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Defected ground structure (DGS) based MIMO antenna array with decent isolation characteristics for satellite communications in unified S-band (USB) 基于缺陷地面结构(DGS)的具有良好隔离特性的MIMO天线阵列用于统一s波段(USB)卫星通信
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008379
Avishek Chakraborty;Ravi Shankar Saxena;Indrasen Singh;Jatinder Kaur;Ramneet Kaur;Rishiv Kalia;D. Durga Bhavani
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.
本研究的重点是为移动卫星服务(MSS)开发一种高效、高隔离的多输入多输出(MIMO)天线阵列。s波段(2-4 GHz)的一部分(2-4 GHz)范围为2至2.2 GHz,称为统一s波段(USB),用于MSS,特别是用于空间到地球通信。所提出的MIMO的最终目标是覆盖USB频谱并在2.2 GHz谐振。作为设计过程的第一步,设计了在期望频段内具有良好辐射特性的弯曲线单极子贴片。然后,将所提出的ML辐射体的镜像加入到设计中,形成双元ML- mimo阵列。设计良好的MIMO对提高下一代通信的可靠性、信道容量和频率重用非常有益。但同时,它固有地增加了紧密放置的散热器之间的耦合效应,这可能会降低整体设计的性能。为了克服耦合效应,在ML-MIMO的局部地平面上提出了缺陷地结构(DGS)。所提出的DGS旨在通过扰动部分地平面的表面电流分布来减小耦合效应。同时,DGS还通过提高增益和降低总重量来提高整个结构的紧凑性。MIMO参数指标,如轴比低于3db,包络相关系数小于0.0005,分集增益接近10,也旨在同时将标准MIMO应用的互耦合降低到- 30 dB以下,回波损耗降低到- 25 dB以下。然后在尺寸为40mm × 48mm的FR4基板上制造ML-MIMO,并进行测量。模拟结果与实测结果非常接近。为了进一步验证,还提出了与其他当代研究相关的详细比较和权衡分析。
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引用次数: 0
Analysis of parallel-plate T-junctions using the method of Kobayashi potential 用小林电势法分析平行板t型结
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008429
B. Honarbakhsh
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.
利用小林势(Kobayashi Potential, KP)的方法对充气平行板t型结进行了严密的分析。与之前关于该主题的报告相比,保证了解决方案中包含相应的边缘条件。从而保证了解的唯一性。提出了一种系统的散射参数提取方法,并与实测结果进行了比较。此外,对所需谱积分的积分路径的可能选择进行了严格的讨论,并利用残数演算给出了相应的闭型解。
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引用次数: 0
Investigation of ionospheric scintillation occurrence and the impact on GNSS positioning accuracy in Kenya 肯尼亚电离层闪烁现象及其对GNSS定位精度影响的研究
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008262
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.
本研究首次分析了电离层闪烁对肯尼亚不同太阳周期阶段全球定位系统(GPS)精度的影响。来自内罗毕大学(1.3°S, 36.8°E,倾角- 22.9°)的数据分析了2009年至2012年间地磁平静期和选定的扰动期。重点是夜间(1800-0600 LT),此时低纬度电离层等离子体的不稳定性最为明显。这些不稳定性在不同尺度上产生不规则性,这反过来又通过引起信号闪烁增加了跨电离层无线电信号退化的脆弱性。根据振幅闪烁指数(S4)测量,闪烁分为强(S4 > 0.3)、中(0.2≤S4≤0.3)和弱(0.1≤S4≤0.2)。强烈闪烁在春分时最为频繁,对应的平均定位误差在水平方向上约为4米,在垂直方向上约为8米。中度闪烁的平均水平误差约为2.5 m,垂直误差约为6 m,而弱闪烁或无闪烁的平均水平误差约为1 m,垂直误差约为4 m。定位误差的严重程度随着太阳活动的增加而增加,2009年最小,2012年达到峰值。风暴时间分析表明,风暴强度、时间和相关电场,特别是快速穿透(ppef)和扰动发电机(DDEFs),强烈影响电离层不规则性的发展或抑制。这些发现强调了在太阳活动高时,GPS在赤道地区的脆弱性。GPS用户,特别是农业、航空和测量等对精度要求很高的部门的用户,应结合增强的电离层模型和减缓战略,以保持精度和操作可靠性。
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引用次数: 0
High-performance multiport antenna with frequency selective surface for 5G Ka-band applications 具有频率选择表面的高性能多端口天线,用于5G ka波段应用
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008350
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.
本文提出了一种为5G毫米波(mm-Wave)应用量身定制的新型多端口天线。提议的设计以正交布置的辐射元素为特征,以确保紧凑性,总占地面积仅为20 × 26 mm2。一个关键的创新是集成频率选择表面(FSS)层置于天线系统之上,以提高增益和隔离,而不会增加复杂性。该FSS在整个频段内的增益提高了1.5 dB,在41 GHz时实现了7.5 dBi的峰值增益。该天线工作在整个ka波段(22-46 GHz),提供超过80%的效率,并保持20 dB以上的隔离。包括分集增益(DG = 10)和包络相关系数(ECC <0.005)在内的关键多端口天线性能参数符合性能基准,实验测量验证了仿真结果。正交元件放置和FSS增强的独特组合使该天线成为下一代5G应用的强大解决方案。
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引用次数: 0
Metasurface effect on the performance of planar antennas for wireless communications 超表面效应对无线通信平面天线性能的影响
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2024RS008156
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.
本文论证了利用所提出的单元阵列将超表面(MTS)层加入传统平面天线的性能增强。研究了点对点微波链路中MTS单元密度对误码率和信道容量的影响。MTS层由一组相同的单元构成,包括圆形、方形和耶路撒冷交叉微带线元素。提出的h形棋盘天线设计与MTS集成,并评估了不同的单元密度。分析分析表明,更高的MTS单元密度显著增强了BER和CC,同时通过优化MTS放置增加了天线增益。这种改进是由于MTS能够将辐射能量集中在更窄的空间区域内,从而优化了信号传输。实验验证表明,分析预测和测量结果之间存在很强的相关性,证实了我们方法的有效性。这项研究不仅强调了MTS配置对无线信道性能的影响,而且为未来无线通信系统的设计和优化提供了有价值的见解。
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引用次数: 0
Front matters 前面问题
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1002/rds.21335
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引用次数: 0
Building a global map of low frequency radio interference from orbit with DORA 用DORA构建来自轨道的低频无线电干扰的全球地图
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008236
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.
射频干扰(RFI),特别是人为的射频干扰,如调频无线电,对低频(10-200 MHz)的射电天文学实验(如21厘米宇宙学和搜寻系外行星极光发射)提出了独特的挑战。目前的实验旨在通过在偏远地区建造仪器来避免射频干扰。然而,随着使用模式随时间的变化和无线电频段变得更加拥挤,需要新的站点和缓解策略。在这里,我们报告了对地球上最偏远地区的调查所做的努力,这些调查反映在人类活动的测量中,包括船只、发射机数据库和人口普查。天文学家也开始考虑在月球远端进行无线电安静的实验。这项工作连接了地球和月球射电天文学项目的发展。在地球上的几个地点,无论是在近地轨道上还是在高空气球上,天基仪器所经历的RFI可能足够低,值得用于成熟的21厘米实验,或者作为未来月球工作的集落地。作为科学应用的先驱,我们的目标是测量近地轨道上的低频无线电频谱。无线电背景实验(RBE)是一个紧凑的无线电光谱仪,使用该实验的元素来探测全球再电离时代特征的地面全球21厘米实验。2024年10月,RBE的原型从国际空间站作为客户有效载荷部署在DORA立方体卫星上。由于强烈的太阳活动,航天器迅速返回,但设法获得了表明光谱仪组件正常运行的数据。
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引用次数: 0
Solar wind energy coupling and cosmic ray intensity: A study of key solar parameters 太阳风能量耦合与宇宙射线强度:太阳关键参数的研究
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008233
Chali Idosa Uga;Chali Yadeta Goshu;Kebede Shogile Rikitu
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.
本文利用6个高纬度中子监测站的数据和OMNI数据库中的太阳风参数,研究了宇宙射线强度(CRI)对2024年主要地磁风暴的响应。事件对齐的叠加历元分析(SEA)框架,使用以Dst最小值为中心的±2天窗口,一致显示了CRI的Forbush衰减(FDs),其发生时间和深度受风暴强度和台站位置的影响。CRI与Akasofu参数(ε)呈强烈的负相关,表明宇宙射线进入近地空间随着太阳风能量输入的增加而减少。压力校正Dst指数(Dst∗)也与CRI呈显著的反相关,这与环电流增强时地磁屏蔽增强的结果一致。小波相干性分析证实了CRI与ε、Dst∗、alfv马赫数和磁子马赫数(MMN)之间的显著耦合,特别是在6 ~ 24 h的周期范围内。在超级风暴期间,相干性强烈且持续,ε和MMN在日尺度上主导CRI抑制。刚度相关分析表明,在较低的截止刚度下,CRI下降峰值增加,支持了风暴条件下地磁滤波的作用。这些发现表明,太阳风驱动和内部磁层动力学的结合决定了风暴时的CRI响应。
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引用次数: 0
Spectrally characterizing targets with SAR 用SAR对目标进行光谱表征
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-11-01 DOI: 10.1029/2025RS008354
Arnold D. Kim;Joseph Simpson;Chrysoula Tsogka
When target sizes are comparable to the inherent resolution of a synthetic aperture radar (SAR) imaging system, images only produce representative points which can be used to detect and locate different targets, but not distinguish any further between them. Using those representative points reconstructed with traditional SAR imaging, we introduce a method that recovers a frequency spectrum from the same set of measurements. We show theoretically that this spectrum is related to the radar cross-section of the target. For special cases when the proposed method is not able to distinctly image or recover frequency spectra from two different targets, we introduce modifications that resolve those issues. Using numerical simulations, we show that this spectrum provides valuable information allowing for differentiating targets that would otherwise be indistinguishable. Moreover, this method does not require any additional data than that already used for imaging. Including this spectral characterization opens opportunities to consider alternate strategies for managing resources for collecting and recovering target features contained in SAR measurements.
当目标尺寸与合成孔径雷达(SAR)成像系统的固有分辨率相当时,图像只产生具有代表性的点,这些点可以用来检测和定位不同的目标,而不能进一步区分不同的目标。利用传统SAR成像重建的代表性点,介绍了一种从同一组测量数据中恢复频谱的方法。我们从理论上证明,该频谱与目标的雷达截面有关。对于某些特殊情况,当所提出的方法不能清晰地成像或从两个不同的目标中恢复频谱时,我们引入了改进来解决这些问题。通过数值模拟,我们表明该光谱提供了有价值的信息,允许区分目标,否则将无法区分。此外,这种方法不需要任何额外的数据,除了已经用于成像。包括这种光谱特性,为考虑管理收集和恢复SAR测量中包含的目标特征的资源的替代策略提供了机会。
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引用次数: 0
Front matters 前面问题
IF 1.5 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS Pub Date : 2025-10-01 DOI: 10.1002/rds.21334
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引用次数: 0
期刊
Radio Science
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