Inversion of precise true height electron density profile from the measured virtual heights by the Ionosonde is a quite challenging and ill-posed problem. In this paper, we present a new method to compute the true height profiles from ionograms that relies on computing the propagation path of radio waves with time. This method does not use predefined polynomial functions to fit the vertical electron density distribution; hence, it is free from fitting errors. Instead, this method implements iterative corrections in the electron density gradient between the successive points and progressively reconstructs the true height profile. This Iterative Gradient Correction (IGC) method assures minimizing the error to below a tolerance limit at all sampled points on the ionogram. The true height profiles derived from this method exhibit better accuracy than those derived from the widely used POLynomial ANalysis, particularly, at cusp and F2-peak regions. Further, the IGC method gives the best results at higher sampling resolutions of ionograms and is less sensitive to scaling errors.
{"title":"Iterative gradient correction (IGC) method for true height analysis of ionograms","authors":"M. Ankita;S. Tulasi Ram","doi":"10.1029/2023RS007808","DOIUrl":"10.1029/2023RS007808","url":null,"abstract":"Inversion of precise true height electron density profile from the measured virtual heights by the Ionosonde is a quite challenging and ill-posed problem. In this paper, we present a new method to compute the true height profiles from ionograms that relies on computing the propagation path of radio waves with time. This method does not use predefined polynomial functions to fit the vertical electron density distribution; hence, it is free from fitting errors. Instead, this method implements iterative corrections in the electron density gradient between the successive points and progressively reconstructs the true height profile. This Iterative Gradient Correction (IGC) method assures minimizing the error to below a tolerance limit at all sampled points on the ionogram. The true height profiles derived from this method exhibit better accuracy than those derived from the widely used POLynomial ANalysis, particularly, at cusp and F2-peak regions. Further, the IGC method gives the best results at higher sampling resolutions of ionograms and is less sensitive to scaling errors.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 11","pages":"1-13"},"PeriodicalIF":1.6,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135454978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This research proposes and investigates an elliptical waveguide filled with chiro plasma as its core and magnetized plasma as its clad region. The clad region is in the constant infinite magnetic field, and its direction is the same as the wave propagation in the chiro plasma elliptical waveguide. The electromagnetic wave propagation in the considered waveguide is studied. The expressions for electromagnetic field components in the chiro plasma core and magnetized plasma cladding are derived. The dispersion relations for the hybrid modes are calculated considering appropriate boundary conditions at the chiro plasma and magnetized plasma interface. The behavior of the energy flux and the dispersion curves are numerically and graphically studied. It is seen that the magnitude of the power density decreases with the increase of the cyclotron frequency and it increases with the increase of the plasma frequency and supports power flow in the backward direction for the considered mode. Furthermore, it is shown higher values of the chirality parameter cause the magnitude of the power flux to increase in the backward direction.
{"title":"Analysis and application of the electromagnetic wave propagation, fields, and dispersion relation in an elliptical chiro plasma waveguide immersed in magnetized plasma","authors":"N. Gholamshahi;A. Abdoli-Arani","doi":"10.1029/2023RS007815","DOIUrl":"10.1029/2023RS007815","url":null,"abstract":"This research proposes and investigates an elliptical waveguide filled with chiro plasma as its core and magnetized plasma as its clad region. The clad region is in the constant infinite magnetic field, and its direction is the same as the wave propagation in the chiro plasma elliptical waveguide. The electromagnetic wave propagation in the considered waveguide is studied. The expressions for electromagnetic field components in the chiro plasma core and magnetized plasma cladding are derived. The dispersion relations for the hybrid modes are calculated considering appropriate boundary conditions at the chiro plasma and magnetized plasma interface. The behavior of the energy flux and the dispersion curves are numerically and graphically studied. It is seen that the magnitude of the power density decreases with the increase of the cyclotron frequency and it increases with the increase of the plasma frequency and supports power flow in the backward direction for the considered mode. Furthermore, it is shown higher values of the chirality parameter cause the magnitude of the power flux to increase in the backward direction.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 11","pages":"1-12"},"PeriodicalIF":1.6,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134907384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. S. da Silva;A. L. P. S. Campos;M. E. T. Sousa;M. W. B. Silva;H. D. Andrade
A specific class of frequency selective surface (FSS) is the complementary frequency selective surface (CFSS) that has interesting characteristics such as high angular stability, multiple transmission and/ or reflection bands, and the possibility of miniaturization. The analysis and design of this sort of structure are commonly performed using commercial software, which demands a high computational effort, impacting a longer optimization time. The equivalent circuit model combined with a cascading technique emerges as an alternative method to the use of these softwares, in the optimization of the physical dimensions of these structures, as they model the behavior of a CFSS with low computational effort and optimization time, in addition to being able to be implemented in various programming languages. Thus, this work proposes a CFSS analysis technique that combines the equivalent circuit method with the ABCD matrix. To the best of our knowledge, this is the first reported research on approximate techniques for CFSS analysis. The chosen geometry was the circular ring, due to high angular stability and polarization independence. The modeling of the equivalent circuit for patch and aperture geometries is presented. Some structures are simulated, and the results are compared with results obtained with the HFSS software. Finally, two prototypes are built to validate the analyses performed.
{"title":"Proposal of technique for analysis of complementary frequency selective surfaces","authors":"B. S. da Silva;A. L. P. S. Campos;M. E. T. Sousa;M. W. B. Silva;H. D. Andrade","doi":"10.1029/2022RS007621","DOIUrl":"https://doi.org/10.1029/2022RS007621","url":null,"abstract":"A specific class of frequency selective surface (FSS) is the complementary frequency selective surface (CFSS) that has interesting characteristics such as high angular stability, multiple transmission and/ or reflection bands, and the possibility of miniaturization. The analysis and design of this sort of structure are commonly performed using commercial software, which demands a high computational effort, impacting a longer optimization time. The equivalent circuit model combined with a cascading technique emerges as an alternative method to the use of these softwares, in the optimization of the physical dimensions of these structures, as they model the behavior of a CFSS with low computational effort and optimization time, in addition to being able to be implemented in various programming languages. Thus, this work proposes a CFSS analysis technique that combines the equivalent circuit method with the ABCD matrix. To the best of our knowledge, this is the first reported research on approximate techniques for CFSS analysis. The chosen geometry was the circular ring, due to high angular stability and polarization independence. The modeling of the equivalent circuit for patch and aperture geometries is presented. Some structures are simulated, and the results are compared with results obtained with the HFSS software. Finally, two prototypes are built to validate the analyses performed.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 10","pages":"1-8"},"PeriodicalIF":1.6,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71903264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The quantitative relationship between the channel-base current and the associated low-frequency magnetic field (B-field) during the early stage of rocket-triggered lightning was examined based on field experiments and numerical simulation. There is a good correlation between the current pulse and the corresponding B-field pulse in terms of amplitude and duration. In specific, the duration of current pulse is approximately proportional to that of the corresponding B-field pulse for precursors and initial upward leaders; as for the pulse amplitude, the linear correlation is more apparent for the initial upward leaders when compared to the precursors, with the ratio of B-field pulse and current pulse between 1.7 and 2.0, which is always greater than that (0.97–1.32) for the precursors. A response function is established to show the quantitative relationship in the time domain between the current pulse and the associated B-field pulse, which is considered as the convolution of the current pulse and the response function. Meanwhile, the current waveform can be obtained if the measured B-field pulse is de-convolved with the response function. The simulation results are in good agreement with the measurement, which proves that our approach is accurate and efficient to quantify the relationship between the current and the B-field pulse of the initial leader discharges.
{"title":"Quantitative relationship between current pulses and associated low-frequency magnetic fields during initial stage of rocket-triggered lightning","authors":"Xiao Li;Gaopeng Lu;Ziyi Wang;Rubin Jiang;Yanfeng Fan;Yucheng Zi;Feifan Liu;Kainat Qamar;Alice Nambalirwa;Tao Shi;Baoyou Zhu","doi":"10.1029/2022RS007647","DOIUrl":"https://doi.org/10.1029/2022RS007647","url":null,"abstract":"The quantitative relationship between the channel-base current and the associated low-frequency magnetic field (B-field) during the early stage of rocket-triggered lightning was examined based on field experiments and numerical simulation. There is a good correlation between the current pulse and the corresponding B-field pulse in terms of amplitude and duration. In specific, the duration of current pulse is approximately proportional to that of the corresponding B-field pulse for precursors and initial upward leaders; as for the pulse amplitude, the linear correlation is more apparent for the initial upward leaders when compared to the precursors, with the ratio of B-field pulse and current pulse between 1.7 and 2.0, which is always greater than that (0.97–1.32) for the precursors. A response function is established to show the quantitative relationship in the time domain between the current pulse and the associated B-field pulse, which is considered as the convolution of the current pulse and the response function. Meanwhile, the current waveform can be obtained if the measured B-field pulse is de-convolved with the response function. The simulation results are in good agreement with the measurement, which proves that our approach is accurate and efficient to quantify the relationship between the current and the B-field pulse of the initial leader discharges.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 10","pages":"1-12"},"PeriodicalIF":1.6,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71903261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transionospheric satellite signals are exposed to perturbation, caused by irregularities generated in the ionosphere. However, the characteristics of the satellite motion can have an additional impact on signal perturbation, in addition to the effects of irregularity structures, that drift from west to east during geomagnetic quiet conditions. This paper reports the effect of Global Positioning System satellite geometry, on tracking loop performance of ground-based receivers, during occurrence of ionospheric scintillations. Observations are made from station Calcutta (22.58°N, 88.38°E geographic; magnetic dip 34.54°), located near the northern crest of Equatorial Ionization Anomaly, during three different solar activity periods (March 2014, March 2015, and March 2022). Efforts have been made to study the correlation of east-west component of satellite velocity at Ionospheric Pierce Point (IPP) with duration of loss-of-lock and rate of signal fading (<−10 dB), from ground scintillation pattern observations. Results of this study show 75%–78% correlation between duration of loss-of-lock and eastward component of satellite velocity, for all three period of observation. Subsequently, shorter duration of loss-of-lock has been observed corresponding to satellite velocity being westward. Signal fading rate is found to decrease with increasing satellite velocity, having median value of the fading rate cumulative distribution percentage, corresponding to satellite velocity of 16.69, 31.76, and 19.14 m/s respectively during March 2014, March 2015, and March 2022. Results of this study also indicate direction and component of satellite velocity at IPP to be a dominant cause of signal outage, even during periods of weak to moderate scintillations.
{"title":"Effects of the relative dynamics of ionospheric irregularities and GPS satellites on receiver tracking loop performance","authors":"Trisani Biswas;Ashik Paul","doi":"10.1029/2023RS007669","DOIUrl":"https://doi.org/10.1029/2023RS007669","url":null,"abstract":"Transionospheric satellite signals are exposed to perturbation, caused by irregularities generated in the ionosphere. However, the characteristics of the satellite motion can have an additional impact on signal perturbation, in addition to the effects of irregularity structures, that drift from west to east during geomagnetic quiet conditions. This paper reports the effect of Global Positioning System satellite geometry, on tracking loop performance of ground-based receivers, during occurrence of ionospheric scintillations. Observations are made from station Calcutta (22.58°N, 88.38°E geographic; magnetic dip 34.54°), located near the northern crest of Equatorial Ionization Anomaly, during three different solar activity periods (March 2014, March 2015, and March 2022). Efforts have been made to study the correlation of east-west component of satellite velocity at Ionospheric Pierce Point (IPP) with duration of loss-of-lock and rate of signal fading (<−10 dB), from ground scintillation pattern observations. Results of this study show 75%–78% correlation between duration of loss-of-lock and eastward component of satellite velocity, for all three period of observation. Subsequently, shorter duration of loss-of-lock has been observed corresponding to satellite velocity being westward. Signal fading rate is found to decrease with increasing satellite velocity, having median value of the fading rate cumulative distribution percentage, corresponding to satellite velocity of 16.69, 31.76, and 19.14 m/s respectively during March 2014, March 2015, and March 2022. Results of this study also indicate direction and component of satellite velocity at IPP to be a dominant cause of signal outage, even during periods of weak to moderate scintillations.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 10","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71903262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Iftikhar ud Din;Mohammad Alibakhshikenari;Bal S. Virdee;Sadiq Ullah;Shakir Ullah;Muhammad Rizwan Akram;Syed Mansoor Ali;Patrizia Livreri;Ernesto Limiti
This paper presents a high-performance multiple input and multiple output (MIMO) antenna comprising 2 × 2 configuration of radiating elements that is designed for sub-6 GHz applications. The proposed MIMO antenna employs four identical radiating elements. High isolation between the radiating elements and therefore reduced mutual coupling is achieved by spatially arranging the radiating elements in an orthogonal configuration. Also, a novel frequency selective surface (FSS) was employed to increase the gain of the MIMO antenna over a wide bandwidth from 3 to 6 GHz. This was achieved by locating the FSS above the antenna at a certain height. The FSS essentially enhanced the antenna's directivity, reduced back lobe radiation and mutual coupling. The antenna was fabricated on a standard Rogers RT Duroid 5880 dielectric substrate with a 0.8 mm thickness. The overall dimension of the MIMO antenna is 50 × 50 × 12.5 mm 3 and it operates from 3.8 to 6 GHz, which corresponds to a fractional bandwidth of 41%. The proposed MIMO antenna has a measured peak gain of 4.8 dBi and inter radiation element isolation >20 dB. Its envelope correlation coefficient is <0.1>9.9 (dB). These characteristics make the proposed MIMO antenna system suitable for 5G communication systems.
{"title":"High performance antenna system in MIMO configuration for 5G wireless communications over sub-6 GHz spectrum","authors":"Iftikhar ud Din;Mohammad Alibakhshikenari;Bal S. Virdee;Sadiq Ullah;Shakir Ullah;Muhammad Rizwan Akram;Syed Mansoor Ali;Patrizia Livreri;Ernesto Limiti","doi":"10.1029/2023RS007726","DOIUrl":"https://doi.org/10.1029/2023RS007726","url":null,"abstract":"This paper presents a high-performance multiple input and multiple output (MIMO) antenna comprising 2 × 2 configuration of radiating elements that is designed for sub-6 GHz applications. The proposed MIMO antenna employs four identical radiating elements. High isolation between the radiating elements and therefore reduced mutual coupling is achieved by spatially arranging the radiating elements in an orthogonal configuration. Also, a novel frequency selective surface (FSS) was employed to increase the gain of the MIMO antenna over a wide bandwidth from 3 to 6 GHz. This was achieved by locating the FSS above the antenna at a certain height. The FSS essentially enhanced the antenna's directivity, reduced back lobe radiation and mutual coupling. The antenna was fabricated on a standard Rogers RT Duroid 5880 dielectric substrate with a 0.8 mm thickness. The overall dimension of the MIMO antenna is 50 × 50 × 12.5 mm\u0000<sup>3</sup>\u0000 and it operates from 3.8 to 6 GHz, which corresponds to a fractional bandwidth of 41%. The proposed MIMO antenna has a measured peak gain of 4.8 dBi and inter radiation element isolation >20 dB. Its envelope correlation coefficient is <0.1>9.9 (dB). These characteristics make the proposed MIMO antenna system suitable for 5G communication systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 10","pages":"1-22"},"PeriodicalIF":1.6,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71903263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giada M. Battaglia;Tommaso Isernia;Roberta Palmeri;Andrea F. Morabito
We propose a new approach to the mask-constrained power synthesis of reconfigurable circular-ring array antennas for monopulse radar applications. By resorting to Orbital Angular Momentum vortex beams, and without increasing either the complexity of the beam forming network or the signal processing times with respect to the state-of-art solutions, the proposed method allows improving the precision pointing with respect to usual techniques. The overall synthesis is cast as a Convex Programming optimization problem aimed at reducing as much as possible the number of control points of the array, and it is tested in relevant application scenarios.
{"title":"Four-beams-reconfigurable circular-ring array antennas for monopulse radar applications","authors":"Giada M. Battaglia;Tommaso Isernia;Roberta Palmeri;Andrea F. Morabito","doi":"10.1029/2023RS007776","DOIUrl":"10.1029/2023RS007776","url":null,"abstract":"We propose a new approach to the mask-constrained power synthesis of reconfigurable circular-ring array antennas for monopulse radar applications. By resorting to Orbital Angular Momentum vortex beams, and without increasing either the complexity of the beam forming network or the signal processing times with respect to the state-of-art solutions, the proposed method allows improving the precision pointing with respect to usual techniques. The overall synthesis is cast as a Convex Programming optimization problem aimed at reducing as much as possible the number of control points of the array, and it is tested in relevant application scenarios.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"58 9","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41493092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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