Radio Science最新文献_第5页

Calibration bias evaluation and correction of S-band ground-based radar reflectivity using Ku-band space borne radar observations along the east coast of India 基于印度东海岸ku波段星载雷达观测的s波段地面雷达反射率定标偏差评估与校正

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008484

Shruti Saini;Subrata Kumar Das;Abhishek Kumar Jha;Yogesh K. Kolte;U. V. Murali Krishna;Sachin M. Deshpande

{"title":"Calibration bias evaluation and correction of S-band ground-based radar reflectivity using Ku-band space borne radar observations along the east coast of India","authors":"Shruti Saini;Subrata Kumar Das;Abhishek Kumar Jha;Yogesh K. Kolte;U. V. Murali Krishna;Sachin M. Deshpande","doi":"10.1029/2025RS008484","DOIUrl":"https://doi.org/10.1029/2025RS008484","url":null,"abstract":"The India Meteorological Department (IMD) has strategically deployed several S-band weather radars along India's coastal vicinity for weather monitoring. As radar reflectivity is critical for rainfall estimation, nowcasting, and numerical model assimilation, ensuring data quality is essential before use. The preferred approach is to minimize errors or compensate using offsets through relative (engineering) or absolute (reference-based) calibration. This study compares reflectivity measurements from four operational IMD S-band ground radars (GR) along India's east coast with Ku-band observations from the Global Precipitation Measurement (GPM) satellite's spaceborne radar (SR). The common volume sampled by the SR and GR is identified using the volume matching method, accounting for resolution, geometry, frequency scaling, and timing. The assessment is conducted to quantify the absolute calibration bias in GRs. Comparison with SR measurements reveals systematic mean differences in GR reflectivity ranging from − 9.4 to 0.3 dB across sites. The reflectivity bias varies by up to ±20 dB, driven by spatial and temporal variability, precipitation type, bright-band presence, and other meteorological factors affecting GR. Linear transformations and iterative methods account for calibration bias at each site, thereby improving results. The mean bias at each site is reduced to < |1| dB. Further, corrections are applied to compensate for the bias variability introduced by spatial-temporal averaging and by process-based diagnostic approaches, such as distinct corrections for convective, stratiform, and bright-band effects.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-22"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443241","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}

引用次数: 0

Anisoplanatic errors in two-wavelength adaptive optics 双波长自适应光学的各向异性误差

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008489

M. W. Hyde;M. F. Spencer;M. Kalensky

{"title":"Anisoplanatic errors in two-wavelength adaptive optics","authors":"M. W. Hyde;M. F. Spencer;M. Kalensky","doi":"10.1029/2025RS008489","DOIUrl":"https://doi.org/10.1029/2025RS008489","url":null,"abstract":"Two-wavelength adaptive optics (AO) systems sense wavefront errors using a beacon at one wavelength, while correcting for subsequent imaging or beam projection at another. Although most AO systems operate in this manner, the relevant AO literature is generally concerned with quantifying system performance at a single wavelength, effectively ignoring the two-wavelength nature of the problem. In this paper, we study the effects of anisoplanatism, or the physical separation of the beacon and transmit light, on two-wavelength AO systems for imaging and beam projection applications. We derive the piston-removed (PR) and piston-and-tilt-removed (PTR) optical-path-difference (OPD) variances including anisoplanatism, which are key metrics of AO system performance. We compare our closed-form PR and PTR OPD variances to numerical results and discuss their physical significance. In addition, we introduce the two-wavelength isoplanatic angle and show how it can be used to quickly assess two-wavelength AO system performance. At large, the analysis contained in this paper will inform the design and implementation of two-wavelength AO systems for multiple imaging and beam projection applications.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-18"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443171","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}

引用次数: 0

Front matters 前面问题

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/rds.70066

引用次数: 0

A miniaturized high-performance AMC-integrated dual band antenna for next-generation wireless communication platforms 用于下一代无线通信平台的小型化高性能amc集成双频天线

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008537

V. Rajavel;R. Ramasamy;Dibyendu Ghoshal;P. Venkatesh

{"title":"A miniaturized high-performance AMC-integrated dual band antenna for next-generation wireless communication platforms","authors":"V. Rajavel;R. Ramasamy;Dibyendu Ghoshal;P. Venkatesh","doi":"10.1029/2025RS008537","DOIUrl":"https://doi.org/10.1029/2025RS008537","url":null,"abstract":"Recent advancements in wireless communication technologies and Internet-enabled devices have accelerated the demand for compact, efficient antennas suitable for body-centric applications. This study presents a compact, high-performance dual-frequency antenna featuring an artificial magnetic conductor (AMC) surface for next-generation wireless systems. A modified gear-wheel radiating patch on top and a partial ground plane on the bottom comprise the antenna, making it a three-layer antenna. A circular patch overlays 12 radiating teeth, enabling a dual wideband response. The AMC surface comprises a 4 × 4 array of unit cells, each incorporating slotted square and rectangular patches. The unit cells exhibit double-negative (DNG) properties and operate in three frequency regions. The zero-degree reflection phase occurs at 2.5 GHz, 4.1 GHz, and 6.5 GHz. The integrated antenna covers impedance bandwidths of 71.79% (2.0–4.24 GHz) and 41.67% (5.13–7.83 GHz), encompassing key wireless frequency bands, while maintaining compact dimensions of 0.554λ<inf>0</inf> × 0.554λ<inf>0</inf> × 0.135λ<inf>0</inf> at the lowest resonant frequency. A maximal gain of 8.26 dBi, a low Specific Absorption Rate (SAR) of 0.0528 W/kg, and a high FBR of 33.85 dB at 4.1 GHz are key performance characteristics. VSWR values below 2 in both bands indicate exceptional impedance matching. Experimental validation using a Vector Network Analyzer (VNA) and an anechoic chamber confirms the modeling results. The proposed antenna, owing to its low SAR and wideband performance, is suitable for body-centric wireless systems operating in standard frequency bands such as ISM, Wi-Fi 6E, and C-band.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-20"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443256","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}

引用次数: 0

Guided collaborative position determination for air navigation signals 空中导航信号制导协同定位

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008456

J. Mao;X. Luo;W. Han;F. Luo;X. Hu;J. Wang

{"title":"Guided collaborative position determination for air navigation signals","authors":"J. Mao;X. Luo;W. Han;F. Luo;X. Hu;J. Wang","doi":"10.1029/2025RS008456","DOIUrl":"https://doi.org/10.1029/2025RS008456","url":null,"abstract":"The continuous and accurate estimation of aerial navigation target positions presents a significant challenge, primarily due to the lack of data with sufficient temporal continuity. Notably, existing research has seldom examined the impact of signal emission probability on the performance of ground-based positioning systems. To address the issues of localization stability and continuity for aerial targets, this study proposes the guided collaborative position determination (GPD) method. This approach leverages an interrogation-response principle for navigation signals to improve trajectory continuity. By actively sending ranging query signals from ground stations to elicit responses from airborne targets, the probability of signal exposure is increased, directly addressing the root cause of data discontinuity. Furthermore, a time difference of arrival localization model based on the sum of distances is established, enabling continuous positioning and tracking of multiple targets through particle filtering. Experimental results demonstrate that the GPD method significantly enhances localization accuracy for dense targets, particularly under conditions of small sample sizes. Computational analyses also indicate marked improvements in both inter-station communication and processing efficiency. This study introduces a novel approach to enhancing localization continuity for dense navigation signals and provides valuable insights for developing next-generation distributed ground-based positioning systems. Thus, the proposed method advances both theoretical understanding and engineering practice in critical domains such as airspace surveillance and unmanned aerial vehicle swarm management.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-25"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443155","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}

引用次数: 0

A unified vector electromagnetic framework for ionospheric scintillation and polarization effects in GNSS GNSS中电离层闪烁和极化效应的统一矢量电磁框架

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2026RS008605

T. Durgonics;S. S. Beeck

{"title":"A unified vector electromagnetic framework for ionospheric scintillation and polarization effects in GNSS","authors":"T. Durgonics;S. S. Beeck","doi":"10.1029/2026RS008605","DOIUrl":"https://doi.org/10.1029/2026RS008605","url":null,"abstract":"The ionosphere imposes coupled amplitude, phase, and polarization distortions on transionospheric Global Navigation Satellite System (GNSS) signals, reflecting the structure and dynamics of electron-density irregularities. Classical weak-scatter theory provides a mature framework for interpreting amplitude and phase scintillation, but these quantities have almost exclusively been treated as scalars. In contrast, the electromagnetic field is inherently vectorial: its two orthogonal polarization components carry additional information about propagation through a magnetized plasma. A unified treatment that incorporates this vector structure has been largely absent from standard GNSS scintillation analyses. This work develops a GNSS-specific Jones-Stokes electromagnetic framework that embeds Faraday rotation and its fluctuations within the same physical framework used to describe amplitude and phase scintillation. The approach yields a polarization scintillation metric derived from the detrended Faraday angle, exposes frequency-normalized relations that enable cross-band consistency checks, and provides a TEC-normalized estimator of the electron-density-weighted line-of-sight magnetic-field component—a physically consistent basis for exploring GNSS-based Faraday-rotation magnetometry. By extending scintillation analysis from scalar to vector diagnostics, this formulation reveals additional scientific opportunities for remote sensing ionospheric anisotropy, magnetic-field coupling, and irregularity morphology, and offers operational potential for improved space weather monitoring using existing GNSS infrastructure.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-28"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443174","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}

引用次数: 0

A novel approach to noise reduction in eLoran signal based on 1D-CycleGAN 基于1D-CycleGAN的eLoran信号降噪新方法

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008344

Kai Zhang;Bingqian Wang;Dengfeng Hu;Jiuxiang Gao

{"title":"A novel approach to noise reduction in eLoran signal based on 1D-CycleGAN","authors":"Kai Zhang;Bingqian Wang;Dengfeng Hu;Jiuxiang Gao","doi":"10.1029/2025RS008344","DOIUrl":"https://doi.org/10.1029/2025RS008344","url":null,"abstract":"Enhanced Loran (eLoran) system is a ground-based navigation system that plays a vital role in both strategic and civilian timing applications. However, the eLoran signal in real-world use is often noisy and distorted, making it hard to decode accurately. This paper presents a novel eLoran signal noise reduction algorithm based on Cycle-Consistent Generative Adversarial Networks (CycleGAN). The algorithm capitalizes on the inherent relationship between signals and images, applying image-based denoising techniques to a one-dimensional signal. CycleGAN includes two generators and two discriminators. It utilizes both noisy and clean signals to achieve noise reduction. This paper also uses one-dimensional convolutional neural network (lDCNNs) and dense residual blocks to enhance the network's performance. Experimental results demonstrate that the proposed algorithm performs well on analog signals with a signal-to-noise ratio (SNR) above — 7 dB, enhancing the SNR to over 17.54 dB while maintaining an information accuracy rate of above 98.96%. On analog data sets, this algorithm improved the SNR by an average of 22.03 dB. Furthermore, when tested with measured eLoran signals, the model not only eliminated signal distortion but also increased the SNR of a measured signal from 7.26 to 22.37 dB, achieving an information accuracy rate of over 97.91%.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443175","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}

引用次数: 0

On the detection of low-frequency planetary radio emission with an orbiting interferometer 用轨道干涉仪探测低频行星无线电发射

IF 1.6 4区地球科学

Radio Science Pub Date : 2026-06-01 Epub Date: 2026-07-03 DOI: 10.1029/2025RS008313

E. Rouillé;B. Cecconi;B. Segret;J. N. Girard;A. Loh

{"title":"On the detection of low-frequency planetary radio emission with an orbiting interferometer","authors":"E. Rouillé;B. Cecconi;B. Segret;J. N. Girard;A. Loh","doi":"10.1029/2025RS008313","DOIUrl":"https://doi.org/10.1029/2025RS008313","url":null,"abstract":"The magnetized planets of the outer Solar System produce kilometric radio emissions at very low frequencies (< 1 MHz). They reveal the planetary magnetic dynamics and their interaction with the solar wind. Those radio emissions can also serve as a proxy for interplanetary space weather monitoring. Space-borne radio interferometers will offer new capabilities for measuring planetary low-frequency radio emissions as they are not limited by the Earth's ionospheric cutoff (∼ 10 MHz) and can provide spatially resolved observations. This study is conducted in the context of the NOIRE—Nanosatellites for a Radio Interferometric Observatory in Space—concept study. The observation of planetary radio emissions is part of its main scientific objectives and should be achievable with an array of 50 satellites. The instrument's sensitivity is studied with a detailed description of the noises and errors involved in the measurement process. We then detail the various planetary radio components that can be studied with the given instrument design and the constraints currently known at this stage of the project. We discuss how the design may be optimized to better suit these scientific objectives, and we discuss the data volumes involved. The results suggest that NOIRE is able to produce dynamic spectra for Jupiter and Saturn with temporal and spectral resolutions good enough for phenomenological studies and long-term studies. They also suggest that Uranus' and Neptune's emissions may be detected, but with a low revisit rate (∼ 1 point every 4 hr).","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 6","pages":"1-28"},"PeriodicalIF":1.6,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148443199","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}

引用次数: 0

Taxonomy of IMT interference on aeronautical systems 航空系统中IMT干扰的分类

IF 1.5 4区地球科学

Radio Science Pub Date : 2026-04-01 Epub Date: 2026-03-01 DOI: 10.1029/2025RS008254

Valéria C. M. N. Leite;Alison Moraes

引用次数: 0

Multi-modal brain tumor detection using pertained U-Net and Siamese neural networks with Walrus optimization algorithm 基于相关U-Net和Siamese神经网络的多模态脑肿瘤检测与Walrus优化算法

IF 1.5 4区地球科学

Radio Science Pub Date : 2026-04-01 Epub Date: 2026-03-01 DOI: 10.1029/2025RS008514

Parshapa Padma;P. Ithaya Rani

{"title":"Multi-modal brain tumor detection using pertained U-Net and Siamese neural networks with Walrus optimization algorithm","authors":"Parshapa Padma;P. Ithaya Rani","doi":"10.1029/2025RS008514","DOIUrl":"https://doi.org/10.1029/2025RS008514","url":null,"abstract":"Accurate brain tumor segmentation and classification are critical for effective clinical diagnosis and treatment planning. Nevertheless, the current deep learning solutions commonly face the problem of tumor heterogeneity, poor contextual modeling, and ineffective discriminating of features. In response to these issues, this paper will present a new multi-modal brain tumor detection model, which will combine noise-conscious pre-processing Difference of Gaussian Square Kernel Filtering (D-GSKF), fine-tuning tumor segmentation, UNet, Efficient Long-Range Attention Network (U-Net-ELAN), feature extraction using Point Transformer (PiT) and Siamese Neural Networks, which are optimized through the Walrus Optimization Algorithm (SNN-WaOA). This work is important because it introduces a novel synergistic combination of long-range attention-inspired segmentation, transformer-inspired spatial feature modeling, and bio-inspired optimization to similarity-based tumor classification. The effectiveness of the suggested framework is supported by the large number of experiments performed on four benchmark data sets, including Figshare, BraTS 2020, Harvard, and Brain MRI, with the highest accuracy rate of 99.9%, the highest recall of 99.8%, and the lowest error rate of 0.1%, surpassing the results of a number of state-of-the-art methods. These findings suggest that the suggested method can be a stable and clinically useful method of automated brain tumor detection in various MRI modalities.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"61 4","pages":"1-22"},"PeriodicalIF":1.5,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147796279","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}

引用次数: 0