G. Ermak, A. Vasilev, A. Varavin, M. Balaban, A. Fateev, V. Zheltov
Subject and Purpose. In Part 1 of the paper, a mathematical model of an autodyne self-oscillator with frequency tuning by varactor capacitance varying is built and thoroughly analyzed for the features of signal formation in autodyne radar with a wide frequency-modulation bandwidth and a nonlinearity in the modulation characteristic. The aim of the study is to appreciate the action that the nonlinearity of the oscillator modulation characteristic exerts on the spectral characteristics of signals from frequency-modulation autodyne radar. Methods and Methodology. The research method is a mathematical analysis of the operation of an autodyne oscillator with electronic frequency tuning. To examine formation processes of emitted autodyne signals, the spectral, frequency and amplitude characteristics of signals from frequency-modulation autodyne radar are constructed with the use of numerical modeling techniques. Results. Numerical modeling of autodyne response signal spectra has been performed for various distances to the reflecting object and different modulating voltages across the varactor. It has been shown that a nonlinear dependence of the generator frequency on the varactor voltage makes for the broadening of the autodyne response signal spectrum. It has been found that as the object distance increases, the frequency of the autodyne response signal moves towards the higher frequencies, while the nonlinearity makes the spectrum broaden. The obtained calculation results refer to an 8-mm Gunn diode autodyne. Conclusion. The performed research of the spectral characteristics and into the features of signal formation in autodyne transceiver devices with a wide frequency tuning has shown that in order to achieve high resolution figures from autodyne radar, certain methods are needed to be developed for adjusting the laws of frequency modulation and for the processing of response signals from reflecting objects. Such a method and ways to solve these problems will be presented in Part 2 of the work.
{"title":"SIGNAL FORMATION AND PROCESSING FEATURES FROM AUTODYNE RADAR WITH A WIDE FREQUENCY MODULATION BAND. (РART 1)","authors":"G. Ermak, A. Vasilev, A. Varavin, M. Balaban, A. Fateev, V. Zheltov","doi":"10.15407/rpra27.01.053","DOIUrl":"https://doi.org/10.15407/rpra27.01.053","url":null,"abstract":"Subject and Purpose. In Part 1 of the paper, a mathematical model of an autodyne self-oscillator with frequency tuning by varactor capacitance varying is built and thoroughly analyzed for the features of signal formation in autodyne radar with a wide frequency-modulation bandwidth and a nonlinearity in the modulation characteristic. The aim of the study is to appreciate the action that the nonlinearity of the oscillator modulation characteristic exerts on the spectral characteristics of signals from frequency-modulation autodyne radar. Methods and Methodology. The research method is a mathematical analysis of the operation of an autodyne oscillator with electronic frequency tuning. To examine formation processes of emitted autodyne signals, the spectral, frequency and amplitude characteristics of signals from frequency-modulation autodyne radar are constructed with the use of numerical modeling techniques. Results. Numerical modeling of autodyne response signal spectra has been performed for various distances to the reflecting object and different modulating voltages across the varactor. It has been shown that a nonlinear dependence of the generator frequency on the varactor voltage makes for the broadening of the autodyne response signal spectrum. It has been found that as the object distance increases, the frequency of the autodyne response signal moves towards the higher frequencies, while the nonlinearity makes the spectrum broaden. The obtained calculation results refer to an 8-mm Gunn diode autodyne. Conclusion. The performed research of the spectral characteristics and into the features of signal formation in autodyne transceiver devices with a wide frequency tuning has shown that in order to achieve high resolution figures from autodyne radar, certain methods are needed to be developed for adjusting the laws of frequency modulation and for the processing of response signals from reflecting objects. Such a method and ways to solve these problems will be presented in Part 2 of the work.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45080309","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}
А. М. Linkova, A. Mogyla, H. Rudnev, V. Kantsedal, S. Khomenko
Subject and Purpose. Th e development of radar methods for measuring liquid-drop precipitation characteristics is of great importance for studying physical processes in the atmosphere and for lots of applied problems to be solved. At the same time, an experimental research of these methods in situ is essential to determine their frames and scope and estimate retrieval errors of the rain parameters. The purpose of the work is to evaluate eff ectiveness of the previously proposed method that is based on the parametrization of the distribution function of drops by size, uses averaged touch-probing data of the three-parameter gamma distribution of the parameters versus the rain intensity, and employs the double-frequency method of precipitation remote sensing. For its validation, the rain intensity results obtained by the radar sensing are compared with the data taken from the ground raingauge. Methods and Methodology. Th e measurement results gained by the proposed method are compared with the measurement results obtained by the standard technique. Results. An experimental study using the previously developed algorithm and with a refi ned double-frequency weather radar MRL-1 has been given to the double-frequency sensing of liquid-drop precipitation. Th e obtained results show that the proposed data processing algorithm for double-frequency sensing of liquid-drop precipitation is good at the rain intensity retrieval and makes it possible to estimate liquid precipitation amounts over long periods of time. Conclusion. Th e rain intensity measured with the use of meteo radar almost completely coincides, both qualitatively and quantitatively, with the data from the ground raingauge. Th e algorithm proposed by the authors for processing double-frequency radar sensing data on liquid-drop precipitation retrieves the rain intensity and, also, evaluates liquid-drop precipitation amounts.
{"title":"VALIDATION OF REMOTE MEASUREMENT OF RAIN CHARACTERISTICS BY THE METHOD OF DOUBLE FREQUENCY RADAR SENSING","authors":"А. М. Linkova, A. Mogyla, H. Rudnev, V. Kantsedal, S. Khomenko","doi":"10.15407/rpra27.01.038","DOIUrl":"https://doi.org/10.15407/rpra27.01.038","url":null,"abstract":"Subject and Purpose. Th e development of radar methods for measuring liquid-drop precipitation characteristics is of great importance for studying physical processes in the atmosphere and for lots of applied problems to be solved. At the same time, an experimental research of these methods in situ is essential to determine their frames and scope and estimate retrieval errors of the rain parameters. The purpose of the work is to evaluate eff ectiveness of the previously proposed method that is based on the parametrization of the distribution function of drops by size, uses averaged touch-probing data of the three-parameter gamma distribution of the parameters versus the rain intensity, and employs the double-frequency method of precipitation remote sensing. For its validation, the rain intensity results obtained by the radar sensing are compared with the data taken from the ground raingauge. Methods and Methodology. Th e measurement results gained by the proposed method are compared with the measurement results obtained by the standard technique. Results. An experimental study using the previously developed algorithm and with a refi ned double-frequency weather radar MRL-1 has been given to the double-frequency sensing of liquid-drop precipitation. Th e obtained results show that the proposed data processing algorithm for double-frequency sensing of liquid-drop precipitation is good at the rain intensity retrieval and makes it possible to estimate liquid precipitation amounts over long periods of time. Conclusion. Th e rain intensity measured with the use of meteo radar almost completely coincides, both qualitatively and quantitatively, with the data from the ground raingauge. Th e algorithm proposed by the authors for processing double-frequency radar sensing data on liquid-drop precipitation retrieves the rain intensity and, also, evaluates liquid-drop precipitation amounts.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47710755","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. Th e study of the eff ect of refl ectionless electromagnetic waves propagation through solid-state structures containing metasurfaces at its boundaries has a great scientifi c and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Th e aim of this work is to study the eff ect of an anisotropic uniaxial plasmon metasurface located at the boundary of the dielectric layer on the eff ect of refl ectionless propagation of electromagnetic waves. The study of the effect of refl ectionless propagation of electromagnetic waves through solid-state structures containing metasurfaces at its boundaries is of great scientific and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Methods and Methodology. Numerical simulations were used to study the effect of the refl ectionless electromagnetic waves propagation through an anisotropic uniaxial plasma metasurface lying on the dielectric layer. It is used to determine the thicknesses and permeability values of the dielectric layer, for which the effect was observed. Results. It is shown that the presence of an anisotropic uniaxial plasmon metasurface on the dielectric layer leads to a signifi cant conditions change of the eff ect of refl ectionless propagation of p-polarized electromagnetic waves along and across the main axis of anisotropy of the metasurface. It was shown that the metasurface removes the rigid restriction of the dielectric layer permeability value. To achieve the effect of refl ectionless propagation of electromagnetic waves, the permeability of the dielectric layer can be chosen within a wide range. Conclusion. Dielectric layers with anisotropic uniaxial plasmonic metasurfaces have signifi cantly better characteristics for the effect of refl ectionless propagation of electromagnetic waves. They can be used to create fundamentally new nanoelectronic and optical devices.
{"title":"INFLUENCE OF UNIAXIAL PLASMON METASURFACE ON ANTIREFLECTION PROPERTIES OF DIELECTRIC LAYER","authors":"M. Beletskii, І. D. Popovych","doi":"10.15407/rpra27.01.075","DOIUrl":"https://doi.org/10.15407/rpra27.01.075","url":null,"abstract":"Subject and Purpose. Th e study of the eff ect of refl ectionless electromagnetic waves propagation through solid-state structures containing metasurfaces at its boundaries has a great scientifi c and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Th e aim of this work is to study the eff ect of an anisotropic uniaxial plasmon metasurface located at the boundary of the dielectric layer on the eff ect of refl ectionless propagation of electromagnetic waves. The study of the effect of refl ectionless propagation of electromagnetic waves through solid-state structures containing metasurfaces at its boundaries is of great scientific and practical interest for improving the performance and creating new types of nanoelectronics and optics devices. Methods and Methodology. Numerical simulations were used to study the effect of the refl ectionless electromagnetic waves propagation through an anisotropic uniaxial plasma metasurface lying on the dielectric layer. It is used to determine the thicknesses and permeability values of the dielectric layer, for which the effect was observed. Results. It is shown that the presence of an anisotropic uniaxial plasmon metasurface on the dielectric layer leads to a signifi cant conditions change of the eff ect of refl ectionless propagation of p-polarized electromagnetic waves along and across the main axis of anisotropy of the metasurface. It was shown that the metasurface removes the rigid restriction of the dielectric layer permeability value. To achieve the effect of refl ectionless propagation of electromagnetic waves, the permeability of the dielectric layer can be chosen within a wide range. Conclusion. Dielectric layers with anisotropic uniaxial plasmonic metasurfaces have signifi cantly better characteristics for the effect of refl ectionless propagation of electromagnetic waves. They can be used to create fundamentally new nanoelectronic and optical devices.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49508423","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 existing interest in nanosized magnetic materials requires equipment for express post-synthesis measurements of magnetic properties of these nanostructures in such a way as to exclude any mechanical displacement of the sample. Although there exist plenty of methods and devices for studying magnetic properties of materials, the development of novel schemes based on the known techniques for examining properties of magnetic nanomaterials, for example magnetic nanopowders, is a hot problem. Th e measurement equipment of the sort will detect changes in the magnetic properties of materials over time and under the infl uence of various factors, such as temperature, external magnetic fi elds, stabilizing substances. Method and Methodology. The developed setup for registering magnetic hysteresis loops is based on the method of small perturbations performed by an alternating magnetic fi eld. The devised scheme combines conventional physical principles of both hysterometers and vibrating-sample magnetometers. Results. With the aid of the developed setup, magnetic hysteresis loops of La 0.775 Sr 0.225 MnO3 nanopowder have been obtained and compared with the data provided by the well-known technique. A good agreement was observed. Th e measurement error was 10%. Conclusion. The suggested scheme can be used for the express registration of magnetic hysteresis loops of miscellaneous magnetic materials of various compositions, including nanoscale magnets.
主题和目的。现有的对纳米磁性材料的兴趣需要设备来快速测量这些纳米结构的合成后磁性，以排除样品的任何机械位移。虽然研究材料磁性能的方法和装置很多，但是基于已知的磁性纳米材料(如磁性纳米粉末)的磁性能检测方法的开发是一个热点问题。这种测量设备将检测材料在温度、外部磁场、稳定物质等各种因素影响下的磁性随时间的变化。方法和方法论。所开发的磁滞回线记录装置是基于交变磁场的小扰动方法。所设计的方案结合了传统的磁滞计和振动样品磁强计的物理原理。结果。利用所建立的装置，得到了La 0.775 Sr 0.225 MnO3纳米粉体的磁滞回线，并与已知技术提供的数据进行了比较。大家达成了很好的协议。测量误差为10%。结论。所提出的方案可用于包括纳米级磁体在内的各种成分的杂磁材料的磁滞回线的快速配准。
{"title":"A STRING MAGNETOMETER USING THE METHOD OF SMALL PERTURBATIONS","authors":"K. Sova, A. Vakula, E. Chernyakov, S. Tarapov","doi":"10.15407/rpra27.01.048","DOIUrl":"https://doi.org/10.15407/rpra27.01.048","url":null,"abstract":"Subject and Purpose. The existing interest in nanosized magnetic materials requires equipment for express post-synthesis measurements of magnetic properties of these nanostructures in such a way as to exclude any mechanical displacement of the sample. Although there exist plenty of methods and devices for studying magnetic properties of materials, the development of novel schemes based on the known techniques for examining properties of magnetic nanomaterials, for example magnetic nanopowders, is a hot problem. Th e measurement equipment of the sort will detect changes in the magnetic properties of materials over time and under the infl uence of various factors, such as temperature, external magnetic fi elds, stabilizing substances. Method and Methodology. The developed setup for registering magnetic hysteresis loops is based on the method of small perturbations performed by an alternating magnetic fi eld. The devised scheme combines conventional physical principles of both hysterometers and vibrating-sample magnetometers. Results. With the aid of the developed setup, magnetic hysteresis loops of La 0.775 Sr 0.225 MnO3 nanopowder have been obtained and compared with the data provided by the well-known technique. A good agreement was observed. Th e measurement error was 10%. Conclusion. The suggested scheme can be used for the express registration of magnetic hysteresis loops of miscellaneous magnetic materials of various compositions, including nanoscale magnets.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46142970","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}
Purpose. The object of the study are electron density depletions (‘holes’) occurring in the ionospheric F-region under the action of rocket exhaust products. The purpose is to present and discuss the results of observations concerning the ionospheric holes that were detected in the course of a number of launches of medium-lift Kosmos vehicles from the Kapustin Yar spaceport. Nei- ther that cosmodrome, nor the rocket type had been subjects of similar analysis before. Design/methodology/approach. The observations at the Kapustin Yar cosmodrome were performed with a portable vertical Doppler sounder. The beats between a reference signal and the one reflected from the ionosphere were subjected to spectral analysis, which allowed identifying the principal mode of the Doppler frequency shift and establishing time dependences of that frequency shift. An ionosonde located nearby was used for monitoring the underlying state of the ionosphere. Findings. The measurements performed with the vertical Doppler sounder near the launch site of the medium-lift Kosmos rocket have allowed obtaining first estimates for the principal parameters of the ionospheric holes arising in the F-region along the vehicle trajectory, as well as for the accompanying quasi-periodic variations in the electron density. The spatial scale sizes of the holes have been found to be in excess of 300 km, while the electron density reductions may attain » 50 %. These results are in agreement with the data obtained by international researchers for effects from heavy- and super heavy-lift launch vehicles. Also, note that the types of propellant differed significantly. The propagation velocity of the hole’s front edge was estimated to be » 140 m/s. The hole formation was accompanied by quasi-periodic variations in the Doppler frequency shift as a result of radar signal scattering from the electron density fluctuations produced by propagating atmospheric gravity- and infrasonic waves. The atmospheric gravity waves showed periods in the range from 7 to 20 minutes, and the infrasonic waves had a period close to 2 min. The amplitudes of quasi-periodic electron density variations were estimated for the two modes to be » 0.3 ¸1.5 % and » 0.02 ¸ 0.03 %, respectively. Conclusions. Medium-lift launch vehicles (mass of a few hundred tons) are capable of forming ionospheric ‘holes’ of several hundred kilometers in size and of reducing the electron density in the F-region by a factor greater than 2.
{"title":"LARGE-SCALE REDUCTIONS IN THE ELECTRON DENSITY OF IONOSPHERIC F-REGION, OBSERVABLE ALONG ROCKET TRAJECTORIES AT LAUNCH","authors":"L. Chernogor","doi":"10.15407/rpra27.01.026","DOIUrl":"https://doi.org/10.15407/rpra27.01.026","url":null,"abstract":"Purpose. The object of the study are electron density depletions (‘holes’) occurring in the ionospheric F-region under the action of rocket exhaust products. The purpose is to present and discuss the results of observations concerning the ionospheric holes that were detected in the course of a number of launches of medium-lift Kosmos vehicles from the Kapustin Yar spaceport. Nei- ther that cosmodrome, nor the rocket type had been subjects of similar analysis before. Design/methodology/approach. The observations at the Kapustin Yar cosmodrome were performed with a portable vertical Doppler sounder. The beats between a reference signal and the one reflected from the ionosphere were subjected to spectral analysis, which allowed identifying the principal mode of the Doppler frequency shift and establishing time dependences of that frequency shift. An ionosonde located nearby was used for monitoring the underlying state of the ionosphere. Findings. The measurements performed with the vertical Doppler sounder near the launch site of the medium-lift Kosmos rocket have allowed obtaining first estimates for the principal parameters of the ionospheric holes arising in the F-region along the vehicle trajectory, as well as for the accompanying quasi-periodic variations in the electron density. The spatial scale sizes of the holes have been found to be in excess of 300 km, while the electron density reductions may attain » 50 %. These results are in agreement with the data obtained by international researchers for effects from heavy- and super heavy-lift launch vehicles. Also, note that the types of propellant differed significantly. The propagation velocity of the hole’s front edge was estimated to be » 140 m/s. The hole formation was accompanied by quasi-periodic variations in the Doppler frequency shift as a result of radar signal scattering from the electron density fluctuations produced by propagating atmospheric gravity- and infrasonic waves. The atmospheric gravity waves showed periods in the range from 7 to 20 minutes, and the infrasonic waves had a period close to 2 min. The amplitudes of quasi-periodic electron density variations were estimated for the two modes to be » 0.3 ¸1.5 % and » 0.02 ¸ 0.03 %, respectively. Conclusions. Medium-lift launch vehicles (mass of a few hundred tons) are capable of forming ionospheric ‘holes’ of several hundred kilometers in size and of reducing the electron density in the F-region by a factor greater than 2.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47993901","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. Designers of the research radars intended for detecting manifestations of biological activity of living organisms may be interested in the noise characteristics shown by their oscillators at offsets about 10–2 Hz or even 10–3Hz from the carrier frequency. Unfortunately, the producing companies do not practice regular information on noise performance of their products at frequencies below 1 Hz. The present authors have set the goal of deriving an analytical expression for the spectral density of flicker noise which should allow radar engineers estimating the probable noise performance of low-noise oscillators over any frequency range. Methods and Methodology. A great number of writers considering spectral properties of flicker noise tend to support the assertion that its spectral density increases continuously with a decrease in frequency, following the power law 1/f . Meanwhile, the present authors assume availability of a certain frequencyfmbelow which the spectral density should most likely remain unchanged, even to as low as zero frequency. Also, there is a range of frequencies above which the spectral density of flicker noise remains constant and the total spectral density is determined solely by thermal noise. Results.The spectral density of noise follows the power law 1/f throughout the range fromfm and up to the point where thermal noise starts to overbalance the flicker noise. The authors have proposed an approximating function to describe the behavior of the averaged spectral density of noise from the oscillator within the entire frequency range. Conclusions. The results obtained shall allow radio system designers to make estimates of the probable noise performance of low-noise oscillators in any frequency range, using only known reference data provided by the manufacturer.
{"title":"ESTIMATING THE SPECTRAL DENSITY OF FLICKER NOISE OF LOW-NOISE OSCILLATORS AT INFRA-LOW FREQUENCIES","authors":"V. Konovalov, K. Lukin","doi":"10.15407/rpra27.03.229","DOIUrl":"https://doi.org/10.15407/rpra27.03.229","url":null,"abstract":"Subject and Purpose. Designers of the research radars intended for detecting manifestations of biological activity of living organisms may be interested in the noise characteristics shown by their oscillators at offsets about 10–2 Hz or even 10–3Hz from the carrier frequency. Unfortunately, the producing companies do not practice regular information on noise performance of their products at frequencies below 1 Hz. The present authors have set the goal of deriving an analytical expression for the spectral density of flicker noise which should allow radar engineers estimating the probable noise performance of low-noise oscillators over any frequency range. Methods and Methodology. A great number of writers considering spectral properties of flicker noise tend to support the assertion that its spectral density increases continuously with a decrease in frequency, following the power law 1/f . Meanwhile, the present authors assume availability of a certain frequencyfmbelow which the spectral density should most likely remain unchanged, even to as low as zero frequency. Also, there is a range of frequencies above which the spectral density of flicker noise remains constant and the total spectral density is determined solely by thermal noise. Results.The spectral density of noise follows the power law 1/f throughout the range fromfm and up to the point where thermal noise starts to overbalance the flicker noise. The authors have proposed an approximating function to describe the behavior of the averaged spectral density of noise from the oscillator within the entire frequency range. Conclusions. The results obtained shall allow radio system designers to make estimates of the probable noise performance of low-noise oscillators in any frequency range, using only known reference data provided by the manufacturer.","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":"67141434","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 unique natural phenomena which solar eclipses are can activate coupling between the subsystems of the Earth–atmosphere–ionosphere–magnetosphere system. Following an eclipse, disturbances may get induced in all the subsystems and their associated geophysical fields. It is important that a subsystem’s response does not depend on the phase of the eclipse alone, but also on the state of space weather and the observation site coordinates. The majority of solar eclipses occur at middle and low latitudes. The maximum phase of the June 10, 2021 annular eclipse was observed at high latitudes, including the North Pole. The highlatitude ionosphere is fundamentally different from the mid- and low-latitude ionosphere as it stays in a metastable state, such that any impact may be capable of activating subsystem coupling. The relevance of this study is conditioned by the diversity of the solar eclipse effects in the high-latitude ionosphere. The purpose of this work is to present observational results concerning variations in the total electron content (TEC) in the high-latitude ionosphere in the course of the June 10, 2021 solar eclipse. Methods and Methodology. An array of eleven terrestrial GPS receive stations and eight GPS satellites were used for the observations. Results. The effects from the solar eclipse were distinctly observable at all eleven reception sites and from all the eight satellites. On the average, i.e. with random fluctuations neglected, changes in illumination at ionospheric heights were followed by decreases in the TEC. All of the observation records demonstrated a decrease in the TEC at the early stage of the eclipse. Some 60 to 100 min later the TEC attained a minimum and then returned to virtually the initial value. The lowest observed magnitude of the TEC was 1.0–5.1 TEC units, while, on the average, it was found to be 2.7 ± 1.6 TEC units, or 35 ± 18%. The greatest decrease in the TEC lagged behind the maximum phase of the solar eclipse (lowest illumination at the heights of the ionosphere) by 5–30 min, or 15.7 ± 6.8 min on the average. A few TEC records obtained at different stations showed quasi-periodic variations with the periods ranging from 5 to 19 min and amplitudes of 1 to 12%. Conclusions. The annular eclipse of June 10, 2021 acted to significantly disturb the high-latitude ionosphere where aperiodic and quasi-periodic disturbances of the TEC took place.
{"title":"EFFECTS FROM THE JUNE 10, 2021 SOLAR ECLIPSE IN THE HIGH-LATITUDE IONOSPHERE: RESULTS OF GPS OBSERVATIONS","authors":"L. Chernogor, Y. Mylovanov, Y. Luo","doi":"10.15407/rpra27.02.093","DOIUrl":"https://doi.org/10.15407/rpra27.02.093","url":null,"abstract":"Subject and Purpose. The unique natural phenomena which solar eclipses are can activate coupling between the subsystems of the Earth–atmosphere–ionosphere–magnetosphere system. Following an eclipse, disturbances may get induced in all the subsystems and their associated geophysical fields. It is important that a subsystem’s response does not depend on the phase of the eclipse alone, but also on the state of space weather and the observation site coordinates. The majority of solar eclipses occur at middle and low latitudes. The maximum phase of the June 10, 2021 annular eclipse was observed at high latitudes, including the North Pole. The highlatitude ionosphere is fundamentally different from the mid- and low-latitude ionosphere as it stays in a metastable state, such that any impact may be capable of activating subsystem coupling. The relevance of this study is conditioned by the diversity of the solar eclipse effects in the high-latitude ionosphere. The purpose of this work is to present observational results concerning variations in the total electron content (TEC) in the high-latitude ionosphere in the course of the June 10, 2021 solar eclipse. Methods and Methodology. An array of eleven terrestrial GPS receive stations and eight GPS satellites were used for the observations. Results. The effects from the solar eclipse were distinctly observable at all eleven reception sites and from all the eight satellites. On the average, i.e. with random fluctuations neglected, changes in illumination at ionospheric heights were followed by decreases in the TEC. All of the observation records demonstrated a decrease in the TEC at the early stage of the eclipse. Some 60 to 100 min later the TEC attained a minimum and then returned to virtually the initial value. The lowest observed magnitude of the TEC was 1.0–5.1 TEC units, while, on the average, it was found to be 2.7 ± 1.6 TEC units, or 35 ± 18%. The greatest decrease in the TEC lagged behind the maximum phase of the solar eclipse (lowest illumination at the heights of the ionosphere) by 5–30 min, or 15.7 ± 6.8 min on the average. A few TEC records obtained at different stations showed quasi-periodic variations with the periods ranging from 5 to 19 min and amplitudes of 1 to 12%. Conclusions. The annular eclipse of June 10, 2021 acted to significantly disturb the high-latitude ionosphere where aperiodic and quasi-periodic disturbances of the TEC took place.","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":"67141406","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 paper is an effectiveness study of the root-MUSIC technique as applied to elevation angle measurements of low-altitude radar targets over the sea, specifically with account of the radio waves’ phase front sphericity. The purpose is to find out whether and how much can the measurement accuracy be improved through account of the phase front sphericity, as compared with the classical approach assuming a plane phase front. Methods and Methodology. The work proceeds from computer simulation, considering a variety of sea roughness levels, and covers a range of radio wave reflection conditions from a nearly specular return to strong diff use reflection from the sea surface. The simulation involves a wide range of target distances within the far-field region with respect to the receive array. Results. A new approach has been suggested for taking into account the phase-front sphericity of the radio waves arriving from the target. The level of errors of elevation angle measurements has been estimated and compared with such shown by the conventional root-MUSIC method which assumes a plane phase front for the waves reflected from the target. The comparison concerns a wide range of sea roughness levels and target separations. Conclusion. It has been established that the proposed version of the root-MUSIC technique which takes wave front sphericity into account can significantly reduce the errors in elevation angle measurements for low-altitude targets.
{"title":"ROOT-MUSIC MEASUREMENTS OF TARGET ELEVATION ANGLES WITH ACCOUNT OF RADIO WAVE’S PHASE FRONT SPHERICITY","authors":"Y. Pedenko","doi":"10.15407/rpra27.02.110","DOIUrl":"https://doi.org/10.15407/rpra27.02.110","url":null,"abstract":"Subject and Purpose. The paper is an effectiveness study of the root-MUSIC technique as applied to elevation angle measurements of low-altitude radar targets over the sea, specifically with account of the radio waves’ phase front sphericity. The purpose is to find out whether and how much can the measurement accuracy be improved through account of the phase front sphericity, as compared with the classical approach assuming a plane phase front. Methods and Methodology. The work proceeds from computer simulation, considering a variety of sea roughness levels, and covers a range of radio wave reflection conditions from a nearly specular return to strong diff use reflection from the sea surface. The simulation involves a wide range of target distances within the far-field region with respect to the receive array. Results. A new approach has been suggested for taking into account the phase-front sphericity of the radio waves arriving from the target. The level of errors of elevation angle measurements has been estimated and compared with such shown by the conventional root-MUSIC method which assumes a plane phase front for the waves reflected from the target. The comparison concerns a wide range of sea roughness levels and target separations. Conclusion. It has been established that the proposed version of the root-MUSIC technique which takes wave front sphericity into account can significantly reduce the errors in elevation angle measurements for low-altitude targets.","PeriodicalId":33380,"journal":{"name":"Radio Physics and Radio Astronomy","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67141472","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 analysis of the electromagnetic waves’ polarizational transformations that may accompany their reflection from a metasurface is of considerable scientific and practical interest from the point of possibilities for improving characteristics of nanoelectronic and optical devices, and creating novel types of these. This work has been aimed at finding the conditions for efficient conversion of a p-polarized electromagnetic wave incident upon a uniaxial plasmonic metasurface at the boundary of a dielectric layer, into a wave of s-polarization. Methods and Methodology. The effects of conversion of p-polarized electromagnetic waves incident upon a uniaxial plasmonic metasurface, into s-polarized waves were explored through numerical modeling. The approach has allowed determining the wave frequencies and thicknesses of the dielectric layer best suitable for ensuring full conversion. Results. The presence of a uniaxial plasmonic metasurface on top of a dielectric layer can provide for full conversion of an incident p-polarized electromagnetic wave into a wave of s-polarization. As has been established, the effect takes place if the plane of incidence of the p-polarized wave makes an acute angle with the principal axis of the plasmonic metasurface. Another finding is that the full conversion is possible for a variety of permittivity values of the dielectric layer. Conclusions. The uniaxial plasmonic metasurface placed on a dielectric layer is characterized by unique reflective properties. It can have a noticeable impact on polarization of the p-polarized wave’s incident upon the layer. Dielectric layers provided with uniaxial metasurfaces can be used for creating optical and nanoelectronic devices of new types.
{"title":"CHANGES IN ELECTROMAGNETIC WAVE POLARIZATION RESULTING FROM ITS REFLECTION AT A UNIAXIAL PLASMONIC METASURFACE ON TOP OF A DIELECTRIC LAYER","authors":"M. Beletskii, I. Popovych","doi":"10.15407/rpra27.02.153","DOIUrl":"https://doi.org/10.15407/rpra27.02.153","url":null,"abstract":"Subject and Purpose. The analysis of the electromagnetic waves’ polarizational transformations that may accompany their reflection from a metasurface is of considerable scientific and practical interest from the point of possibilities for improving characteristics of nanoelectronic and optical devices, and creating novel types of these. This work has been aimed at finding the conditions for efficient conversion of a p-polarized electromagnetic wave incident upon a uniaxial plasmonic metasurface at the boundary of a dielectric layer, into a wave of s-polarization. Methods and Methodology. The effects of conversion of p-polarized electromagnetic waves incident upon a uniaxial plasmonic metasurface, into s-polarized waves were explored through numerical modeling. The approach has allowed determining the wave frequencies and thicknesses of the dielectric layer best suitable for ensuring full conversion. Results. The presence of a uniaxial plasmonic metasurface on top of a dielectric layer can provide for full conversion of an incident p-polarized electromagnetic wave into a wave of s-polarization. As has been established, the effect takes place if the plane of incidence of the p-polarized wave makes an acute angle with the principal axis of the plasmonic metasurface. Another finding is that the full conversion is possible for a variety of permittivity values of the dielectric layer. Conclusions. The uniaxial plasmonic metasurface placed on a dielectric layer is characterized by unique reflective properties. It can have a noticeable impact on polarization of the p-polarized wave’s incident upon the layer. Dielectric layers provided with uniaxial metasurfaces can be used for creating optical and nanoelectronic devices of new types.","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":"67141719","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. Stanislavsky, I. Bubnov, S. Yerin, A. Zalizovski, V. Lisachenko
Subject and Purpose. Studying the time variations shown by the critical frequencies of the ionospheric F2 layer through comparative analysis of ionosonde data and observations of type III solar radio bursts. Methods and Methodology. In this work, two independent methods have been used for identifying critical frequencies in the ionosphere, namely that of vertical sounding and observations of type III solar radio bursts near their cut-off frequency in the ionosphere. One of the ionosondes used for vertical sounding was located near Zmiiv (Kharkiv Region), rather close to the UTR-2 radio astronomy observatory where the solar bursts were observed. The radiation from such bursts represented probe signals for transmissive sounding. The solar radiation was received with an element of a low-frequency (1 to 40 MHz) antenna array. Results. On May 22, 2021 variations in the critical frequency f0F2 of the ionospheric F2-layer were followed between 07:00 and 17:00 UT. The value reached a maximum of 5.9 MHz at 07:45 to 08:00 UT and then decreased smoothlyto 4.9 MHz, stayіng there from 15:30 till 16:45 UT. At that time, a storm of type III solar bursts was recorded with the antenna for radio observations at 1…40 MHz, revealing a cut-off effect for the bursts. As has been found,their cut-off frequency can be used for estimating the critical frequency f0F2 in the ionosphere. Conclusions. The comparative analysis of solar burst observations and frequency-and-time measurements with an ionosonde has shown possibilities for evaluating the critical frequency f0F2 in the ionosphere from the data on the cut-off frequency for solar radio-frequ
{"title":"THE CRITICAL FREQUENCY OF THE IONOSPHERIC F2-LAYER AS OBTAINED FROM IONOSONDE DATA AND OBSERVATIONS OF SOLAR RADIO BURSTS","authors":"L. Stanislavsky, I. Bubnov, S. Yerin, A. Zalizovski, V. Lisachenko","doi":"10.15407/rpra27.03.203","DOIUrl":"https://doi.org/10.15407/rpra27.03.203","url":null,"abstract":"Subject and Purpose. Studying the time variations shown by the critical frequencies of the ionospheric F2 layer through comparative analysis of ionosonde data and observations of type III solar radio bursts. Methods and Methodology. In this work, two independent methods have been used for identifying critical frequencies in the ionosphere, namely that of vertical sounding and observations of type III solar radio bursts near their cut-off frequency in the ionosphere. One of the ionosondes used for vertical sounding was located near Zmiiv (Kharkiv Region), rather close to the UTR-2 radio astronomy observatory where the solar bursts were observed. The radiation from such bursts represented probe signals for transmissive sounding. The solar radiation was received with an element of a low-frequency (1 to 40 MHz) antenna array. Results. On May 22, 2021 variations in the critical frequency f0F2 of the ionospheric F2-layer were followed between 07:00 and 17:00 UT. The value reached a maximum of 5.9 MHz at 07:45 to 08:00 UT and then decreased smoothlyto 4.9 MHz, stayіng there from 15:30 till 16:45 UT. At that time, a storm of type III solar bursts was recorded with the antenna for radio observations at 1…40 MHz, revealing a cut-off effect for the bursts. As has been found,their cut-off frequency can be used for estimating the critical frequency f0F2 in the ionosphere. Conclusions. The comparative analysis of solar burst observations and frequency-and-time measurements with an ionosonde has shown possibilities for evaluating the critical frequency f0F2 in the ionosphere from the data on the cut-off frequency for solar radio-frequ","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":"67141848","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}
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