射电天文研究室知识库

射电望远镜具有极高的系统灵敏度,且系统内、系统间及台址内电子设备众多,电磁环境复杂,科学合理地评估台址内电子设备辐射发射对射电天文观测的影响,对系统电磁兼容性设计、无线电管理、屏蔽改造等有重要的指导意义。浅析了射电望远镜系统灵敏度及射电天文领域仪器设备辐射发射相关评估标准;基于射电望远镜系统灵敏度及观测需求,计算了南山25 m射电望远镜馈源口面干扰电平限值,并给出了天线旁瓣增益的计算方法;提出一种基于干扰电平限值、旁瓣增益、干扰测量、路径衰减的电子设备电磁辐射评估方法,并针对南山25 m射电望远镜天线驱动电磁辐射进行了评估,给出了屏蔽需求。

An astronomical radio telescope has extremely high system sensitivities． With increasingly amounts of digital high-speed back-ends and control modules in radio telescopes and intensifying external radio interferences for observational stations，electromagnetic environments of astronomical radio telescopes are increasingly deteriorating． Detailed evaluations of electromagnetic radiation levels of electronic devices affecting radio telescopes can provide important guidance for the electromagnetic compatibility to be considered in design and system improvement of radio telescopes． In this paper we use a simple approach to analyze system sensitivities of telescopes and the relevant assessment criteria of electromagnetic radiation levels of electronic equipments in radio astronomy． We then give a method to calculate side-lobe gains of radio antennas． We further propose a method to evaluate influences of electromagnetic radiations of telescope equipments on observations in radio astronomy． We have calculated the allowed interference limits of the 25m radio telescope at the Nanshan Station of the Xijiang Astronomical Observatory based on system sensitivities and observational requirements of the telescope． Using the calculated interference limits and the method for side-lobe gains in data processing and emission-level evaluation，we have measured the radio spectrum of radiation from the antenna drive system of the 25m telescope． The results lead to the required shielding-effectiveness values of the antenna drive system． The values can be rather helpful for designing the shielding apparatus to mitigate interferences of the antenna drive system．