Doklady BGUIR最新文献

{"title":"Analysis of Methods for Measuring Parameters of the Radiation Pattern of Antenna Systems","authors":"A. Sharamet, A. Lysy","doi":"10.35596/1729-7648-2023-21-6-75-83","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-75-83","url":null,"abstract":"Measuring the parameters of the antenna pattern is an urgent task in the development and operation of radio engineering systems. This problem can be solved by various methods of antenna measurements. In this case, depending on the radiation zone of the antenna, two main groups of measurement methods are distinguished: methods of direct measurements in the far-field and methods of reconstructive measurements in the near-field. Methods of antenna measurements in the far-field, which allow obtaining direct results, are the most developed and simple, since in the case of the far-field, the angular distribution of the field, regardless of distance, is characterized by a radiation pattern. Methods of the near-field are based on measuring the amplitude-phase distribution of the orthogonal components of the electromagnetic field in the near zone with subsequent recalculation of the parameters and restoration of the spatial radiation pattern of the antenna under study. The comparative analysis of the main groups of antenna measurement methods shows that at the present stage of their development, due to a number of advantages, measurement methods in the near-field with subsequent reconstruction of the radiation pattern of the studied antenna in the far-field are most widely used.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"48 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139536203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composite Materials of Epoxy Resin–W System for Radiation Shielding Against Gamma Radiation","authors":"A. A. Rotkovich, D. I. Tishkevich, S. A. German, A. A. Bondaruk, S. V. Leonchik, E. S. Dashkevich, V. M. Fedosyuk, A. V. Trukhanov","doi":"10.35596/1729-7648-2023-21-6-5-13","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-5-13","url":null,"abstract":"Сomposite materials based on the epoxy resin–W system with varying W content (0–80 %) were obtained using the method of chemical curing. Microstructural investigations of the samples showed that with increasing W content there is a more uniform distribution of grains in the epoxy resin matrix could be observed. Agglomeration of W grains is noted for samples with filler content up to 40 %. Statistical analysis of the grain size of the initial W powder revealed that the probable diameter of W grains is 475 nm. The values of effective and relative densities of the experimental samples were obtained using the Archimedes method. The effective density varied from 1.16 to 4.36 g/cm3 with W powder content rising. The relative density values received ranged from 91 to 94 %, indica ting that there were no significant defects in the samples. X-ray diffraction analysis showed the presence of vcc-W and WO2 phases, indicating the oxidation of W in the thin surface layer of the powder. Calculation in Phy-X/PSD software allowed to evaluate the gamma radiation shielding efficiency for the epoxy resin–W system composite materials in 0.8–2.5 MeV energy range. It was observed that samples with filler content of 60 and 80 % were the most suitable for radiation shielding. It was found that the addition of W powder to the epoxy matrix contributed to the reduction of half attenuation layer values by 3.5 times from 9.448 to 2.672 cm for samples with 0 and 80 % W content, respectively, for 1.25 MeV radiation energy. The obtained results demonstrate the high efficiency of the proposed composite materials for shielding gamma radiation, which makes them a perspective candidate for manufacturing radiation shields.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139630228","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of BJT-JFET Operational Amplifiers on the Master Slice Array","authors":"A. Kunts, O. Dvornikov, V. Tchekhovski","doi":"10.35596/1729-7648-2023-21-6-29-36","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-29-36","url":null,"abstract":"The use of dual-gate field-effect transistors located on the base matrix crystal MH2XA031, controlled by a p–n junction needed to reduce the input current of operational amplifiers is studied. Typical circuits of operational amplifiers, containing: source repeaters connected to the inputs of the operational amplifier on complementary bipolar transistors; input differential stage on p-JFET with a “current mirror” load on n–p–n-transistors; input differential in the form of a “folded cascode” on a p-JFET are analyzed. To minimize the input current, it is re commended to use bootstrapped feedback to keep the drain-to-source voltage of the input JFETs low, independent of the input common-mode voltage, and to connect only the top gate of the dual-gate JFET to the op-amp input. The electrical circuits for MH2XA031 elements and the results of circuit simulation of the developed amplifiers, called OAmp10J, OAmp11.1, OAmp11.2, are presented. Accounting the established features of the input stages and operating modes of active elements in circuit design will allow to create an operational amplifier with the required combination of basic parameters.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139536462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protection Against Simulating Interference Based on Coherent Storage and Pulsed Probing Signal with a Random Initial Phase","authors":"S. Heister, Qianlan Huang","doi":"10.35596/1729-7648-2023-21-6-53-60","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-53-60","url":null,"abstract":"The confrontation between radar stations and radio electronic countermeasure systems leads to constant advancements on both sides as electronics continue to develop. This multifaceted confrontation determines the success of each side primarily based on the comprehensiveness of analysis and the correctness of the adopted system decisions. Occasionally, decisions are made in pursuit of quality, resulting in success in one aspect but failure in another. One such example is the transition to building radar stations based on true coherence principles. This work highlights the issue of protecting radar stations with true coherence from simulative interference. A method is presented for protecting against “near” simulative interference, which is the most dangerous and is generated between the radar stations and an aerial vehicle equipped with a radio electronic countermeasure systems. The method is based on combining an impulse probing signal with a random initial phase and coherent inter-period accumulation of the received signal.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"52 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139536100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Digital Beamforming Features in Subaperture Antenna Arrays of Highly Informative Space Radars with Aperture Synthesis","authors":"S. V. Kozlov, V. V. Radionovich","doi":"10.35596/1729-7648-2023-21-6-70-74","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-70-74","url":null,"abstract":"It is shown that during digital beamforming in a subaperture antenna array of highly informative space radars with synthetic aperture, it is necessary to provide a procedure for equalizing the time delays of the subaperture output signals for transmission and reception. It has been established that losses in the signal-to-noise ratio on a radar image of a point target for a typical aperture size at an elevation angle of 0.7 m and a signal spectrum width of 600 MHz reach 2.1 and 7.5 dB for off-nadir angles of 21° and 50°, respectively. Recommendations are formulated for equalizing time delays for transmission and reception based on spectral processing. Simulation results are presented.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"111 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139630476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fiber-Optic Sensor for Identifying Liquids and Determining Solutions Concentration","authors":"A. Zenevich, T. G. Kovalenko, E. Novikov, S. V. Zhdanovich","doi":"10.35596/1729-7648-2023-21-6-14-20","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-14-20","url":null,"abstract":"Fiber-optic sensors for identifying liquids and determining the concentration of solutions have been studied with the possibility of using various types of single-mode optical fibers produced by industry and widely used in optical cables and telecommunications to create sensors for identifying liquids and determining the concentration of solutions. To identify liquids with different refractive indices and determine the concentration of substances dissolved in water, the peak value of the reflectograms of the optical fiber located at the interface between the optical fiber core and the environment can be used as an information parameter. The value of the information parameter depends on the refractive index of the liquid in which one end of the optical fiber is located. The parameters of fiber-optic sensors for identifying liquids and determining the concentration of solutions were studied by optical reflectometry in different wavelength ranges of optical radiation with a duration of reflectometer probe pulses from 25 to 300 ns. It has been established that the fiber-optic sensor can operate at any wavelength of optical radiation corresponding to the transparency windows of the optical loss spectrum of the optical fiber. The influence of the length of the optical fiber between the recording device and the place where the concentration of a liquid solution is determined using a fiber-optic sensor was studied. The possibility of creating a fiber-optic sensor for determining the concentration of the liquid solutions based on optical fibers has been demonstrated.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"52 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139536096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of Tubular Aluminum Oxides by Local Electrochemical Anodization in Organic Electrolytes and Their Anti-Reflection Properties","authors":"S. K. Lazarouk, V. V. Dudich, T. I. Orekhovskaya, D. A. Sasinovych, L. P. Tomashevich, A. A. Ustimenko, A. A. Povzhik, N. A. Kalanda, D. A. Symonenko, S. M. Ivanyuta","doi":"10.35596/1729-7648-2023-21-6-21-28","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-21-28","url":null,"abstract":"Research has been carried out on the formation of tubular aluminum oxides by local electrochemical anodization in aqueous solutions of organic acids such as formic, citric, tartaric, malic and others. Self-ordered nanostructures formed this way can be used in the manufacture of various optical devices. Tubular aluminum oxides formed by local electrochemical anodization in organic acids have a high concentration of anionic complexes containing carbon atoms over 10 at.%. Studies of reflection spectra showed effective anti-reflection properties of films with a specular reflection coefficient of 0.7–1.4 %.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"18 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140513965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Helitron: Operation at High Frequency Orbital Harmonics and the Mode of Electron Phase Selection","authors":"A. A. Kurayev, V. Matveyenka","doi":"10.35596/1729-7648-2023-21-6-37-44","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-37-44","url":null,"abstract":"The possibilities of improving the output characteristics of the helitron in two directions have been studied – increasing the efficiency in the phase selection mode of electrons and increasing the operating frequency through the use of a multi-lamella electrodynamic system (increasing the azimuthal index n of the operating mode). The results obtained during the experiments indicate the unique capabilities of the helitron at very high harmonics of the electron orbital frequency: up to n = 96, the device has an acceptable efficiency for low-power generators in the electron phase selection mode. This opens up prospects for using such a generator in the millimeter wavelength range. However, in this range, instead of a high-frequency multi-lamella line, an azimuthally corrugated rod with a depth of longitudinal grooves ∆r = λ/4 should be used. This is most effective in providing thermal conditions.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"40 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139536031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of Signals with Chaotic Varying Forms and Low Intercept Probability","authors":"V. Р. Tuzlukov","doi":"10.35596/1729-7648-2023-21-6-61-69","DOIUrl":"https://doi.org/10.35596/1729-7648-2023-21-6-61-69","url":null,"abstract":"Low probability of intercept performance of direct-sequence spread-spectrum system with chaotic spreading sequences is investigated. The energy detectors, synchronous and asynchronous, coherent and non-coherent structures are studied here to detect the presence of chaotic direct-sequence spread-spectrum signals. Simple detection approach using a binary correlation function to detect nonbinary chaotic sequences is proposed. The expressions of detection probabilities of chaotic spreading signals are derived. Comparisons between systems using chaotic and binary sequences are given in terms of the low probability of intercept performance, and the performance improvement with chaotic spreading sequences is observed.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"113 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139630455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron-microscope investigations of the Pt-Si system during its rapid thermal treatment","authors":"V. Saladukha, V. Pilipenko, F. Komarov, V. Gorushko","doi":"10.35596/1729-7648-2020-18-3-88-96","DOIUrl":"https://doi.org/10.35596/1729-7648-2020-18-3-88-96","url":null,"abstract":"The paper is dedicated to investigation of the influence of rapid thermal treatment on the microstructure of platinum silicide. The Pt films 43.7 nm thick were applied on the substrates of the monocrystal silicon by means of the magnetronic sputtering of platinum with the purity of 99.95 % on the МРС 603 set-up with the cryogenic pumping to the pressure not worse than 5×10 Pa. As an operating medium, argon was used with the purity of 99.933 %. Rapid thermal treatment of samples was performed in the thermal balance conditions by irradiating the non-working side of the wafer with the incoherent light flow in the nitrogen atmosphere during 7 s at the temperatures of 200–550 oС. The irradiation source in the set-up was represented by the quartz halogen incandescent lamps. The comparative analysis was done through the traditional long thermal treatment of the platinum films at a temperature of 550 С for 30 min in the nitrogen atmosphere. Investigations of the platinum silicide microstructure were performed by means of the transmission electron microscopy which demonstrated that the increase in the RTT temperature initiates first the annealing of defects on the inter-grain boundaries, which is evident from the more distinct contrast from the grains, and then one can observe their growth reflecting the forming of the new phase (silicide one). Such progress of changes of the platinum silicide microstructure and of the size of the grains with the increase in treatment temperature is determined by the heat of its forming. As the Pt2Si phase forming heat is minimum and constitutes 10.4–16.8 Kkal/atom of metal, and for PtSi – 15.7–25.5 Kkal/atom of metal, then the forming of a stable PtSi structure requires a higher temperature. The authors carried out calculations of the activation energy of the diffusion synthesis of platinum silicide during rapid thermal treatment. The calculations show that it is 0.37 eV smaller, than during the long thermal treatment. This means that in this case this process is subject to acceleration related to the rupture of the silicon-silicon bonds and electron excitation in silicon under the influence of the photon flow.","PeriodicalId":122672,"journal":{"name":"Doklady BGUIR","volume":"36 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141204516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}