Vol 26, No 3 (2023)

Background. Presence of possibility of analytical definition of a part of parameters of various radio devices, optimum by criterion of maintenance of preset values of modules and phases of transfer functions on necessary quantity of frequencies, considerably reduces time of numerical optimization of other part of parameters by criterion of formation demanded PFC and FFC in a strip of frequencies. Till now such problems dared concerning radio devices only with one cascade of type «a nonlinear part - the coordination the device» or «the coordination the device - a nonlinear part». In quality согласующего devices were used the jet, resistive, complex or mixed two-port networks. The problem of multicascade radio devices with jet two-port networks is solved also. Change of basis for the coordination two-port networks and a place of inclusion of a nonlinear part leads to change of area of a physical realizability.

Aim. Working out of algorithms of parametrical synthesis of radio devices with any quantity of identical and unequal cascades of type «the coordination the complex two-port network - a nonlinear part» by criterion of maintenance of the set frequency characteristics. Nonlinear parts are presented in the form of a nonlinear element and parallel either consecutive on a current or pressure of a feedback.

Methods. The theory of two-port networks, matrix algebra, a decomposition method, a method of synthesis of actuation devices microwave, numerical methods of optimisation.

Results. In interests of achievement of the specified purpose systems of the algebraic equations are generated and solved. Models of optimum two-port networks in the form of mathematical expressions for definition of interrelations between elements of their classical matrix of transfer and for search of dependences of resistance of two-poles from frequency are received. It is shown, that at certain parities between quantity of identical cascades and values of resistance of a source of a signal and loading of the one-cascade radio device frequency characteristics of one-cascade and multicascade radio devices appear identical or similar. Such schemes are named by equivalent. Use of unequal cascades leads to substantial growth of a working strip of frequencies.

Conclusion. The comparative analysis of theoretical results (PFC and FFC radio devices, value of parameters), received by mathematical modelling in system MathCad, and the experimental results received by схемотехнического of modelling in systems OrCad and MicroCap, shows their satisfactory coincidence.

Background. Presence of possibility of analytical definition of a part of parametres of various radio devices, optimum by criterion of maintenance of preset values of modules and phases of transfer functions on necessary quantity of frequencies, considerably reduces time of numerical optimisation of other part of parametres by criterion of formation demanded PFC and FFC in a strip of frequencies. Till now such problems dared concerning radio devices only with one cascade of type «a nonlinear part - the coordination the device» or «the coordination the device - a nonlinear part». In quality devices were used the jet, resistive, complex or mixed two-port networks. The problem of multicascade radio devices with jet two-port networks is solved also. Change of basis for the coordination two-port networks and a place of inclusion of a nonlinear part leads to change of area of a physical realizability.

Aim. Working out of algorithms of parametrical synthesis of radio devices with any quantity of identical and unequal cascades of type «a nonlinear part the coordination the complex two-port network» by criterion of maintenance of the set frequency characteristics. Nonlinear parts are presented in the form of a nonlinear element and parallel either consecutive on a current or pressure of a feedback.

Methods. The theory of two-port networks, matrix algebra, a decomposition method, a method of synthesis of actuation devices microwave, numerical methods of optimization.

Results. In interests of achievement of the specified purpose systems of the algebraic equations are generated and solved. Models of optimum two-port networks in the form of mathematical expressions for definition of interrelations between elements of their classical matrix of transfer and for search of dependences of resistance of two-poles from frequency are received. It is shown, that at certain parities between quantity of cascades and values of resistance of a source of a signal and loading of the one-cascade radio device frequency characteristics of one-cascade and multicascade radio devices appear identical or similar. Such schemes are named by equivalent.

Conclusion. The comparative analysis of theoretical results (PFC and FFC radio devices, value of parametres), received by mathematical modelling in system MathCad, and the experimental results received by modelling in systems OrCad and MicroCap, shows their satisfactory coincidence.

Background. To ensure the integrity, stability of operation and security of the unified telecommunication network of the Russian Federation, as well as to solve the issues of electromagnetic compatibility of radio-relay communication facilities, it is required to use antennas that satisfy both mandatory requirements fixed at the legislative level and requirements of a recommendatory nature of international and regional levels.

Aim. To establish compliance of the most frequently used zigzag antennas in radio-relay communication facilities with the requirements of the current legislation and international standards on the basis of numerical and experimental evaluation of their characteristics.

Methods. On the basis of numerical methods the characteristics of the considered antennas were calculated, and also measurements of these characteristics were carried out in an anechoic shielded chamber.

Results. The results of numerical and experimental estimation of gain, voltage standing wave ratio, antenna patterns, crosspolarization decoupling and complex impedance of the double zigzag antenna with UHF reflector of the radio-relay communication range are presented. It is shown that this antenna provides operation in a wide frequency band, and in the considered section of the range does not fully meet the requirements for antennas of radio-relay communications.

Conclusion. On the basis of the analysis of the requirements of the current legislation and international requirements for the antennas of radio-relay communication facilities and the results of numerical and experimental evaluation of the characteristics of the antennas under consideration, it was established that they comply with the requirements of ITU Recommendations ITU-R F.699 in terms of the envelope level of antenna patterns, side and back radiation, except for the beginning of the range section, where there is some excess of the envelope level. The requirements of GOST R 50867-96 for the level of crosspolarization maxima (or the level of crosspolarization radiation in a given spatial sector of angles near the main radiation direction) are not met.

Background. The modern development of the mining industry is characterized by the search for new mining technologies, increasing the complexity, depth, scale of workings and the danger of work, which leads to the search for approaches in building information and communication systems with increased functionality, namely, with the possibility of combining into a single system of mining automation tools, sensors, tunneling equipment, communication equipment, navigation, controls, equipment operating in an emergency situation. Since most underground facilities can be considered quasi-one-dimensional (mines, subways, sewers), transmission lines laid along tunnels can be effectively used to organize data transmission in them.

Aim. Consider the physical side of the operation of the information and communication system in the medium and high frequency ranges.

Methods. The dependence of the field strength in a tunnel with single-wire and bifilar lines laid in the tunnel was obtained using electrodynamic modeling by the finite element method.

Results. The values of attenuation in workings with different medium parameters and attenuation dependences obtained experimentally in a coal mine are given. On average, the signal attenuation is 15 dB per 1 km.

Conclusion. A digital medium-wave system based on bifilar lines has significant advantages when deployed over VHF communication systems. It can be used as a base, and if necessary, supplemented with VHF technologies (Bluetooth, Wi–Fi), for example, for personnel using an explosion-proof smartphone, and in areas where increased throughput is required, in places of active mining operations in mines and concentration of technological equipment and personnel.

Background. The need to describe the features of the formation of minimum frequency shift keying signals, reveal the advantages of this type of modulation, provide circuits for digital demodulators of minimum frequency shift keying signals that provide the best reception noise immunity, and indicate ways to improve the spectral efficiency of minimum frequency shift keying signal modems. Aim. Various options for constructing digital modems for minimum frequency shift keying signals, features of modem circuits for even and odd numbers of half-periods on segments of the duration of transmitted messages, as well as the specifics of the formation of reference oscillations in coherent demodulators are considered. Methods. The principle of operation of modulators and demodulators of minimum frequency shift keying signals is explained by the timing diagrams of signals at various points in the paths for the formation and detection of minimum frequency shift keying signals. This representation ensures the reliability and clarity of the operation of modems of minimum frequency shift keying signals. Results. It is shown that coherent demodulators of minimum frequency shift keying signals provide the same noise immunity as opposite signals of relative phase shift keying, but at the same time they have a constant signal level and a smaller spectrum width. A dual-channel minimum frequency shift keying signal modem doubles the spectral efficiency of a single-channel modem, but the signal level becomes inconsistent. Conclusion. Information is given explaining the reason for the widespread use of minimum frequency shift keying signals in cellular communication systems, in space communication systems and in cordless phones, as well as ways to further improve digital modems of minimum frequency shift keying signals.

Background. Interest in the biological effects of electromagnetic radiation on biological objects is associated with the possibility of their use in solving a number of fundamental and applied problems: from the consideration of biological feedbacks in real time, which allows the development of electronic medical complexes, to the creation of neuro-computer interfaces, including components of living cells.

Aim. The paper shows the development of a device for influencing biological objects with a permanent magnetic field, which allows modeling the basic parameters of the physical factor, for conducting a magnetobiological experiment with normalization of the effects of non-ionizing radiation of the specified parameters.

Methods. The device for influencing biological objects of constant magnetic field allows to obtain, in a large volume, the most homogeneous magnetic field.

Results. Mathematical modeling of changes in the morphofunctional state of the adrenal cortex according to eleven biological parameters at different periods of exposure to normalized constant magnetic field when exposed to the maximum permissible level was evaluated by the deviation of the interval indicator and its normalized value. The effect of this factor led to a deviation of the integral index in the glomerular zone of the adrenal glands on the 30th day was – 6,53 ± 1,30*10^-2, later on the 60th day the deviation increased by 8,28 ± 1,55*10^-2, on the 90th 4,84 ± 1,50*10^-2, then on the 120th day, it did not differ from normalized. Conclusion. After the termination of the constant magnetic field in a series of 15–30 mT experiments, the morphofunctional state of the thymus returned to normal. Thus, the device is recommended for use in experimental activities.