State estimation techniques play an important role in predicting signal stability and estimating the primary variables in a system. State estimation using conventional methods predicts the state vectors with still random errors, such as those of the Wiener and Kalman, due to its parametric limitations in stationary and nonstationary environments. The Kalman filter is recognized as a linear-quadratic estimator. These measures, over a period of observation, include random noise, producing estimates of unknown variables that are more accurate than a single measurement. It generates the output of joint probability distribution function estimations over the variables for each time frame. This study proposes a Hybrid Kalman filter-based state estimation, applicable on a conditional of linear functions on a Gaussian random process and Gaussian random variables. The proposed Hybrid Kalman filter works to model the movement control differences of transmitted and received signals due to the time delay. This approach provides a realistic model to estimate the current state and produce updated state variables. A newly designed mobile station receiver was tested to receive transmitted signals from a 128-element array satellite antenna via an 8-element array antenna integrated with a Hybrid Kalman filter. This transceiver was validated at a frequency of 11 GHz, operating data rates of 1.28 Gbps for the bandwidth of 1.28 GHz to eliminate the multipath effects and reduce inter-symbol interference. The performance result of the simulation process shows the efficiency of the Hybrid Kalman filter when the 5G wireless network integrations are in a highly multipath environment.
{"title":"Mobile transceiver design with Hybrid Kalman filter for 5G wireless networks of satellite communications","authors":"Ravandran Muttiah","doi":"10.1029/2025RS008246","DOIUrl":"https://doi.org/10.1029/2025RS008246","url":null,"abstract":"State estimation techniques play an important role in predicting signal stability and estimating the primary variables in a system. State estimation using conventional methods predicts the state vectors with still random errors, such as those of the Wiener and Kalman, due to its parametric limitations in stationary and nonstationary environments. The Kalman filter is recognized as a linear-quadratic estimator. These measures, over a period of observation, include random noise, producing estimates of unknown variables that are more accurate than a single measurement. It generates the output of joint probability distribution function estimations over the variables for each time frame. This study proposes a Hybrid Kalman filter-based state estimation, applicable on a conditional of linear functions on a Gaussian random process and Gaussian random variables. The proposed Hybrid Kalman filter works to model the movement control differences of transmitted and received signals due to the time delay. This approach provides a realistic model to estimate the current state and produce updated state variables. A newly designed mobile station receiver was tested to receive transmitted signals from a 128-element array satellite antenna via an 8-element array antenna integrated with a Hybrid Kalman filter. This transceiver was validated at a frequency of 11 GHz, operating data rates of 1.28 Gbps for the bandwidth of 1.28 GHz to eliminate the multipath effects and reduce inter-symbol interference. The performance result of the simulation process shows the efficiency of the Hybrid Kalman filter when the 5G wireless network integrations are in a highly multipath environment.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-23"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646101","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}
Gabriel O. Jerez;Manuel Hernández-Pajares;Daniele B. M. Alves;João F. G. Monico
Global Navigation Satellite Systems radio occultation (RO) is a valuable and relevant source of information from the atmosphere. Many efforts have been made to provide methods of validation of RO profiles, however, no clear methodology for filtering the profiles from RO can be easily found. In this study, we present strategies to filter RO electron density profiles over a low latitude region. Different methods are applied considering minimum values, manual filtering, hmF2 range, and discrepancies with reference to the Chapman profile. The assessment is performed by means of ionosonde data for two years (2014–2015). The results show that assuming a minimum electron density limit slightly smaller than zero consistently with electron density estimation errors under very low actual values can provide significant improvements. In this study, the use of a —105 el/cm3 limit led to better rates of retained profiles (65% vs. 32%) and a reduction in foF2 root mean square (RMS) (12% vs. 7%) compared to the exclusion of all profiles with negative values. When considering only electron density values above 100 km in altitude, there is still a significant loss of about 20% in the number of profiles with the same reference values (84% vs. 63%), with a similar performance in thefoF2 RMS. The best performance is obtained with the strategies: hmF2 range of occurrence (200–450 km) and the outliers identification (5 standard deviations limit), leading to afoF2 RMS reduction of about 26% and 19%, and a hmF2 RMS reduction of 34% and 25%, respectively, while keeping 91% and 82% of the original profiles.
全球导航卫星系统的无线电掩星（RO）是一个有价值和相关的大气信息来源。许多努力已经提供了验证RO配置文件的方法，但是，没有明确的方法可以很容易地从RO中过滤配置文件。在这项研究中，我们提出了在低纬度地区过滤RO电子密度剖面的策略。考虑最小值、手动过滤、hmF2范围和参考查普曼剖面的差异，应用了不同的方法。评估是通过两年（2014-2015年）的电离探空仪数据进行的。结果表明，假设最小电子密度极限略小于零，与非常低的实际值下的电子密度估计误差一致，可以提供显着的改进。在这项研究中，与排除所有负值的剖面相比，使用-105 el/cm3的限制导致了更好的剖面保留率（65%对32%）和foF2均方根（RMS）降低（12%对7%）。当只考虑海拔100公里以上的电子密度值时，具有相同参考值的剖面数量仍然有大约20%的显着损失（84% vs. 63%），在fof2 RMS中具有相似的性能。hmF2发生范围（200-450 km）和异常值识别（5个标准差限）策略的效果最好，在保持原始剖面91%和82%的情况下，afoF2 RMS分别降低约26%和19%，hmF2 RMS分别降低34%和25%。
{"title":"Impact of filtering methods in the assessment of COSMIC electron density profiles over the Brazilian region: Excluding profiles with negative values is the best strategy?","authors":"Gabriel O. Jerez;Manuel Hernández-Pajares;Daniele B. M. Alves;João F. G. Monico","doi":"10.1029/2024RS008192","DOIUrl":"https://doi.org/10.1029/2024RS008192","url":null,"abstract":"Global Navigation Satellite Systems radio occultation (RO) is a valuable and relevant source of information from the atmosphere. Many efforts have been made to provide methods of validation of RO profiles, however, no clear methodology for filtering the profiles from RO can be easily found. In this study, we present strategies to filter RO electron density profiles over a low latitude region. Different methods are applied considering minimum values, manual filtering, hmF<inf>2</inf> range, and discrepancies with reference to the Chapman profile. The assessment is performed by means of ionosonde data for two years (2014–2015). The results show that assuming a minimum electron density limit slightly smaller than zero consistently with electron density estimation errors under very low actual values can provide significant improvements. In this study, the use of a —10<sup>5</sup> el/cm<sup>3</sup> limit led to better rates of retained profiles (65% vs. 32%) and a reduction in foF<inf>2</inf> root mean square (RMS) (12% vs. 7%) compared to the exclusion of all profiles with negative values. When considering only electron density values above 100 km in altitude, there is still a significant loss of about 20% in the number of profiles with the same reference values (84% vs. 63%), with a similar performance in thefoF<inf>2</inf> RMS. The best performance is obtained with the strategies: hmF<inf>2</inf> range of occurrence (200–450 km) and the outliers identification (5 standard deviations limit), leading to afoF<inf>2</inf> RMS reduction of about 26% and 19%, and a hmF<inf>2</inf> RMS reduction of 34% and 25%, respectively, while keeping 91% and 82% of the original profiles.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-13"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646104","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 focuses on developing an efficient, high-isolation Multi-Input Multi-Output (MIMO) antenna array for Mobile Satellite Services (MSS). A portion of the S-band (2-4 GHz) ranging from 2 to 2.2 GHz, known as Unified S-Band (USB), is utilized for MSS, particularly for Space-to-Earth communications. The ultimate objective of the proposed MIMO is to cover the USB spectrum and resonate at 2.2 GHz. As the first step of the design process, a meandered line (ML) monopole patch with good radiation characteristics in the desired frequency band is designed. Then, the mirror image of the proposed ML radiator is added to the design to form a two-element ML-MIMO array. A well-designed MIMO is highly beneficial for boosting the reliabilities, channel capacities, and frequency reuse in next-generation communication. But at the same time, it inherently increases the coupling effect between closely placed radiators, which may degrade the performance of the overall design. To overcome the coupling effect, a defected ground structure (DGS) is proposed in the partial ground plane of the ML-MIMO. The proposed DGS intends to reduce the coupling effects by perturbing the surface current distributions in the partial ground plane. Meanwhile, the DGS also enhances the compactness of the entire structure by boosting the gain and reducing the total weight. MIMO parameter metrics such as axial ratio below 3 dB, envelope correlation coefficient less than 0.0005, and a diversity gain close to 10 are also aimed by simultaneously reducing the mutual coupling below — 30 dB and return loss below — 25 dB for standard MIMO applications. The ML-MIMO is then fabricated on a FR4 substrate with a dimension of 40 mm by 48 mm, and measured. The simulated outcomes are found to be in close approximation with the measurement outcomes. A detailed comparison and trade-off analysis of the proposed design with respect to other contemporary research is also presented for further validation.
{"title":"Defected ground structure (DGS) based MIMO antenna array with decent isolation characteristics for satellite communications in unified S-band (USB)","authors":"Avishek Chakraborty;Ravi Shankar Saxena;Indrasen Singh;Jatinder Kaur;Ramneet Kaur;Rishiv Kalia;D. Durga Bhavani","doi":"10.1029/2025RS008379","DOIUrl":"https://doi.org/10.1029/2025RS008379","url":null,"abstract":"This research focuses on developing an efficient, high-isolation Multi-Input Multi-Output (MIMO) antenna array for Mobile Satellite Services (MSS). A portion of the S-band (2-4 GHz) ranging from 2 to 2.2 GHz, known as Unified S-Band (USB), is utilized for MSS, particularly for Space-to-Earth communications. The ultimate objective of the proposed MIMO is to cover the USB spectrum and resonate at 2.2 GHz. As the first step of the design process, a meandered line (ML) monopole patch with good radiation characteristics in the desired frequency band is designed. Then, the mirror image of the proposed ML radiator is added to the design to form a two-element ML-MIMO array. A well-designed MIMO is highly beneficial for boosting the reliabilities, channel capacities, and frequency reuse in next-generation communication. But at the same time, it inherently increases the coupling effect between closely placed radiators, which may degrade the performance of the overall design. To overcome the coupling effect, a defected ground structure (DGS) is proposed in the partial ground plane of the ML-MIMO. The proposed DGS intends to reduce the coupling effects by perturbing the surface current distributions in the partial ground plane. Meanwhile, the DGS also enhances the compactness of the entire structure by boosting the gain and reducing the total weight. MIMO parameter metrics such as axial ratio below 3 dB, envelope correlation coefficient less than 0.0005, and a diversity gain close to 10 are also aimed by simultaneously reducing the mutual coupling below — 30 dB and return loss below — 25 dB for standard MIMO applications. The ML-MIMO is then fabricated on a FR4 substrate with a dimension of 40 mm by 48 mm, and measured. The simulated outcomes are found to be in close approximation with the measurement outcomes. A detailed comparison and trade-off analysis of the proposed design with respect to other contemporary research is also presented for further validation.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-17"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646099","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}
A rigorous analysis of air-filled parallel-plate T-junctions is carried out using the method of Kobayashi Potential (KP). Compared to the previous reports on the topic, the inclusion of the corresponding edge conditions in the solution is assured. Thus, the uniqueness of the solution is guaranteed. A systematic procedure is presented to extract the scattering parameters and the corresponding results are compared with measured results. Additionally, possible choices of integration paths regarding the required spectral integrals are rigorously discussed and the corresponding closed-form solutions are provided using calculus of residues.
{"title":"Analysis of parallel-plate T-junctions using the method of Kobayashi potential","authors":"B. Honarbakhsh","doi":"10.1029/2025RS008429","DOIUrl":"https://doi.org/10.1029/2025RS008429","url":null,"abstract":"A rigorous analysis of air-filled parallel-plate T-junctions is carried out using the method of Kobayashi Potential (KP). Compared to the previous reports on the topic, the inclusion of the corresponding edge conditions in the solution is assured. Thus, the uniqueness of the solution is guaranteed. A systematic procedure is presented to extract the scattering parameters and the corresponding results are compared with measured results. Additionally, possible choices of integration paths regarding the required spectral integrals are rigorously discussed and the corresponding closed-form solutions are provided using calculus of residues.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-10"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646100","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}
W. Mary Dusabe;Jared O. H. Ndeda;O. J. Olwendo;A. J. Kiroe
This study presents the first analysis of ionospheric scintillation impacts on Global Positioning System (GPS) accuracy in Kenya across different solar cycle phases. Data from the University of Nairobi (1.3°S, 36.8°E; dip — 22.9°) was analyzed for geomagnetically quiet and selected disturbed periods between 2009 and 2012. The focus was on the nighttime period (1800-0600 LT), when low-latitude ionospheric plasma instabilities are most pronounced. These instabilities generate irregularities at various scales, which in turn increases the vulnerability of trans-ionospheric radio signals to degradation, by causing signal scintillation. Scintillation, measured by the amplitude scintillation index (S4), was classified as strong (S4 > 0.3), moderate (0.2 ≤ S4 ≤ 0.3), or weak (0.1 ≤ S4 ≤ 0.2). Strong scintillation, most frequent during equinoxes, corresponded to average positioning errors of about 4 m horizontally and 8 m vertically. Moderate scintillation produced average errors of approximately 2.5 m horizontally and 6 m vertically, while weak or non-scintillating periods still produced minimal average errors of about 1 m horizontal and 4 m vertical. The severity of positioning errors increased with solar activity, with a minimum in 2009 and a peak in 2012. Storm-time analysis indicated that storm intensity, timing, and associated electric fields, particularly prompt penetration (PPEFs) and disturbance dynamo (DDEFs), strongly influence the development or suppression of ionospheric irregularities. These findings underscore the vulnerability of GPS in equatorial regions during high solar activity. GPS users, especially in precision-demanding sectors such as agriculture, aviation, and surveying, should integrate enhanced ionospheric models and mitigation strategies to maintain accuracy and operational reliability.
{"title":"Investigation of ionospheric scintillation occurrence and the impact on GNSS positioning accuracy in Kenya","authors":"W. Mary Dusabe;Jared O. H. Ndeda;O. J. Olwendo;A. J. Kiroe","doi":"10.1029/2025RS008262","DOIUrl":"https://doi.org/10.1029/2025RS008262","url":null,"abstract":"This study presents the first analysis of ionospheric scintillation impacts on Global Positioning System (GPS) accuracy in Kenya across different solar cycle phases. Data from the University of Nairobi (1.3°S, 36.8°E; dip — 22.9°) was analyzed for geomagnetically quiet and selected disturbed periods between 2009 and 2012. The focus was on the nighttime period (1800-0600 LT), when low-latitude ionospheric plasma instabilities are most pronounced. These instabilities generate irregularities at various scales, which in turn increases the vulnerability of trans-ionospheric radio signals to degradation, by causing signal scintillation. Scintillation, measured by the amplitude scintillation index (S<inf>4</inf>), was classified as strong (S<inf>4</inf> > 0.3), moderate (0.2 ≤ S<inf>4</inf> ≤ 0.3), or weak (0.1 ≤ S<inf>4</inf> ≤ 0.2). Strong scintillation, most frequent during equinoxes, corresponded to average positioning errors of about 4 m horizontally and 8 m vertically. Moderate scintillation produced average errors of approximately 2.5 m horizontally and 6 m vertically, while weak or non-scintillating periods still produced minimal average errors of about 1 m horizontal and 4 m vertical. The severity of positioning errors increased with solar activity, with a minimum in 2009 and a peak in 2012. Storm-time analysis indicated that storm intensity, timing, and associated electric fields, particularly prompt penetration (PPEFs) and disturbance dynamo (DDEFs), strongly influence the development or suppression of ionospheric irregularities. These findings underscore the vulnerability of GPS in equatorial regions during high solar activity. GPS users, especially in precision-demanding sectors such as agriculture, aviation, and surveying, should integrate enhanced ionospheric models and mitigation strategies to maintain accuracy and operational reliability.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-22"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646094","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}
Mohammad Alibakhshikenari;Iftikhar ud Din;Nouf Abd Elmunim;Bal S. Virdee;Sunil Kumar;Sadiq Ullah;Muhammad Akmal Chaudhary;Nisar Ahmad Abbasi;Chan Hwang See;Ernesto Limiti;Takfarinas Saber
This paper presents a novel multiport antenna tailored for 5G millimeter-wave (mm-Wave) applications. The proposed design features orthogonally arranged radiating elements to ensure compactness with an overall footprint of just 20 × 26 mm2. A key innovation is the integration of a frequency selective surface (FSS) layer placed above the antenna system to enhance gain and isolation without increasing complexity. This FSS enhances gain by 1.5 dB across the band, achieving apeak gain of 7.5 dBi at 41 GHz. The antenna operates across the entire Ka-band (22–46 GHz), delivering efficiency exceeding 80% and maintaining isolation above 20 dB. Key multiport antenna performance parameters including diversity gain (DG = 10) and envelope correlation coefficient (ECC <0.005) align with performance benchmarks, and experimental measurements validate simulation results. The unique combination of orthogonal element placement and FSS enhancement positions this antenna as a robust solution for next-generation 5G applications.
{"title":"High-performance multiport antenna with frequency selective surface for 5G Ka-band applications","authors":"Mohammad Alibakhshikenari;Iftikhar ud Din;Nouf Abd Elmunim;Bal S. Virdee;Sunil Kumar;Sadiq Ullah;Muhammad Akmal Chaudhary;Nisar Ahmad Abbasi;Chan Hwang See;Ernesto Limiti;Takfarinas Saber","doi":"10.1029/2025RS008350","DOIUrl":"https://doi.org/10.1029/2025RS008350","url":null,"abstract":"This paper presents a novel multiport antenna tailored for 5G millimeter-wave (mm-Wave) applications. The proposed design features orthogonally arranged radiating elements to ensure compactness with an overall footprint of just 20 × 26 mm<sup>2</sup>. A key innovation is the integration of a frequency selective surface (FSS) layer placed above the antenna system to enhance gain and isolation without increasing complexity. This FSS enhances gain by 1.5 dB across the band, achieving apeak gain of 7.5 dBi at 41 GHz. The antenna operates across the entire Ka-band (22–46 GHz), delivering efficiency exceeding 80% and maintaining isolation above 20 dB. Key multiport antenna performance parameters including diversity gain (DG = 10) and envelope correlation coefficient (ECC <0.005) align with performance benchmarks, and experimental measurements validate simulation results. The unique combination of orthogonal element placement and FSS enhancement positions this antenna as a robust solution for next-generation 5G applications.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-18"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646095","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}
Amenah Shabeeb Kamil;Esraa Mousa Ali;Mohammad Alibakhshikenari;Mohammad Tariqul Islam;Bal Virdee;Dion Mariyanayagam;Nisar Ahmad Abbasi;Nasr Rashid;Taha A. Elwi
This paper demonstrates the performance enhancement of a conventional planar antenna by incorporating metasurface (MTS) layer using a proposed unit-cell array. The impact of MTS unit-cell density on bit-error-rate (BER) and channel capacity (CC) in a point-to-point microwave link is investigated. The MTS layer is constructed from an array of identical unit-cells, including circular, square, and Jerusalem cross microstrip-line elements. The proposed H-shaped checkerboard antenna design is integrated with the MTS and evaluated for various unit-cell densities. Analytical scrutiny reveals significant enhancements in BER and CC with higher MTS unit-cell density, along with an increase in antenna gain through optimal MTS placement. This improvement is attributed to the MTS's ability to concentrate radiated energy within a narrower spatial region, optimizing signal transmission. Experimental validation shows a strong correlation between analytical predictions and measured results, confirming the effectiveness of our methodology. This study not only highlights the impact of MTS configurations on wireless channel performance but also provides valuable insights into the design and optimization of future wireless communication systems.
{"title":"Metasurface effect on the performance of planar antennas for wireless communications","authors":"Amenah Shabeeb Kamil;Esraa Mousa Ali;Mohammad Alibakhshikenari;Mohammad Tariqul Islam;Bal Virdee;Dion Mariyanayagam;Nisar Ahmad Abbasi;Nasr Rashid;Taha A. Elwi","doi":"10.1029/2024RS008156","DOIUrl":"https://doi.org/10.1029/2024RS008156","url":null,"abstract":"This paper demonstrates the performance enhancement of a conventional planar antenna by incorporating metasurface (MTS) layer using a proposed unit-cell array. The impact of MTS unit-cell density on bit-error-rate (BER) and channel capacity (CC) in a point-to-point microwave link is investigated. The MTS layer is constructed from an array of identical unit-cells, including circular, square, and Jerusalem cross microstrip-line elements. The proposed H-shaped checkerboard antenna design is integrated with the MTS and evaluated for various unit-cell densities. Analytical scrutiny reveals significant enhancements in BER and CC with higher MTS unit-cell density, along with an increase in antenna gain through optimal MTS placement. This improvement is attributed to the MTS's ability to concentrate radiated energy within a narrower spatial region, optimizing signal transmission. Experimental validation shows a strong correlation between analytical predictions and measured results, confirming the effectiveness of our methodology. This study not only highlights the impact of MTS configurations on wireless channel performance but also provides valuable insights into the design and optimization of future wireless communication systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-15"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646103","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}
Y. Zhao;D. C. Jacobs;J. Bowman;T. Samson;M.-O. R. Lalonde;D. Larson
Radio frequency interference (RFI), particularly human-made RFI such as FM radio, presents a unique challenge to radio astronomy experiments at low frequencies (10-200 MHz) such as those for 21 cm cosmology and searches for exoplanet auroral emission. Current experiments aim to avoid RFI by building instruments in remote locations. However, as usage patterns change with time and radio bands become more crowded, new sites and mitigation strategies are needed. Here we report efforts toward a survey of the most isolated places on Earth, reflected in measures of human activity, including vessels, transmitter databases, and human censuses. Astronomers have also begun to consider experiments on the radio quiet lunar far side. This work bridges the development of Earth-based and lunar projects for radio astronomy. Over several locations on the planet, the RFI experienced by a space-based instrument, either in low-Earth orbit or on a high-altitude balloon, could be low enough to merit use for a full-fledged 21-cm experiment or as a staging ground for future lunar work. As a precursor to scientific use, we aim to make measurements of the low-frequency radio spectrum in low-Earth orbit. The Radio Background Experiment (RBE) is a compact radio spectrometer built using elements of the Experiment to Detect the Global Epoch of Reionization Signature ground-based global 21 cm experiment. A prototype of RBE was deployed from the International Space Station as a guest payload on the DORA cubesat in October 2024. The spacecraft re-entered rapidly due to strong solar activity but managed to acquire data indicating healthy functioning of the spectrometer components.
{"title":"Building a global map of low frequency radio interference from orbit with DORA","authors":"Y. Zhao;D. C. Jacobs;J. Bowman;T. Samson;M.-O. R. Lalonde;D. Larson","doi":"10.1029/2025RS008236","DOIUrl":"https://doi.org/10.1029/2025RS008236","url":null,"abstract":"Radio frequency interference (RFI), particularly human-made RFI such as FM radio, presents a unique challenge to radio astronomy experiments at low frequencies (10-200 MHz) such as those for 21 cm cosmology and searches for exoplanet auroral emission. Current experiments aim to avoid RFI by building instruments in remote locations. However, as usage patterns change with time and radio bands become more crowded, new sites and mitigation strategies are needed. Here we report efforts toward a survey of the most isolated places on Earth, reflected in measures of human activity, including vessels, transmitter databases, and human censuses. Astronomers have also begun to consider experiments on the radio quiet lunar far side. This work bridges the development of Earth-based and lunar projects for radio astronomy. Over several locations on the planet, the RFI experienced by a space-based instrument, either in low-Earth orbit or on a high-altitude balloon, could be low enough to merit use for a full-fledged 21-cm experiment or as a staging ground for future lunar work. As a precursor to scientific use, we aim to make measurements of the low-frequency radio spectrum in low-Earth orbit. The Radio Background Experiment (RBE) is a compact radio spectrometer built using elements of the Experiment to Detect the Global Epoch of Reionization Signature ground-based global 21 cm experiment. A prototype of RBE was deployed from the International Space Station as a guest payload on the DORA cubesat in October 2024. The spacecraft re-entered rapidly due to strong solar activity but managed to acquire data indicating healthy functioning of the spectrometer components.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-8"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646098","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 investigates how cosmic ray intensity (CRI) responds to major geomagnetic storms in 2024, utilizing data from six high-latitude neutron monitor (NM) stations and solar wind parameters from the OMNI database. An event-aligned Superposed Epoch Analysis (SEA) framework, using ±2-day windows centered at the Dst minimum, consistently reveals Forbush Decreases (FDs) in CRI, with onset timing and depth influenced by storm intensity and station location. A strong inverse correlation between CRI and the Akasofu parameter (ε) indicates that cosmic ray access to near-Earth space decreases as solar wind energy input increases. The pressure-corrected Dst index (Dst∗) also shows significant anti-correlation with CRI, consistent with enhanced geomagnetic shielding during ring current intensification. Wavelet Transform Coherence analysis confirms statistically significant coupling between CRI and ε, Dst∗, the Alfvén Mach number, and the magnetosonic Mach number (MMN), especially within the 6-24 hr period range. During superstorms, coherence is intense and persistent, with ε and MMN leading CRI suppression at diurnal scales. Rigidity-dependent analysis shows that peak CRI depression increases at lower cutoff rigidities, supporting the role of geomagnetic filtering during storm conditions. These findings show that a combination of solar wind drivers and internal magnetospheric dynamics shapes storm-time CRI responses.
{"title":"Solar wind energy coupling and cosmic ray intensity: A study of key solar parameters","authors":"Chali Idosa Uga;Chali Yadeta Goshu;Kebede Shogile Rikitu","doi":"10.1029/2025RS008233","DOIUrl":"https://doi.org/10.1029/2025RS008233","url":null,"abstract":"This study investigates how cosmic ray intensity (CRI) responds to major geomagnetic storms in 2024, utilizing data from six high-latitude neutron monitor (NM) stations and solar wind parameters from the OMNI database. An event-aligned Superposed Epoch Analysis (SEA) framework, using ±2-day windows centered at the Dst minimum, consistently reveals Forbush Decreases (FDs) in CRI, with onset timing and depth influenced by storm intensity and station location. A strong inverse correlation between CRI and the Akasofu parameter (ε) indicates that cosmic ray access to near-Earth space decreases as solar wind energy input increases. The pressure-corrected Dst index (Dst∗) also shows significant anti-correlation with CRI, consistent with enhanced geomagnetic shielding during ring current intensification. Wavelet Transform Coherence analysis confirms statistically significant coupling between CRI and ε, Dst∗, the Alfvén Mach number, and the magnetosonic Mach number (MMN), especially within the 6-24 hr period range. During superstorms, coherence is intense and persistent, with ε and MMN leading CRI suppression at diurnal scales. Rigidity-dependent analysis shows that peak CRI depression increases at lower cutoff rigidities, supporting the role of geomagnetic filtering during storm conditions. These findings show that a combination of solar wind drivers and internal magnetospheric dynamics shapes storm-time CRI responses.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"60 11","pages":"1-21"},"PeriodicalIF":1.5,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145646097","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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