Subject and Purpose. The paper presents results of numerical modeling and experimental studies of a disk-shaped microstrip antenna involving ‘meander’ type slotted inhomogeneities. The work has been aimed at optimizing the operating range of the antenna and matching it to external circuits through the use of additional structural elements and appropriate feeding techniques. Methods and Methodology. The design features a circular disk-shaped microstrip resonator containing within its plane groups of slotted inhomogeneities which form a segmented meander line, with the segments oriented relative one another at an angle of 120°. The antenna could be fed through a segment of a screened coplanar line. The location of the screening plane of the coplanar line, as well as its dimensions, were variable. Numerical simulation was carried out within the ‘semi-open resonator’ technique using the finite element method. The degree of optimization of the operating range was estimated, based on analyzing spectral characteristics of the antenna, for a variety of its geometric parameters, and the magnitude of the return loss over a given frequency range. Measurements of the VSWR were carried out with reflectometers. Results. Frequency and power characteristics of a monopole, disk-shaped microstrip antenna have been analyzed and optimized over a wide frequency range. Mechanical dimensions of the additional shielding plane and location thereof have been identified as factors having significant influence upon the frequency-dependent, polarizational and power characteristics of the antenna. Conclusions. The operating frequency range, spectral and power characteristics of a monopole, disk-shaped microstrip antenna have been studied both theoretically and experimentally. Numerical simulations were carried out with the use of the fi nite element method. Experimental studies of the frequency characteristics were performed using reflectometry techniques. The antenna considered can find practical application over a wide frequency range, either as a single radiating element in a device or system, or a constituent part of an antenna array.
{"title":"Analysis and Optimization of the Operating Range of a Monopole Antenna Involving ‘Meander’ Type Slot In- homogeneities","authors":"L. Lytvynenko, S. Pogarsky, D. Mayboroda","doi":"10.15407/rpra27.02.083","DOIUrl":"https://doi.org/10.15407/rpra27.02.083","url":null,"abstract":"Subject and Purpose. The paper presents results of numerical modeling and experimental studies of a disk-shaped microstrip antenna involving ‘meander’ type slotted inhomogeneities. The work has been aimed at optimizing the operating range of the antenna and matching it to external circuits through the use of additional structural elements and appropriate feeding techniques. Methods and Methodology. The design features a circular disk-shaped microstrip resonator containing within its plane groups of slotted inhomogeneities which form a segmented meander line, with the segments oriented relative one another at an angle of 120°. The antenna could be fed through a segment of a screened coplanar line. The location of the screening plane of the coplanar line, as well as its dimensions, were variable. Numerical simulation was carried out within the ‘semi-open resonator’ technique using the finite element method. The degree of optimization of the operating range was estimated, based on analyzing spectral characteristics of the antenna, for a variety of its geometric parameters, and the magnitude of the return loss over a given frequency range. Measurements of the VSWR were carried out with reflectometers. Results. Frequency and power characteristics of a monopole, disk-shaped microstrip antenna have been analyzed and optimized over a wide frequency range. Mechanical dimensions of the additional shielding plane and location thereof have been identified as factors having significant influence upon the frequency-dependent, polarizational and power characteristics of the antenna. Conclusions. The operating frequency range, spectral and power characteristics of a monopole, disk-shaped microstrip antenna have been studied both theoretically and experimentally. Numerical simulations were carried out with the use of the fi nite element method. Experimental studies of the frequency characteristics were performed using reflectometry techniques. The antenna considered can find practical application over a wide frequency range, either as a single radiating element in a device or system, or a constituent part of an antenna array.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141368","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}
The paper is dedicated to the memory of Pavel V. Bliokh, an outstanding Ukrainian scientist in the fields of theoretical and radio physics, on the occasion of his 100th anniversary. P.V.Bliokh (PhD, D.Sc, Professor, Honored Scientist of Ukraine) was one of the founders of the ‘space radio physics’ branch of research. While working in that direction, he created a well-known scientific school at the O.Ya Usikov Institute of Radiophysics and Electronics and the Institute of Radio Astronomy, National Academy of Sciences of Ukraine.
{"title":"PAVEL (P.V.) BLIOKH: SCIENTIST AND TEACHER, AND THE FRIEND WE REMEMBER","authors":"V. Sinitsin, Y. Yampolski","doi":"10.15407/rpra27.03.240","DOIUrl":"https://doi.org/10.15407/rpra27.03.240","url":null,"abstract":"The paper is dedicated to the memory of Pavel V. Bliokh, an outstanding Ukrainian scientist in the fields of theoretical and radio physics, on the occasion of his 100th anniversary. P.V.Bliokh (PhD, D.Sc, Professor, Honored Scientist of Ukraine) was one of the founders of the ‘space radio physics’ branch of research. While working in that direction, he created a well-known scientific school at the O.Ya Usikov Institute of Radiophysics and Electronics and the Institute of Radio Astronomy, National Academy of Sciences of Ukraine.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141508","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}
Subject and Purpose. Considered in the paper is diffraction of a plane wave by a structure involving a half-plane and two disks. The disks and the half-plane, lying within parallel planes, are assumed to be infinitely thin and perfectly conducting. The problem is to be analyzed for two cases, namely for that of both disks located on the same side with respect to the half-plane, and for the other where they are placed on opposite sides against the half-plane. The purpose of the paper is to develop a suitable operator method for performing the analysis of the structure described. Methods and Methodology. The solution to the problem has been sought for within the operator method suggested. The electric field components tangential to the half-plane and the disks are expressed, with the aid of Fourier integrals, via some unknown functions having the sense of amplitudes. The unknown amplitudes shall obey the operator equations formulated in terms of wave scattering operators for individual disks and the sole half-plane. Results. When subjected to certain transformations, the operator equations allow obtaining integral equations relative amplitudes of the spherical waves involved. The integral equations permit investigating scattered wave fields for the cases where the disks stay in the shadow region behind the half-plane or in the penumbra, or else in the region which is illuminated by the incident wave. As has been shown, in the case of plane wave scattering at the edge of the half-plane the resulting cylindrical waves possess non-zero amplitudes even with the disks placed totally in the shadow region, hence not illuminated by the incident plane wave. Conclusions. Making use of an operator method, an original solution has been obtained for the problem of plane wave diffraction by a structure consisting of a perfectly conducting, infinitely thin half-plane and two disks. The operator equations of the problem have been shown to be reducible to integral equations, further solvable numerically with the use of discretization based on quadrature rules. The behavior of far and near fields relative to the disks has been studied for a variety of values of the disk radii and their positions relative to the half-plane.
{"title":"AN OPERATOR METHOD FOR THE PROBLEM OF PLANE WAVE DIFFRACTION BY INFINITELY THIN, PERFECTLY CONDUCTING HALF-PLANE AND TWO DISKS","authors":"M. Kaliberda, L. Lytvynenko, S. Pogarsky","doi":"10.15407/rpra27.03.167","DOIUrl":"https://doi.org/10.15407/rpra27.03.167","url":null,"abstract":"Subject and Purpose. Considered in the paper is diffraction of a plane wave by a structure involving a half-plane and two disks. The disks and the half-plane, lying within parallel planes, are assumed to be infinitely thin and perfectly conducting. The problem is to be analyzed for two cases, namely for that of both disks located on the same side with respect to the half-plane, and for the other where they are placed on opposite sides against the half-plane. The purpose of the paper is to develop a suitable operator method for performing the analysis of the structure described. Methods and Methodology. The solution to the problem has been sought for within the operator method suggested. The electric field components tangential to the half-plane and the disks are expressed, with the aid of Fourier integrals, via some unknown functions having the sense of amplitudes. The unknown amplitudes shall obey the operator equations formulated in terms of wave scattering operators for individual disks and the sole half-plane. Results. When subjected to certain transformations, the operator equations allow obtaining integral equations relative amplitudes of the spherical waves involved. The integral equations permit investigating scattered wave fields for the cases where the disks stay in the shadow region behind the half-plane or in the penumbra, or else in the region which is illuminated by the incident wave. As has been shown, in the case of plane wave scattering at the edge of the half-plane the resulting cylindrical waves possess non-zero amplitudes even with the disks placed totally in the shadow region, hence not illuminated by the incident plane wave. Conclusions. Making use of an operator method, an original solution has been obtained for the problem of plane wave diffraction by a structure consisting of a perfectly conducting, infinitely thin half-plane and two disks. The operator equations of the problem have been shown to be reducible to integral equations, further solvable numerically with the use of discretization based on quadrature rules. The behavior of far and near fields relative to the disks has been studied for a variety of values of the disk radii and their positions relative to the half-plane.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141766","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}
Subject and Purpose. The frequency modulation (FM)combined with lock-in detection, the technique which is used in microwave spectroscopy for enhancing the sensitivity of measurements, as well as the effects due to standing wavesinthe measuring absorption cell can lead to distortions in the spectral line shapes observed. To ensure the highest possible accuracy derivable from the experimental data, these distortions needto be taken into account. A way of improving theaccuracy is to approximate to the experimental line contour with a theoretical line shape that would account for the observable distortion effects.The relevant literature sources suggest examples of theoretical expressions for the line shape in the case of a sinusoidal frequency modulation. This work has been aimed at derivingsimilar expressions for the case of a square-wave frequency modulation that shall allow increasing the accuracy of measurements. Methods and Methodology.The square-wave-FM signalsare obtained with the aid of a direct digital frequency synthesizer thatcan provide switching between two frequencies known to a high accuracy. This technical solution permits generating FM signals with precisely specified parameters. Results. A closed-form expression has been suggested, based on numerically evaluated line shape derivatives, whichallows taking into considerationthe basic types of distortions encountered in the spectral line records. The cases that have been considered concern a variety of experimental conditions, including sub-Doppler measurements with Lamb-dip observations. Conclusions. The approach that has been proposed allows one to properly take into account the distortions of spectral line shapes resulting from the use of a square-wave-FM signal, as well as those due to standing wave effects in the spectrometer cell. As has been found, application of this approach to experimental spectra with a variety of modulation parameters permits reducing the errors of frequency determination to ±0.001MHz, provided the signal-to-noise ratios are reasonably high.
{"title":"SQUARE-WAVE FREQUENCY MODULATION IN MICROWAVE SPECTROSCOPY","authors":"E. Alekseev, V. Ilyushin, R. Motiyenko","doi":"10.15407/rpra27.04.299","DOIUrl":"https://doi.org/10.15407/rpra27.04.299","url":null,"abstract":"Subject and Purpose. The frequency modulation (FM)combined with lock-in detection, the technique which is used in microwave spectroscopy for enhancing the sensitivity of measurements, as well as the effects due to standing wavesinthe measuring absorption cell can lead to distortions in the spectral line shapes observed. To ensure the highest possible accuracy derivable from the experimental data, these distortions needto be taken into account. A way of improving theaccuracy is to approximate to the experimental line contour with a theoretical line shape that would account for the observable distortion effects.The relevant literature sources suggest examples of theoretical expressions for the line shape in the case of a sinusoidal frequency modulation. This work has been aimed at derivingsimilar expressions for the case of a square-wave frequency modulation that shall allow increasing the accuracy of measurements. Methods and Methodology.The square-wave-FM signalsare obtained with the aid of a direct digital frequency synthesizer thatcan provide switching between two frequencies known to a high accuracy. This technical solution permits generating FM signals with precisely specified parameters. Results. A closed-form expression has been suggested, based on numerically evaluated line shape derivatives, whichallows taking into considerationthe basic types of distortions encountered in the spectral line records. The cases that have been considered concern a variety of experimental conditions, including sub-Doppler measurements with Lamb-dip observations. Conclusions. The approach that has been proposed allows one to properly take into account the distortions of spectral line shapes resulting from the use of a square-wave-FM signal, as well as those due to standing wave effects in the spectrometer cell. As has been found, application of this approach to experimental spectra with a variety of modulation parameters permits reducing the errors of frequency determination to ±0.001MHz, provided the signal-to-noise ratios are reasonably high.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141984","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}
Subject and Purpose.Methods for computer processing of radio astronomical signals observed with space objects at low frequencies are given. The aim of this paper is to improve the current methods and use their combinations for cleaning records from radio interference of natural and artificial origin in the frequency-time domain, as well as to discuss advantages and disadvantage of the methods. Methods and Methodology.In the study of records obtained with radio astronomical observations there is a common feature of received signals from space sources, which consists in a significant contribution of radio interference. Having sufficient experience on possible types of interference and distortion of signals on the way of their propagation, the efficiency of suggested procedures, clearing radio signal interference in the frequency-time domain by a combination of different approaches in dependence from typical features of signals withinvestigated space objects, is shown. Results. The developed methods of extracting space signals against the background of interference allow one to get unique data on the sources of radio emission in astrophysical phenomena. On the one hand, software tools make it possible to detect very weak events against the background of radio frequency interference. On the other hand, they allow one to measureemission parameters based on the most statistically complete set of events. Conclusions.The results obtained in this work manifest that there is no universal way to overcome any obstacle in the records of radio astronomical observations because of radio interference. In addition, even if the most appropriate method is applied, it often requires pre-adjustment of the corresponding parameters on which the analysis of physical parameters of radio emission in the area of generation depends. But if such a space signal at the radio records is not very spoiled by interference, the use of considered methods can be successful and useful.
{"title":"METHODS OF RADIO FREQUENCY INTERFERENCE MITIGATION ON THE STAGE OF PRELIMINARY PROCESSING OF RECEIVED SIGNALS","authors":"L. Stanislavsky","doi":"10.15407/rpra27.04.268","DOIUrl":"https://doi.org/10.15407/rpra27.04.268","url":null,"abstract":"Subject and Purpose.Methods for computer processing of radio astronomical signals observed with space objects at low frequencies are given. The aim of this paper is to improve the current methods and use their combinations for cleaning records from radio interference of natural and artificial origin in the frequency-time domain, as well as to discuss advantages and disadvantage of the methods. Methods and Methodology.In the study of records obtained with radio astronomical observations there is a common feature of received signals from space sources, which consists in a significant contribution of radio interference. Having sufficient experience on possible types of interference and distortion of signals on the way of their propagation, the efficiency of suggested procedures, clearing radio signal interference in the frequency-time domain by a combination of different approaches in dependence from typical features of signals withinvestigated space objects, is shown. Results. The developed methods of extracting space signals against the background of interference allow one to get unique data on the sources of radio emission in astrophysical phenomena. On the one hand, software tools make it possible to detect very weak events against the background of radio frequency interference. On the other hand, they allow one to measureemission parameters based on the most statistically complete set of events. Conclusions.The results obtained in this work manifest that there is no universal way to overcome any obstacle in the records of radio astronomical observations because of radio interference. In addition, even if the most appropriate method is applied, it often requires pre-adjustment of the corresponding parameters on which the analysis of physical parameters of radio emission in the area of generation depends. But if such a space signal at the radio records is not very spoiled by interference, the use of considered methods can be successful and useful.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141582","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}
Subject and Purpose. The subject of research is the flicker noise present in informant signals of search-and-rescue radars, specifically its properties and the effect it may have on algorithms for detecting and identifying manifestations of human breath and heartbeat processes during rescue operations. The work has been aimed at creating a suitable description of flicker noise for developing optimal algorithms of digital signal processing for quick detection and identification of informant signals during rescue missions. Method and Methodology. The low-frequency flicker noise has been modeled within the polynomial equations technique, proceeding from an analysis of real data on noise components in the output signals from a coherent search-and-rescue radar. A comparative analysis is done for a variety of approximating functions suggested for representing the low frequency portion of the spectrum observed. Results. For the low-frequency range wherein spectral components of the informative signal owing to respiration and heartbeat of humans are concentrated, an adequate model of the fluctuating interference is the flicker noise model built on the basis of polynomial equations. The problem of optimized model representation of the noise in digital signal processing algorithms has been analyzed for the case of a coherent search-and-rescue radar. A model of the fluctuating process has been suggested, based on a polynomial approximation for the spectral function in the low-frequency range of the signals observed at the radar output. Conclusion. Spectral characteristics of both interference and informant signals have been investigated. A structural diagram has been proposed for a high sensitivity, coherent search-and-rescue radar implementing a signal storage algorithm based on the polynomial model of the fluctuating process. The advantages and disadvantages of the radar are discussed, with examples given of real signal implementations and of noise spectrograms. Methods of effective estimation of Doppler signal phases are presented. The paper suggests an analysis of basic requirements as to parameters and performance characteristics of the rescue radar.
{"title":"NOISE FEATURES OF BREATH AND HEARTBEAT INFORMANT SIGNALS","authors":"O. Sytnik","doi":"10.15407/rpra27.04.284","DOIUrl":"https://doi.org/10.15407/rpra27.04.284","url":null,"abstract":"Subject and Purpose. The subject of research is the flicker noise present in informant signals of search-and-rescue radars, specifically its properties and the effect it may have on algorithms for detecting and identifying manifestations of human breath and heartbeat processes during rescue operations. The work has been aimed at creating a suitable description of flicker noise for developing optimal algorithms of digital signal processing for quick detection and identification of informant signals during rescue missions. Method and Methodology. The low-frequency flicker noise has been modeled within the polynomial equations technique, proceeding from an analysis of real data on noise components in the output signals from a coherent search-and-rescue radar. A comparative analysis is done for a variety of approximating functions suggested for representing the low frequency portion of the spectrum observed. Results. For the low-frequency range wherein spectral components of the informative signal owing to respiration and heartbeat of humans are concentrated, an adequate model of the fluctuating interference is the flicker noise model built on the basis of polynomial equations. The problem of optimized model representation of the noise in digital signal processing algorithms has been analyzed for the case of a coherent search-and-rescue radar. A model of the fluctuating process has been suggested, based on a polynomial approximation for the spectral function in the low-frequency range of the signals observed at the radar output. Conclusion. Spectral characteristics of both interference and informant signals have been investigated. A structural diagram has been proposed for a high sensitivity, coherent search-and-rescue radar implementing a signal storage algorithm based on the polynomial model of the fluctuating process. The advantages and disadvantages of the radar are discussed, with examples given of real signal implementations and of noise spectrograms. Methods of effective estimation of Doppler signal phases are presented. The paper suggests an analysis of basic requirements as to parameters and performance characteristics of the rescue radar.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141904","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}
L. Chernogor, K. Garmash, Q. Guo, Y. Luo, V. Rozumenko, Y. Zheng
Subject and Purpose.The study of the effect that each new Solar eclipse (SE) has on radio wave characteristics is an actual scientific and technical issue. The purpose of the present work is to analyze the variations in Doppler spectra (DS), Doppler shift of frequency (DSF), and in the reflected wave amplitude (RWA) that were observed during the SE of June 21, 2020 over the People’s Republic of China. Methods and Methodology.The observations of HF radio wave characteristics were made using the Harbin Engineering University multi-frequency multipath coherent radio system. The temporal variations in DS, DSF of the main ray and RWA are analyzed further. The variations in the Doppler frequency shift (DSF) were subjected to a systematic spectral analysis that involved joint application of the windowed Fourier transform, adaptive Fourier decomposition, and the Morlet mother-function-based wavelet transformation. Results. The SE was accompanied by DS diffuseness resulting from an increase in the number of rays. The DSF temporal variations were observed to be bi-polar and asymmetrical, with extreme DSF magnitudes varying from –11 to –40 mHz and from 22 to 56 mHz. The duration of processes with negative DSF values varied from 50 to 80 min, and the duration of processes with positive DSF changed from 30 to 80 min. The multi-hop propagation (from two to five hops) took place along all propagation paths, with a 360 to 560-km one-hop range. The 4–5-min period quasi-periodic DSF variations showed 20–50 mHz amplitude, and the 8–18-min period variations exhibited 40–100 mHz amplitude. The relative amplitudes of the 4–5 min period quasi-periodic variations in the electron density were observed to be in the 0.3–6.2% range, and the amplitudes of the 8–18 min period variations were found to be in the 1.1–21.7% range. A decrease in the electron density along different propagation paths was observed to vary from –(12–16)% to –(20–26)%.
{"title":"CHARACTERISTIC FEATURES OF VARIATIONS IN HF RADIO WAVE PARAMETERS IN THE IONOSPHERE DURING THE COURSE OF THE SOLAR ECLIPSE OF JUNE 21, 2020 OVER THE PEOPLE’S REPUBLIC OF CHINA","authors":"L. Chernogor, K. Garmash, Q. Guo, Y. Luo, V. Rozumenko, Y. Zheng","doi":"10.15407/rpra27.04.249","DOIUrl":"https://doi.org/10.15407/rpra27.04.249","url":null,"abstract":"Subject and Purpose.The study of the effect that each new Solar eclipse (SE) has on radio wave characteristics is an actual scientific and technical issue. The purpose of the present work is to analyze the variations in Doppler spectra (DS), Doppler shift of frequency (DSF), and in the reflected wave amplitude (RWA) that were observed during the SE of June 21, 2020 over the People’s Republic of China. Methods and Methodology.The observations of HF radio wave characteristics were made using the Harbin Engineering University multi-frequency multipath coherent radio system. The temporal variations in DS, DSF of the main ray and RWA are analyzed further. The variations in the Doppler frequency shift (DSF) were subjected to a systematic spectral analysis that involved joint application of the windowed Fourier transform, adaptive Fourier decomposition, and the Morlet mother-function-based wavelet transformation. Results. The SE was accompanied by DS diffuseness resulting from an increase in the number of rays. The DSF temporal variations were observed to be bi-polar and asymmetrical, with extreme DSF magnitudes varying from –11 to –40 mHz and from 22 to 56 mHz. The duration of processes with negative DSF values varied from 50 to 80 min, and the duration of processes with positive DSF changed from 30 to 80 min. The multi-hop propagation (from two to five hops) took place along all propagation paths, with a 360 to 560-km one-hop range. The 4–5-min period quasi-periodic DSF variations showed 20–50 mHz amplitude, and the 8–18-min period variations exhibited 40–100 mHz amplitude. The relative amplitudes of the 4–5 min period quasi-periodic variations in the electron density were observed to be in the 0.3–6.2% range, and the amplitudes of the 8–18 min period variations were found to be in the 1.1–21.7% range. A decrease in the electron density along different propagation paths was observed to vary from –(12–16)% to –(20–26)%.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141518","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}
I. Ivanchenko, V. Plakhtii, N. Popenko, M. Khruslov
Subject and Purpose. In modern dielectrometry, the problem of detecting foreign inclusions in a radio-transparent material, which are significantly smaller than the operational wavelength, remains very important. The problem becomes even more complicated if it is required to determine complex permittivity of these inclusions. This work analyzes the conditions for the correct use of the original resonance method proposed by the authors earlier for determining permittivity of a local inclusion when its dimensions and dielectric constant change. Methods and Methodology. The measured module consists of a rectangular X-band waveguide, which is partially filled with a dielectric in the form of a rectangular Teflon matrix with a local cubic inclusion inside. The dimensions of the matrix are fixed and are 23 mm × 10 mm × 30 mm. Numerical modeling is performed using the Ansys HFSS software package. The dependences of the resonance frequencies of the module upon changing the dielectric constant of the cube are analyzed. The cube permittivity was changed between 3.8 and 100 in 5-unit steps. Permittivity of the material of the cube is determined by comparing arrays of calculated data with experimental results. Results. Numerical modeling of the module was performed and its electrodynamics properties were determined in the frequency band of 8…10 GHz at different sizes and permittivity of the inclusion. For a cube with a facet size of 2 mm, the resonance frequency decreases with a permittivity increase of the material. For a cube with a facet size of 3 mm and permittivity above 50, additional resonances appear in the structure due to the excitation of resonant modes of the cube itself. Conclusion. It has been shown that by varying the dielectric permittivity of the cubic inset between 3.8 and 100 it proves possible to provide for resonant mode excitation over the frequency range specified. This allows estimating the dielectric permittivity of the cubic inset’s material by way of comparing the calculated versus measured data arrays concerning resonant frequency dependences upon material parameters.
{"title":"RESONANCE PROPERTIES OF AN X-BAND RECTANGULAR WAVEGUIDE SECTION WITH AN INHOMOGENEOUS DIELECTRIC INSET","authors":"I. Ivanchenko, V. Plakhtii, N. Popenko, M. Khruslov","doi":"10.15407/rpra27.02.140","DOIUrl":"https://doi.org/10.15407/rpra27.02.140","url":null,"abstract":"Subject and Purpose. In modern dielectrometry, the problem of detecting foreign inclusions in a radio-transparent material, which are significantly smaller than the operational wavelength, remains very important. The problem becomes even more complicated if it is required to determine complex permittivity of these inclusions. This work analyzes the conditions for the correct use of the original resonance method proposed by the authors earlier for determining permittivity of a local inclusion when its dimensions and dielectric constant change. Methods and Methodology. The measured module consists of a rectangular X-band waveguide, which is partially filled with a dielectric in the form of a rectangular Teflon matrix with a local cubic inclusion inside. The dimensions of the matrix are fixed and are 23 mm × 10 mm × 30 mm. Numerical modeling is performed using the Ansys HFSS software package. The dependences of the resonance frequencies of the module upon changing the dielectric constant of the cube are analyzed. The cube permittivity was changed between 3.8 and 100 in 5-unit steps. Permittivity of the material of the cube is determined by comparing arrays of calculated data with experimental results. Results. Numerical modeling of the module was performed and its electrodynamics properties were determined in the frequency band of 8…10 GHz at different sizes and permittivity of the inclusion. For a cube with a facet size of 2 mm, the resonance frequency decreases with a permittivity increase of the material. For a cube with a facet size of 3 mm and permittivity above 50, additional resonances appear in the structure due to the excitation of resonant modes of the cube itself. Conclusion. It has been shown that by varying the dielectric permittivity of the cubic inset between 3.8 and 100 it proves possible to provide for resonant mode excitation over the frequency range specified. This allows estimating the dielectric permittivity of the cubic inset’s material by way of comparing the calculated versus measured data arrays concerning resonant frequency dependences upon material parameters.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141634","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}
Subject and Purpose. The phase shifters intended for controlling the phase of radio signals are widely used in ultra-high frequency technology, communication systems, radar, and a variety of measuring and special-purpose radio equipment. Designers of phased array antennas face the need of providing for broad beam scanning angles and high antenna gains, which leads to the necessity of greatly increasing the number of array elements, each of which is to be controlled by a phase shifter. Therefore, the development and creation of quick-acting phase shifters is an urgent task. The purpose of this work is to develop high-speed, controllable phase shifters for performing phase angle adjustments and thus provide, at an acceptable cost, for desirable parameters of phased antenna arrays, frequency stabilizing systems of magnetrons, etc. Methods and Methodology. The functional diagram of the proposed quick-acting, controllable phase shifter has been analyzed mathematically and modelled numerically. Results. The controllable phase shifter can be successfully implemented through the use of two parallel-connected resonators at the input of a specific receiver. Analysis of the signal amplitude and phase at the output of the phase shifter in dependence on the values at the input confirms the possibility of adjusting the phase of the output signal over a wide range of angles. Conclusions. A design concept of quick-acting, controllable phase shifters for producing adjustable phase angles has been developed. The device can be employed in phased antenna arrays or frequency stabilizing systems as a means of improving their operation parameters and reducing their cost at that.
{"title":"QUICK-ACTING, CONTROLLABLE PHASE SHIFTER FOR PHASE ANGLE ADJUSTMENT IN RADIO SIGNALS","authors":"I. Mytsenko, O. Roenko","doi":"10.15407/rpra27.03.213","DOIUrl":"https://doi.org/10.15407/rpra27.03.213","url":null,"abstract":"Subject and Purpose. The phase shifters intended for controlling the phase of radio signals are widely used in ultra-high frequency technology, communication systems, radar, and a variety of measuring and special-purpose radio equipment. Designers of phased array antennas face the need of providing for broad beam scanning angles and high antenna gains, which leads to the necessity of greatly increasing the number of array elements, each of which is to be controlled by a phase shifter. Therefore, the development and creation of quick-acting phase shifters is an urgent task. The purpose of this work is to develop high-speed, controllable phase shifters for performing phase angle adjustments and thus provide, at an acceptable cost, for desirable parameters of phased antenna arrays, frequency stabilizing systems of magnetrons, etc. Methods and Methodology. The functional diagram of the proposed quick-acting, controllable phase shifter has been analyzed mathematically and modelled numerically. Results. The controllable phase shifter can be successfully implemented through the use of two parallel-connected resonators at the input of a specific receiver. Analysis of the signal amplitude and phase at the output of the phase shifter in dependence on the values at the input confirms the possibility of adjusting the phase of the output signal over a wide range of angles. Conclusions. A design concept of quick-acting, controllable phase shifters for producing adjustable phase angles has been developed. The device can be employed in phased antenna arrays or frequency stabilizing systems as a means of improving their operation parameters and reducing their cost at that.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141381","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}
S. Prosvirnin, V. Khardikov, V. Yachin, V. Plakhtii, N. Sydorchuk
Subject and Purpose. Theoretical demonstration of controllable features of a non-conventional resonant back reflection of light, realizable with the aid of a structured silicon-on-metal covering. Methods and Methodology. The investigation has been performed through a full-wave numerical simulation in a finite-element technique. Results. The nonlinear optical properties of a planar structure, involving a set of silicon disks disposed periodically on a silver substrate, have been studied in the Littrow scenario of wave reflection. The structure manifests a bistable resonant reflectivity property. The magnitudes of both specular and back reflection ratios can be controlled by means of varying the incident light intensity. Conclusions. An array of identical silicon disks, placed in a periodic order on a silver substrate, can be employed as an efficiently excitable and tunable nonlinear resonant reflective structure implementing Littrow’s non-specular diffraction scenario. As has been found, the effect of nonlinear response from the silicon disks can be used for implementing a regimen of bistable back reflection, controllable by means of varying the incident wave’s intensity. The nonlinear tunability of the silicon-on-silver structure does promise extensions of the operation area of classical metamaterials of sub-wavelength scale sizes as it offers new
{"title":"INTENSITY CONTROLLED, NONSPECULAR RESONANT BACK REFLECTION OF LIGHT","authors":"S. Prosvirnin, V. Khardikov, V. Yachin, V. Plakhtii, N. Sydorchuk","doi":"10.15407/rpra27.03.181","DOIUrl":"https://doi.org/10.15407/rpra27.03.181","url":null,"abstract":"Subject and Purpose. Theoretical demonstration of controllable features of a non-conventional resonant back reflection of light, realizable with the aid of a structured silicon-on-metal covering. Methods and Methodology. The investigation has been performed through a full-wave numerical simulation in a finite-element technique. Results. The nonlinear optical properties of a planar structure, involving a set of silicon disks disposed periodically on a silver substrate, have been studied in the Littrow scenario of wave reflection. The structure manifests a bistable resonant reflectivity property. The magnitudes of both specular and back reflection ratios can be controlled by means of varying the incident light intensity. Conclusions. An array of identical silicon disks, placed in a periodic order on a silver substrate, can be employed as an efficiently excitable and tunable nonlinear resonant reflective structure implementing Littrow’s non-specular diffraction scenario. As has been found, the effect of nonlinear response from the silicon disks can be used for implementing a regimen of bistable back reflection, controllable by means of varying the incident wave’s intensity. The nonlinear tunability of the silicon-on-silver structure does promise extensions of the operation area of classical metamaterials of sub-wavelength scale sizes as it offers new","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141779","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：