferred by these kinds of devices more or less.We also use this analysis method to select the necessary devices in the main building of the FAST.Radio environment monitoring is a routine job.According to the measurement results,the identification the source of interference in the observed spectrum and negotiate has been carried out and helps the coordination with the other radio services.One main method to be used in the FAST EMC design is shielding.The requirements for shielding effectiveness of telescope instruments have been calculated and presented.A new Shielding efficiency measurement method has also been developed and tested.This work is meaningful for protecting the radio environment of FAST.The preliminary database web site has been established and data management function has been designed,which is convenient for RFI monitoring data management and relevant information sharing to the user of FAST.FAST RQZ database web site is an important auxiliary tool for radio environment protecting.This article aims to protect FAST from electromagnetic radiation interference.The job in the paper has been involved into the construction of FAST and will be one indispensable job for the future operation and maintenance.