МОДЕЛЮВАННЯ ПОШИРЕННЯ ЕЛЕКТРОМАГНІТНИХ ПОЛІВ ТА ОПТИМІЗАЦІЯ ЕФЕКТИВНОСТІ ЗАХИСНИХ КОНСТРУКЦІЙ

The application of modelling the propagation of extremely low, ultra-high and higher frequency electromagnetic fields for optimising the protective properties and location of electromagnetic screens has been investigated. Modelling of the distribution of the industrial frequency magnetic field in the human body covered with protective clothing has been carried out. It was established that under certain conditions of magnetic flux compression, an increase in the magnetic field level is possible. A model was obtained that allows the design of highly effective protective clothing based on the modelling of the propagation of magnetic fields of electrical machines, and recommendations were given on the location of magnetic screens of the required effectiveness. It has been shown that, given the non-monotonic change in magnetic field intensity with distance from the electric machine, the magnetic screen should be located as far as possible from the points of change in the direction of the magnetic field vector (points of zero field intensity). By modelling the change in the intensity of the man-made and geomagnetic fields by a protective ferromagnetic structure, the limits of the maximum possible shielding of the man-made magnetic field without reducing the intensity of the natural magnetic field below the normative values are determined. It has been shown that modelling the propagation of mobile communication frequency electromagnetic fields is useful not only for developing base station layout schemes, but also for reducing the radiation levels of the communication devices themselves. Even when ensuring reliable communication, base station signals should not be lower than 0.12–0.15 μW/cm2. In this case, the radiation properties of most mobile phones remain at a minimum level. With the transition of mobile communications to the 5G standard, the maximum permissible levels are increasing, due to the increase in the operating frequencies of the equipment and the increase in power attenuation with distance. Under such conditions, some buildings require additional shielding from electromagnetic influences. An easy-to-use calculation is provided, which allows optimising the shielding coefficients of electromagnetic fields of certain frequencies while ensuring the protection of people and stable mobile communication. It is emphasised that the magnetic and electrophysical properties of protective materials are frequency-dependent. Therefore, the calculation results, together with certain simplifications and assumptions made during modelling, may give rise to certain errors. With this in mind, it is advisable to include a margin of safety for the protection of people and the stability of equipment operation in design solutions.