Vol 25, No 3 (2022)

Articles

Four-wave mixing on thermal nonlinearity with feedback for signal or object waves

Akimov A., Guzairov S., Ivakhnik V.

Abstract

The coincidence of the amplitude reflection coefficients, half-widths of the spatial frequencies bands of a four-wave radiation converter on thermal nonlinearity with feedback for signal or object waves has been shown at equal pump waves intensity. The dependence of the amplitude reflection coefficient, spatial selectivity of the four-wave radiation converter on thermal nonlinearity on the pump waves intensity has been analyzed. An increase in the half-width of the spatial frequency band is observed with an increase in the pump waves intensity at the compensation for the phase shift arising as a result of the propagation of the pump waves in the medium. There is a threshold value of the pump waves intensity, above which the value of the amplitude reflection coefficient of the four-wave converter with feedback for signal or object waves, is less than in the absence of feedback.

Physics of Wave Processes and Radio Systems. 2022;25(3):9-15
pages 9-15 views

Investigation of electrical properties of photosensitive structures of reduced dimension based on silicon

Poluektova N., Shishkina D., Bazanov A., Perebalin R., Shishkin I., Latukhina N.

Abstract

In this paper, we propose a method for reducing the energy loss of photosensitive structures based on nanocrystalline silicon using passivating coatings of dysprosium fluoride. Since this material has good optical and photoelectric properties, when preparing Si/DyF3 structures, the dielectric film makes it possible to reduce the number of recombination centers and increase light absorption. Methods for creating and studying photosensitive structures with coatings are shown. A technique for determining the thickness of a dysprosium fluoride coating due to light interference is described. The results of studying the photosensitivity spectra and the reflectance of the obtained photosensitive structures are presented. The positive effect of silicon nanostructures, as well as dysprosium fluoride films on the photosensitivity spectra of the structures, is shown. With the help of the data obtained, it is planned to improve the existing technology for creating photosensitive structures based on porous silicon in order to increase their output characteristics.

Physics of Wave Processes and Radio Systems. 2022;25(3):16-23
pages 16-23 views

Spectral decomposition for a QS based delay model with Erlang and hyperexponential distributions

Tarasov V.

Abstract

This article is devoted to the study and obtaining a closed-form solution for the average delay of claims in a queue for a QS formed by two flows with Erlang and hyperexponential distributions of the second order for time intervals. As is known, the Erlang distribution ensures the coefficient of variation of the arrival intervals is less than one, and the hyperexponential distribution is greater than one. It is also known that the main characteristic of the QS, the average delay, is related to these coefficients of variations by a quadratic dependence. Studies of G/G/1 systems in queuing theory are topical due to the fact that they are used in modeling data transmission systems for teletraffic analysis. To solve the problem, the method of spectral decomposition of the solution of the Lindley integral equation was used. The spectral decomposition for the system under consideration made it possible to obtain a closed-form solution for the average delay of requests in the queue. For the practical application of the results obtained, the method of moments is used.

Physics of Wave Processes and Radio Systems. 2022;25(3):24-28
pages 24-28 views

Evaluation of the possibilities of 3D-printing for the making of waveguide photonic crystals

Mikhailov A., Ryabov E., Sergeev S.

Abstract

The paper considers the possibilities of 3D printing technology for the manufacture of X-band waveguide photonic crystals. The photonic crystals for an EIA WR-90 standard rectangular waveguide with a cross section of 22,86 × 10,16 mm2 in the X-band were designed and manufactured. Numerical modeling of the reflection characteristics of photonic crystals of several designs in the OpenEMS software package was carried out. Based on the simulation results, the best types of the structures were selected, which were manufactured using the physical modeling technique by the fusion method of PETG plastic. Experimental study of the manufactured layouts and comparison of the experimental data with the numerical simulation data were performed. The best types of manufactured models of waveguide photonic crystals showed transmittance and reflection drop in the corresponding frequency bands of the order of 15–20 dB, which is acceptable for technical applications. The numerical modeling results are in good agreement with experiments, thus indicating the high efficiency and good control of the topology and dimensions of the manufactured photonic crystals’ structural elements in the used type of 3D printing technology.

Physics of Wave Processes and Radio Systems. 2022;25(3):29-35
pages 29-35 views

Equivalent circuit of a dielectric in a wide frequency range (0 Hz – 500 MHz)

Dmitrikov V., Shushpanov D.

Abstract

Based on the measured impedance of the dielectrics an equivalent high frequency (0 Hz - 500 MHz) circuit model was built. The equivalent circuit model was built taking into account the physical processes occurring in the dielectric. The attempt explaining why the frequency characteristics (modulus and phase) of the dielectric complex impedance have such a character in a wide frequency band (up to 500 MHz) was made. It was shown that for constructing an equivalent circuit model (structure and parameters), measuring only the dielectric’s resistance modulus is not enough. It is also necessary to measure the phase of the dielectric complex resistance, which is ignored in many works on the synthesis of an e dielectric equivalent circuit.

Physics of Wave Processes and Radio Systems. 2022;25(3):43-57
pages 43-57 views

Client-server system for monitoring the quality of TV broadcasting in Russia

Karyakin V.

Abstract

The strategy for the development of television and radio broadcasting in the Russian Federation until 2025 specifically states the need to ensure the reliability of uninterrupted television and radio broadcasting. The quality of DVB-T2 broadcasting is estimated by the data transmission rate and the bit error rate BER (Bit Error Ratio) stability margin «at the last mile» in the retransmitters’ broadcast zones. The distributed client-server system of broadcast quality monitoring in RF, proposed in the article, uses the necessary equipment, including BER sensors based on programmable receivers combined with single-board microcomputers implemented on SoC processors. Collection and processing of data in broadcasting areas with the help of the proposed monitoring system will allow specialists engaged in practical network development to make an objective conclusion about the necessity and ways of SFN network reconstruction to provide uninterrupted TV and radio broadcasting in RF. Modernization and technical re-equipment of SFN networks will provide a solution to the problems related to certification of satellite earth stations and transmitters of SFN networks, provision of various services and broadcasting services of DVB-T2 standard to the population with high quality.

Physics of Wave Processes and Radio Systems. 2022;25(3):36-42
pages 36-42 views

Irregularities in a metal-dielectric shielded waveguide with low losses for the frequency range 90–100 GHz

Krutskikh V., Ushkov A., Ariqat H., Zavitaev D., Mirzoyan A.

Abstract

This article is devoted to the study of waveguide metal-dielectric structures in the frequency range of 90–100 GHz with low losses up to 0,05 dB/m. The paper considers the effect of sharp irregularities on a section of a regular line, which leads to a change in the parameters of a metal-dielectric closed waveguide path. In practice, irregularities have a negative impact on the transfer characteristic of the waveguide. Therefore, the types of irregularities often found in modern devices were investigated. As a result of the analysis of the losses caused by the rupture of the dielectric rod and the rotation of the polarization plane, the approximated characteristics of the transfer function of the waveguide line with irregularity were obtained.

Physics of Wave Processes and Radio Systems. 2022;25(3):58-66
pages 58-66 views

Antenna array control system with combination of strength and flexible scanning programs

Vinnik L., Mishchenko S.

Abstract

The structure of the antenna array control system with a combination of strengh and flexible scanning programs is proposed, characterized by the introduction of additional modules of statistics and expert assessments in the feedback circuit between the secondary processing module and hardware and software complexes for the formation of transmitting and receiving antenna array radiation patterns. The implementation of this structure allows for the formation of an additional transmitting and several receiving beams to confirm marks that do not meet the specified detection criterion. An algorithm for controlling an active phased array antenna has been developed, characterized by a procedure for additional confirmation of marks with a low signal-to-noise ratio due to the formation of additional transmitting and receiving beams. The estimates of the gain from the implementation of the proposed structural scheme of the antenna array control system and the algorithm of its functioning are obtained.

Physics of Wave Processes and Radio Systems. 2022;25(3):67-72
pages 67-72 views

The calculation of a two-cascade long-period fiber grating of the refractive index

Budaragin R., Kurzenkov M., Radionov A., Salasenko Z.

Abstract

A method is proposed for calculating the spectral characteristics of cascade long-period fiber gratings of the refractive index of the core based on the method of partial regions and decomposition. According to the method, the structure is represented as a cascade connection of basic inhomogeneities, each of which is a junction of several optical fibers with different dielectric and geometric parameters. Approbation of the method was carried out by reducing the structure to a single long-period fiber grating and comparing the results with the results obtained using other calculation methods. The results matched graphical accuracy. The advantage of the method is the possibility to theoretically study the effect of dielectric and geometric parameters on the spectral properties of the structure, as well as significantly save time resources. The transmission spectra of gratings with different parameters of period T, grating length L, and distance between gratings Lf are presented.

Physics of Wave Processes and Radio Systems. 2022;25(3):73-81
pages 73-81 views

Application of colorimetry in neural network methods of fire detection in woodlands

Kuzmenko A.

Abstract

Currently, neural network methods of fire detection have been used to monitor fires in forests. To date, such systems have been developed as the Prometheus project, the Fire Video Detector, and the Artificial Intelligence University method. These methods make it possible to determine a fire with an accuracy of more than 90 %, for which a combination of recurrent and light-line neural networks is used. The article proposes a method for improving the efficiency of neural network methods for determining fires in forests based on computer colorimetry. The use of this method makes it possible to increase the efficiency of neural network methods for detecting fire when using multiple cameras of a video surveillance system. Thus, the article presents a comparison of the performance of a convolutional neural network with and without the use of a colorimetric module. According to the results, the efficiency of work has increased by more than 20 %.

Physics of Wave Processes and Radio Systems. 2022;25(3):82-85
pages 82-85 views

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