This paper presents wideband indoor channel measurements in three of the millimeter wave (mmWave) bands for the fifth generation (5G) and beyond 5G (B5G) wireless systems. Measurements were conducted at the Ka-band (36-41 GHz) and V-band (50-75 GHz) in office and factory/industrial environments, using Durham University's custom-designed channel sounder. Recently, several channel measurements at different mmWave bands have been reported in various indoor environments. However, few studies have explored the impact of the processing bandwidth (BW) on the estimated channel parameters. Therefore, the aim of this paper is to investigate the effects of the analysis BW on different propagation channel characteristics, such as power delay profile, root mean square delay spread, Rician K-factor, coherence BW (Bc), and path loss. These wideband channel parameters are measured and estimated with a BW of 0.5, 1, 1.5, and 2 GHz. The results are presented for both line-of-sight and non-line-of-sight scenarios.
{"title":"Effects of bandwidth on millimeter wave channel characteristics and modeling analysis in indoor scenarios","authors":"Amar Al-Jzari;Sana Salous","doi":"10.1029/2025RS008261","DOIUrl":"https://doi.org/10.1029/2025RS008261","url":null,"abstract":"This paper presents wideband indoor channel measurements in three of the millimeter wave (mmWave) bands for the fifth generation (5G) and beyond 5G (B5G) wireless systems. Measurements were conducted at the Ka-band (36-41 GHz) and V-band (50-75 GHz) in office and factory/industrial environments, using Durham University's custom-designed channel sounder. Recently, several channel measurements at different mmWave bands have been reported in various indoor environments. However, few studies have explored the impact of the processing bandwidth (BW) on the estimated channel parameters. Therefore, the aim of this paper is to investigate the effects of the analysis BW on different propagation channel characteristics, such as power delay profile, root mean square delay spread, Rician K-factor, coherence BW (B<inf>c</inf>), and path loss. These wideband channel parameters are measured and estimated with a BW of 0.5, 1, 1.5, and 2 GHz. The results are presented for both line-of-sight and non-line-of-sight scenarios.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-14"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442704","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}
Daniel Atnafu Chekole;Nigussie Mezgebe Giday;Samson Tilahun Moges
This study aims to improve the estimation of Total Electron Content (TEC), the F2 layer critical frequency (foF2), and its peak height (hmF2) over East Africa by applying the Unscented Kalman Filter (UKF) to assimilate GPS-derived TEC and foF2/hmF2 from COSMIC-2 into the Standard Plasmaspheric and Ionospheric Model (SPIM). Assimilation was conducted in two experiments: (a) GPS TEC data were assimilated into the background model during geomagnetic quiet periods (23-26 September 2012; 21-24 May 2015; and 27-30 December 2017) and disturbed periods (7-10 March 2012; 16-19 March 2015; and 6-9 September 2017); and (b) foF2 and hmF2 were assimilated during the disturbed period of 23-27 September 2019. Our results show that the assimilation enhances the SPIM model's estimation of ionospheric parameters. The assimilation demonstrates strong agreement with observations, with correlation coefficient (R) >0.90 compared to the background model (R = 0.79 at moiu station, 0.29°N, 35.29°E, and 0.82 at nege station, 5.33°N, 39.59°E). UKF significantly enhances GPS TEC assimilation, with a maximum percentage error reduction of 49.02% during quiet periods across all stations. During geomagnetic disturbances, TEC assimilation reduced percentage error by 40.0%-59.55% relative to SPIM. Assimilated foF2 and hmF2 values show improved agreement with COSMIC-2 measurements. The maximum RMSE improvement in foF2 was about 99.35% over moiu station, 0.29°N, 35.29°E, and the minimum was 67.56% over mal2 station, −2.99°N, 40.02°E. For hmF2, the highest RMSE improvement was 97.31% over adis station, 9.03°N, 38.77°E, and the lowest was 60.16% over armi station, 6.06°N, 37.56°E, compared to the background SPIM model during the study periods.
{"title":"Assimilation of GPS TEC and COSMIC foF2/ hmF2 into SPIM model using unscented Kalman filter techniques over the east African equatorial region","authors":"Daniel Atnafu Chekole;Nigussie Mezgebe Giday;Samson Tilahun Moges","doi":"10.1029/2023RS007919","DOIUrl":"https://doi.org/10.1029/2023RS007919","url":null,"abstract":"This study aims to improve the estimation of Total Electron Content (TEC), the F2 layer critical frequency (foF2), and its peak height (hmF2) over East Africa by applying the Unscented Kalman Filter (UKF) to assimilate GPS-derived TEC and foF2/hmF2 from COSMIC-2 into the Standard Plasmaspheric and Ionospheric Model (SPIM). Assimilation was conducted in two experiments: (a) GPS TEC data were assimilated into the background model during geomagnetic quiet periods (23-26 September 2012; 21-24 May 2015; and 27-30 December 2017) and disturbed periods (7-10 March 2012; 16-19 March 2015; and 6-9 September 2017); and (b) foF2 and hmF2 were assimilated during the disturbed period of 23-27 September 2019. Our results show that the assimilation enhances the SPIM model's estimation of ionospheric parameters. The assimilation demonstrates strong agreement with observations, with correlation coefficient (R) >0.90 compared to the background model (R = 0.79 at moiu station, 0.29°N, 35.29°E, and 0.82 at nege station, 5.33°N, 39.59°E). UKF significantly enhances GPS TEC assimilation, with a maximum percentage error reduction of 49.02% during quiet periods across all stations. During geomagnetic disturbances, TEC assimilation reduced percentage error by 40.0%-59.55% relative to SPIM. Assimilated foF2 and hmF2 values show improved agreement with COSMIC-2 measurements. The maximum RMSE improvement in foF2 was about 99.35% over moiu station, 0.29°N, 35.29°E, and the minimum was 67.56% over mal2 station, −2.99°N, 40.02°E. For hmF2, the highest RMSE improvement was 97.31% over adis station, 9.03°N, 38.77°E, and the lowest was 60.16% over armi station, 6.06°N, 37.56°E, compared to the background SPIM model during the study periods.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-22"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442761","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}
In light of the characteristics of traditional wireless power transmission (WPT) systems, which include large size, low efficiency, and complex processing, this paper proposes a novel electrically small, low-profile, and high-efficiency Huygens source rectenna that can be effectively applied to 915 MHz wireless power transmission systems. The receiving antenna utilizes near-field resonant parasitic elements and incorporates a design featuring a folded electric dipole and an “Ω”-shaped magnetic dipole to achieve antenna miniaturization, with an electrical size ka of 0.724, making it easy to fabricate and cost-effective. By closely integrating it with a rectifier designed for low load, it exhibits a significant capability for capturing electromagnetic waves. Simulation results indicate that the circuit achieves a maximum rectification efficiency of 70%. The experimental results and simulation show good consistency. At an input power of 19.5 dBm, it achieves over 60% RF-to-DC conversion efficiency, making it more suitable for applications in wireless Internet of Things systems.
{"title":"Design of an improved low-profile, electrically small rectenna for wireless energy transmission","authors":"Hongjie Chen;Yongxing Du;Ling Qin;Baoshan Li","doi":"10.1029/2024RS008129","DOIUrl":"https://doi.org/10.1029/2024RS008129","url":null,"abstract":"In light of the characteristics of traditional wireless power transmission (WPT) systems, which include large size, low efficiency, and complex processing, this paper proposes a novel electrically small, low-profile, and high-efficiency Huygens source rectenna that can be effectively applied to 915 MHz wireless power transmission systems. The receiving antenna utilizes near-field resonant parasitic elements and incorporates a design featuring a folded electric dipole and an “Ω”-shaped magnetic dipole to achieve antenna miniaturization, with an electrical size ka of 0.724, making it easy to fabricate and cost-effective. By closely integrating it with a rectifier designed for low load, it exhibits a significant capability for capturing electromagnetic waves. Simulation results indicate that the circuit achieves a maximum rectification efficiency of 70%. The experimental results and simulation show good consistency. At an input power of 19.5 dBm, it achieves over 60% RF-to-DC conversion efficiency, making it more suitable for applications in wireless Internet of Things systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-10"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442762","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}
Wireless networks in 5G and Beyond 5G (B5G) will be more dynamic and heterogeneous, necessitating the use of multi-strand wave shape. The biggest serious obstacle in such a large-scale system, exclusively in non-cooperative situations, is determining the modulation type to recognize the precise encoding type employed by the broadcaster at the current moment in order to successfully decode the information. Typical modulation classification requires expert signal processing algorithms that perform noise reduction and estimation of signal parameters, namely, carrier frequency and signal power. Hence, this research introduces a revolutionary Automatic Modulation Classification (AMC) model that is built on reconfigurable “Convolutional BiLSTMDSnet (CbiLSTMDSnet).” The proposed reconfigured deep learning architecture is technologically advanced by merging the convolutional neural network, BiLSTM, and DSnet. A-MAX pooling layer is also included in the proposed model to boost classification accuracy. Furthermore, the Dimensionality reduction was also carried out with the help of a Restricted Boltzmann Machine to reduce the training time. Finally, a dropout layer and a Gaussian noise layer are added to the proposed neural network model to minimize the signal noises for effective modulation classification. The simulation results in evidence that the proposed AMC model outperforms existing classification models with improved accuracy of 99.8% in less time.
{"title":"CBiLSTMDSNet for automatic modulation classification in 5G and beyond","authors":"Aylapogu PramodKumar;Gurrala KiranKumar","doi":"10.1029/2024RS008131","DOIUrl":"https://doi.org/10.1029/2024RS008131","url":null,"abstract":"Wireless networks in 5G and Beyond 5G (B5G) will be more dynamic and heterogeneous, necessitating the use of multi-strand wave shape. The biggest serious obstacle in such a large-scale system, exclusively in non-cooperative situations, is determining the modulation type to recognize the precise encoding type employed by the broadcaster at the current moment in order to successfully decode the information. Typical modulation classification requires expert signal processing algorithms that perform noise reduction and estimation of signal parameters, namely, carrier frequency and signal power. Hence, this research introduces a revolutionary Automatic Modulation Classification (AMC) model that is built on reconfigurable “Convolutional BiLSTMDSnet (CbiLSTMDSnet).” The proposed reconfigured deep learning architecture is technologically advanced by merging the convolutional neural network, BiLSTM, and DSnet. A-MAX pooling layer is also included in the proposed model to boost classification accuracy. Furthermore, the Dimensionality reduction was also carried out with the help of a Restricted Boltzmann Machine to reduce the training time. Finally, a dropout layer and a Gaussian noise layer are added to the proposed neural network model to minimize the signal noises for effective modulation classification. The simulation results in evidence that the proposed AMC model outperforms existing classification models with improved accuracy of 99.8% in less time.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-19"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442747","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}
G. Álvarez-Botero;N. Duque-Madrid;H. Lobato-Morales;G. Méndez-Jerónimo;K. Hui;N. Tarabay;A. Pons-Abenza;I. Arregui;T. Lopetegi;M. A. G. Laso;C. Velez
This work presents an improved methodology for characterizing the effective permittivity (ε) and permeability (μ) of magnetodielectric (MD) composites, using Fe3O4 nanoparticles dispersed in a PDMS polymer matrix. The proposed approach integrates a planar split‐ring resonator sensor design and an artificial neural network model for parameter extraction, complemented by a line‐line deembedding methodology to eliminate parasitic effects from measurements. The experimental results are compared with predictions derived from the Maxwell‐Garnett and Polder‐Van Santen effective medium models, demonstrating a close agreement between theory and measurements. This study highlights the importance of accurate experimental procedures and advanced modeling techniques in understanding the electromagnetic behavior of MD composites and offers insights into their potential for developing next‐generation microwave components.
本文提出了一种改进的方法来表征磁介质（MD）复合材料的有效介电常数（ε）和磁导率（μ），使用分散在PDMS聚合物基体中的Fe3O4纳米颗粒。该方法集成了平面分裂环谐振器传感器设计和用于参数提取的人工神经网络模型，并辅以线-线去嵌入方法来消除测量中的寄生效应。实验结果与Maxwell - Garnett和Polder - Van Santen有效介质模型的预测结果进行了比较，证明了理论与测量之间的密切一致。这项研究强调了准确的实验程序和先进的建模技术在理解MD复合材料电磁行为方面的重要性，并为开发下一代微波元件提供了潜在的见解。
{"title":"Enhancing magneto-dielectric material characterization by integrating SRR sensor, de-embedding procedure, and artificial neural network modeling","authors":"G. Álvarez-Botero;N. Duque-Madrid;H. Lobato-Morales;G. Méndez-Jerónimo;K. Hui;N. Tarabay;A. Pons-Abenza;I. Arregui;T. Lopetegi;M. A. G. Laso;C. Velez","doi":"10.1029/2024RS008214","DOIUrl":"https://doi.org/10.1029/2024RS008214","url":null,"abstract":"This work presents an improved methodology for characterizing the effective permittivity (ε) and permeability (μ) of magnetodielectric (MD) composites, using Fe<inf>3</inf>O<inf>4</inf> nanoparticles dispersed in a PDMS polymer matrix. The proposed approach integrates a planar split‐ring resonator sensor design and an artificial neural network model for parameter extraction, complemented by a line‐line deembedding methodology to eliminate parasitic effects from measurements. The experimental results are compared with predictions derived from the Maxwell‐Garnett and Polder‐Van Santen effective medium models, demonstrating a close agreement between theory and measurements. This study highlights the importance of accurate experimental procedures and advanced modeling techniques in understanding the electromagnetic behavior of MD composites and offers insights into their potential for developing next‐generation microwave components.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-11"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442705","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 availability and integrity of Global Navigation Satellite Systems (GNSS) signals in low-latitude areas are seriously threatened by ionospheric irregularities which lead to amplitude scintillation. To better understand the low-latitude ionospheric impact on GNSS signal this study examines the relation between severe spatial ionospheric gradients, amplitude scintillation (quantified by the S4 index), and the fading coefficients of the α-μ model. Severe ionospheric gradients are typically observed in association with S4 greater than 0.6. These values of S4, however, are not sufficient to be associated to the occurrence of severe gradients. For GNSS-based systems, severe gradients create vulnerability scenarios by inducing integrity problems. The results in this work indicate that, given a fixed S4, the values of the fading coefficient a increase with gradient severity, suggesting a greater likelihood of deep signal fading. This correspondence is important because under larger S4 and α, the average time between cycle slips in the receiver is expected to decrease significantly, compromising the signal availability. The results also suggest that, to improve GNSS resilience, an integrated evaluation of S4, α, and ionospheric gradients must be considered in the development of more effective mitigation measures. For safety-critical GNSS applications, future studies should concentrate on improving these statistical models and incorporating them into operational monitoring frameworks.
{"title":"Joint analysis of spatial ionospheric gradients and scintillation fading coefficients","authors":"Renan Ruan Ferraz Sarmento;Lucas Gaudencio Vivacqua;Leonardo Marini-Pereira;Jonas Sousasantos;Alison Moraes","doi":"10.1029/2025RS008224","DOIUrl":"https://doi.org/10.1029/2025RS008224","url":null,"abstract":"The availability and integrity of Global Navigation Satellite Systems (GNSS) signals in low-latitude areas are seriously threatened by ionospheric irregularities which lead to amplitude scintillation. To better understand the low-latitude ionospheric impact on GNSS signal this study examines the relation between severe spatial ionospheric gradients, amplitude scintillation (quantified by the S<inf>4</inf> index), and the fading coefficients of the α-μ model. Severe ionospheric gradients are typically observed in association with S<inf>4</inf> greater than 0.6. These values of S<inf>4</inf>, however, are not sufficient to be associated to the occurrence of severe gradients. For GNSS-based systems, severe gradients create vulnerability scenarios by inducing integrity problems. The results in this work indicate that, given a fixed S<inf>4</inf>, the values of the fading coefficient a increase with gradient severity, suggesting a greater likelihood of deep signal fading. This correspondence is important because under larger S<inf>4</inf> and α, the average time between cycle slips in the receiver is expected to decrease significantly, compromising the signal availability. The results also suggest that, to improve GNSS resilience, an integrated evaluation of S<inf>4</inf>, α, and ionospheric gradients must be considered in the development of more effective mitigation measures. For safety-critical GNSS applications, future studies should concentrate on improving these statistical models and incorporating them into operational monitoring frameworks.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-17"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442710","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 aerospace industry has experienced remarkable advances through the adoption of composite materials and 3D technologies due to their optimal strength-to-weight ratio. However, the extreme temperature gradients in the space environment present considerable challenges for the stability and performance of these materials. This paper presents the design and proof-of-concept validation of a non-resonant electromagnetic characterization system to evaluate relative permittivity in dielectric materials under varying thermal conditions. The system utilizes dual-line microstrip technology, employing a phase extraction method to achieve precise measurements of effective permittivity. Both the dielectric loss tangent and the real part of the relative permittivity are analyzed for composite materials, including FR-4, ROGERS 4350B, and CuClad-250. These materials are tested over a wide frequency range (500 MHz-20 GHz) and under temperature conditions spanning — 55°C to 80°C. The study incorporates a validation phase conducted at room temperature, that includes both electromagnetic simulations and measurements, followed by measurements in a thermal chamber to evaluate material performance under varying thermal conditions. Although this study represents an initial prototype phase with planned improvements, the system shows consistency and reliability in measurements, highlighting the significant variation of permittivity with temperature.
{"title":"Design of an electromagnetic characterization system for materials at low and high temperature","authors":"Borja Plaza Gallardo;Alicia Auñón Marugán;Pablo Zamorano Fernández;Aymar Cublier Martínez;David Ramos Somolinos;David Poyatos Martínez","doi":"10.1029/2024RS008203","DOIUrl":"https://doi.org/10.1029/2024RS008203","url":null,"abstract":"The aerospace industry has experienced remarkable advances through the adoption of composite materials and 3D technologies due to their optimal strength-to-weight ratio. However, the extreme temperature gradients in the space environment present considerable challenges for the stability and performance of these materials. This paper presents the design and proof-of-concept validation of a non-resonant electromagnetic characterization system to evaluate relative permittivity in dielectric materials under varying thermal conditions. The system utilizes dual-line microstrip technology, employing a phase extraction method to achieve precise measurements of effective permittivity. Both the dielectric loss tangent and the real part of the relative permittivity are analyzed for composite materials, including FR-4, ROGERS 4350B, and CuClad-250. These materials are tested over a wide frequency range (500 MHz-20 GHz) and under temperature conditions spanning — 55°C to 80°C. The study incorporates a validation phase conducted at room temperature, that includes both electromagnetic simulations and measurements, followed by measurements in a thermal chamber to evaluate material performance under varying thermal conditions. Although this study represents an initial prototype phase with planned improvements, the system shows consistency and reliability in measurements, highlighting the significant variation of permittivity with temperature.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 10","pages":"1-20"},"PeriodicalIF":1.5,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145442748","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 study is based on the 68.5 kHz signal transmitted by China's low-frequency time code time service system (BPC) and systematically researches the effects of medium to large solar flares (M/X-class) on low-frequency time code signals. By analyzing the field strength and timing deviation data of the BPC signal during 20 typical flare events, the study reveals the variation patterns of low-frequency time code signals under disturbances from medium to large solar flares. Case analyses indicate that, during such flares, the BPC signal intensity exhibits two response patterns: a single-valley structure and a double-valley structure. The BPC signal response is divided into two stages—a rapid change phase and a gradual change phase—which show a strong linear relationship with the development of the solar flare. Meanwhile, the BPC timing deviation displays a bipolar pulse characteristic, and after the flare, the instability in signal performance is closely associated with the double-valley response in field strength. These phenomena suggest that the changes in the BPC time code signal are closely related to the effects of ionospheric disturbances during solar flares on the superposition characteristics of the BPC ground-wave and sky-wave signals. This first systematic investigation analyzes low-frequency time-code signal variation during medium-to-large solar flares, revealing their response characteristics. It provides significant insights into the low-frequency time-code signal propagation-solar activity association and lays a solid theoretical foundation for improving time-service stability and reliability.
{"title":"Study on the variation of low-frequency time code signals during medium to large solar flare events","authors":"Zhen Qi;Xiaoqian Ren;Qiang Liu;Fan Zhao;Luxi Huang;Yingming Chen;Xin Wang;Langlang Cheng;Yuping Gao;Ping Feng","doi":"10.1029/2024RS008186","DOIUrl":"https://doi.org/10.1029/2024RS008186","url":null,"abstract":"This study is based on the 68.5 kHz signal transmitted by China's low-frequency time code time service system (BPC) and systematically researches the effects of medium to large solar flares (M/X-class) on low-frequency time code signals. By analyzing the field strength and timing deviation data of the BPC signal during 20 typical flare events, the study reveals the variation patterns of low-frequency time code signals under disturbances from medium to large solar flares. Case analyses indicate that, during such flares, the BPC signal intensity exhibits two response patterns: a single-valley structure and a double-valley structure. The BPC signal response is divided into two stages—a rapid change phase and a gradual change phase—which show a strong linear relationship with the development of the solar flare. Meanwhile, the BPC timing deviation displays a bipolar pulse characteristic, and after the flare, the instability in signal performance is closely associated with the double-valley response in field strength. These phenomena suggest that the changes in the BPC time code signal are closely related to the effects of ionospheric disturbances during solar flares on the superposition characteristics of the BPC ground-wave and sky-wave signals. This first systematic investigation analyzes low-frequency time-code signal variation during medium-to-large solar flares, revealing their response characteristics. It provides significant insights into the low-frequency time-code signal propagation-solar activity association and lays a solid theoretical foundation for improving time-service stability and reliability.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 9","pages":"1-17"},"PeriodicalIF":1.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145196046","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}
H. T. Chou;C. Y. Chang;C. Y. Chou;S. Kawdungta;D. Torrungrueng
Many radiofrequency (RF) applications, including antenna-on-display and electromagnetic interference shielding, use thin meshed wires to form metal surfaces and ground planes, respectively, with good optical transparency. The characteristics of metal meshed-wire architectures are thus investigated in this paper to interpret their scattering behaviors, which allows the metal meshes to be properly applied to compose antenna radiators or shielding under a good light transparency consideration. They are resembled by an equivalent homogeneous dielectric substrate to simplify numerical simulation complexity. The equivalent conducting and dielectric properties of substrates are extracted from the propagating modes of the Floquet theorem. The equivalent conductivity and dielectric constant allow one to define a characteristic impedance to compute the reflection and transmission coefficients and therefore estimate the power efficiency for practical applications. Validations by numerical full-wave simulations using HFSS software at 28 GHz are shown to demonstrate their characteristics.
{"title":"Examinations of metal meshing surfaces to retain good optical transparency in different electromagnetic shielding effectiveness","authors":"H. T. Chou;C. Y. Chang;C. Y. Chou;S. Kawdungta;D. Torrungrueng","doi":"10.1029/2024RS008108","DOIUrl":"https://doi.org/10.1029/2024RS008108","url":null,"abstract":"Many radiofrequency (RF) applications, including antenna-on-display and electromagnetic interference shielding, use thin meshed wires to form metal surfaces and ground planes, respectively, with good optical transparency. The characteristics of metal meshed-wire architectures are thus investigated in this paper to interpret their scattering behaviors, which allows the metal meshes to be properly applied to compose antenna radiators or shielding under a good light transparency consideration. They are resembled by an equivalent homogeneous dielectric substrate to simplify numerical simulation complexity. The equivalent conducting and dielectric properties of substrates are extracted from the propagating modes of the Floquet theorem. The equivalent conductivity and dielectric constant allow one to define a characteristic impedance to compute the reflection and transmission coefficients and therefore estimate the power efficiency for practical applications. Validations by numerical full-wave simulations using HFSS software at 28 GHz are shown to demonstrate their characteristics.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 9","pages":"1-15"},"PeriodicalIF":1.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145196045","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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