## 1 Introduction  
Software, computing complexes, and artificial intelligence algorithms are being increasingly introduced into power management systems, and include various remote monitoring systems for transmission lines. These systems use collected data to form control signals that make operational decisions [1, 2, 3, 4, 5, 6, 7]. At the same time, functional problems continue to appear during the use of digital technology and computing systems in the online monitoring of the air transmission lines (e.g., sensors of various kinds, analog-digital converters for the processing of recorded signals, and antenna and receiver-transmitting devices of different shapes and sizes [6, 7, 8, 9, 10]) under the influence of thunderclouds and lightning. Most often, these devices are rods, cylindrical, or flat. It is therefore necessary to ensure their electromagnetic compatibility [11, 12, 13]. Moreover, it is not entirely clear how these devices are affected by the different kinds of discharge phenomena that form on various design features of monitoring systems and/or the transmission lines while under the influence of thunderclouds and lightning (e.g., flashes of avalanche and streamer corona, ascending and downward leaders, the main discharge), or how the electromagnetic radiation they create will affect their functionality [12; 14; 15].  
Those impacts are particularly dangerous, as they have frequencies close to the working frequencies of various elements and devices of the artificial intelligence system; this could be from hundreds of hertz to several gigahertz [6; 8; 12]. Sensors, receivers, communication systems, and in some cases, parts of the software-computing control complex of the transmission line monitoring system may be situated directly in the electric field area of thunderclouds and lightning discharge. In this case, exposure to electromagnetic radiation can occur in a wide frequency range, leading to interference, failures, distortions, false positives, and, accordingly, the disruption of normal functionality. Moreover, even the successful triggering of external lightning protection does not eliminate the possibility of an electrical objects' failure; this is a consequence of the impact of electromagnetic radiation of close lightning discharges in various frequency ranges at the different stages of its formation [14].  
It is necessary to achieve a correct interpretation of the spectral characteristics of the electromagnetic radiation that affects the elements of the transmission line monitoring systems in the near field, and to determine their connection with the peculiarities of the formation of the lightning discharge between the thundercloud and the ground [16]. This requires investigation into the connection between the characteristic frequencies of the measured signal and the discharge processes taking place in the thundercloud; this must be conducted on objects on the surface of the earth and under a thundercloud, and between the thundercloud and the ground during the formation of lightning discharge [16; 17; 18; 19; 20].  
The use of artificial thunderstorm cells of negative polarity makes it possible to physically simulate and investigate the characteristics of various types of electrical discharges and the electromagnetic radiation they create. This can be formed on the model elements of the monitoring systems of transmission lines, or be imposed on them during close lightning strikes. The purpose of this work is to physically model (using artificial thunderstorm cells) the spectrum of the possible direct and induced electromagnetic impact of upward streamer discharges in order to determine their influence on the functionality of the intelligent systems that monitor the air transmission lines. These discharges may form on the transmission line intelligent monitoring systems (receiving-transmission devices of different kinds), as well as on the adjacent, grounded structures of the transmission line.