Search results

The paper presents a calculation of the magnetic field over the cable with damage. The cable with damage is replaced to equivalent circuit «conductor - shield». The conductor and the shield is considered as two single-wire lines, loaded on the characteristic impedance to avoid reflections. For this equivalent circuit defined sine wave signal change in the conductor and the cable shield. These results indicate that in cable fault location conductor current is significantly changed and shield current reaches the maximum value. The values of the shielding factor is determined at dif-ferent frequencies for the continuous tubular aluminum conductor and steel spiral conductor. The magnetic field is determined on the earth surface over the cable with metal shield having a «con-ductor - shield» damage taking into account the shielding factor. The results show that the module and phase of magnetic field is incremented in the cable fault location, which can be fixed on the earth surface. The results of calculation will improve the methods and hardware for cable fault lo-cation searching.

In this article a shielding effectiveness calculation method for the radio electronic equipment is considered. Monolayer and multilayer shields made with aluminum, cuprum, steel is investigated. Interaction of pulse magnetic field and conductive shield is simulated using finite difference time domain method. Frequency and time dependencies for the shield impedances are shown. Also pictures of electromagnetic field distribution near shielding are presented. Time dependencies of electric field on the shield external and internal borders are shown.

Station radio communication is an integral part of the technical means involved in the organization of a safe transportation process. Increasing the signal power in places with a complex electromagnetic environment remains an urgent issue. A passive repeater can serve as a solution to this issue, therefore the purpose of this work is to test the possibility of increasing the signal power level using a passive repeater.The article provides an analysis of a passive repeater used as a device that improves the quality of radio communications in places with a difficult electromagnetic environment. The differences between the use of a passive repeater and active relay stations are given.An analysis of the existing methods for calculating the parameters of passive repeaters was carried out, on their basis, modeling and calculation of the parameters of a passive repeater were carried out for the development and conduct of research in real conditions at a railway station. The design, materials of manufacture of the passive repeater, as well as the measurement scheme in real conditions are presented.The study is based on theoretical calculations and performance checks in real conditions and comparison of the results obtained. As a result of the study, it was found that the use of a passive repeater in a complex electromagnetic environment makes it possible to increase the signal power level, thereby increasing the stability of radio communication.It was noted that it is necessary to refine the existing method for calculating a passive repeater, since the above technique was used when calculating passive repeaters over long distances. A variant of fastening passive repeaters without the development and installation of additional new structures is proposed, the need to organize further protection against overvoltage is indicated.The results obtained will be useful in the development of new radio relay communication lines and the modernization of existing ones for places with a difficult electromagnetic environment and rough terrain.