Radio Frequency Interference to a Radio Telescope from a High-Voltage Power Line

On one hand, this paper analyzes the limits of electromagnetic interference(EMI) from a high-voltage power line torelatable by a radio telescope according to the protection criteria used for astronomical radio measurements recommended by the International Telecommunication Union (ITU) and the characteristics of EMI. On the other hand, this paper presents a study of the distance-dependent attenuation of the corona-discharge radiation based on the physical mechanism of corona discharge, established electric-oscillator model, and the image-charge method for an electric oscillator. This paper also considers particular cases of the Five hundred meters Aperture Spherical Telescope (FAST), and analyzes the minimum distance to be left between a high-voltage power line and the FAST as well as problems to be noticed.More specifically the paper analyzes the effects of the Radio Frequency Interference (RFI) from high-voltage power lines. There are two main causes of such RFI: the discharge caused by the imperfection of insulation and the corona discharge. The first effect can be mitigated by utilizing better insulation material and through regular maintenance. The paper concentrates on the corona discharge. An oscillating electric-charge model is adopted to calculate the strength of the interference generated by the corona discharge, and the influence of the terrain between the power line and the telescope is also taken into account. Taking the ITU criterion ITU-R RA. 769-2 for radio astronomy, and considering various FAST observing modes, we give preliminary suggestions on allowable distances from power lines of different voltages. The results should be considered qualitative only, as the allowable distances need to be further refined according to the terrain around the region and the shape of the telescope antenna.