Satellite Applications Research Articles

Utilizing the Achievements of Data Acquiring Solution and Cloud Service Platform for China-Africa Cooperation on Satellite Remote Sensing Application

Abstract. This study examines the collaborative approach in China-Africa satellite remote sensing initiatives based on solutions of satellite data acquiring, sharing and application experiences. It specifically addresses the data coverage requirements and current coverage scenarios of China's natural resources land satellites in Africa. By establishing the China-Africa Cooperation Centers on Satellite Remote Sensing Application, adopting a multi-level distributed technology center model, and implementing cross-continental remote sensing cloud services through an internet-based cloud platform, this initiative aims to enhance the direct utilization of satellite data in Africa. Furthermore, strategic satellite observation window designs tailored to seasonal changes have increased the frequency of valid coverage over the entire African continent to at least once a year. Such advancements pave the way for real-time monitoring applications, particularly in crucial areas such as sustainable development projects and disaster response efforts. Therefore, the study also provides some useful case studies that are anchored on the Sustainable Development Goals.

Flat double-layer metal-only metasurface with polarization-dependent operation in a C/X dual band

In this communication, a dual-band, orthogonal polarization transmission metasurface antenna operating at 6.5 GHz and 9.5 GHz is proposed. The element of this transmitarray is composed of only two identical layers of metal plates, with air medium filling the space between the upper and lower layers. Each layer has four sets of staggered I-slots, thus ensuring dual-frequency orthogonal polarization operation. Moreover the proposed element overcomes the challenge of achieving full 360-degree phase shift in dual-layer metal-only structures without any additional connecting elements. By altering the length of the slots, it can achieve a continuous full 360-degree phase shift while maintaining a transmission amplitude above −2 dB and exhibits co-polarized transmission in both bands. Then a prototype containing 16 × 16 elements is designed and fabricated to verify the feasibility of the design scheme. The measurement results, which are consistent with the simulation, demonstrate that the maximum gains of 24.85 and 27.64 dBi are obtained at 6.4 GHz and 9.4 GHz, with corresponding aperture efficiencies of 23.18% and 20.4% and a 3-dB gain bandwidth of 15.6% and 22.34%. The good transmission coefficients of the element and the dual-band capability make the design a competitive candidate for satellite and high-power applications.

Current Status of Satellite Development and Application

Current Status of Satellite Development and Application

Multifunctional Double Band Mesh Antenna with Solar Cell Integration for Communications Purposes

A dual band flexible antenna based on a circularly polarized modified meshed patch antenna design. This article focuses on some of the most pressing issues in small satellite applications. The antenna optimization and improvement of antenna performance, such as radiation efficiency. As is well known, circular polarization is immune to the Faraday rotation effect in the ionosphere and can thus prevent a 3-dB loss in geo-satellite communication. With the use of the software program Computer Simulation Technology (CST), the proposed circularly polarized modified meshed patch antenna has been created. Therefore, this article also presents a modified design of a circularly polarized meshed patch antenna to reduce the complexity of the antenna and decrease the size as much as it is capable. However, a meshed patch antenna can support a high communication data rate. The antenna architecture will theoretically be consistent with the installation of solar panels. The antenna utilizes a conductive copper as the core material and the substrate using flexible polyimide. The design antenna is very small, having an overall size of 30 * 30 mm when compared to other conventional non-transparent antenna operating at the same frequencies of 2.6, 3.5 GHz. The antenna that is proposed involves two meshed patch elements of same size but in various shapes. Finally, the proposed antenna is integrated into a solar cell by using the amorphous silicon thin film.

Analysis of multipath effects on Low Earth Orbit navigation satellites

Abstract With the large-scale emergence of Low-Earth Orbit (LEO) internet constellations, the direct or indirect utilization of LEO communication constellations for navigation and positioning has become a hot topic of current research. However, the multipath effect remains a critical factor influencing positioning accuracy. Compared to traditional Medium-Earth Orbit (MEO) satellites, LEO satellites move swiftly, resulting in faster multipath variations, which renders traditional multipath envelope analysis methods inapplicable. This study proposes a novel analytical model tailored to the multipath effect characteristics of LEO satellites. Through this model, we have observed that the multipath variations of high-frequency signals in LEO rapidly fluctuate near zero, offering the potential to reduce errors through smoothing methods. Furthermore, the study reveals that the impact of the multipath effect is positively correlated with orbital altitude and inversely correlated with carrier frequency. This study provides a new perspective for understanding the multipath effect characteristics of LEO satellites and offers necessary theoretical support and practical guidance for improving the accuracy of navigation and positioning systems based on LEO satellites. Future research can further explore multipath suppression methods and promote the widespread application of LEO satellites in the field of navigation and positioning.

Security in data-driven satellite applications: An overview and new perspectives

Security in data-driven satellite applications: An overview and new perspectives

Dual-dielectric Fabry-Perot film for visible-infrared compatible stealth and radiative heat dissipation

Multiband camouflage of space satellite to against advanced detection has attracted rising attention. However, the combination of compatible camouflage and radiative heat dissipation for space satellite still remains challenging, which requires low visibility and selective thermal emission in a dark and deep cold background. In this work, a dual dielectric Ge/SiO2 layer embedded Fabry-Perot multilayer film (W/Ge/SiO2/W/SiO2) is proposed for space stealth and heat dissipation. Ge and SiO2 films with appropriate thickness are designed to realize high visible absorption and spectra selective IR emission, simultaneously. The optimized multilayer film achieves a high absorbance (α = 0.983) in visible light (0.38–0.80 μm) for visible stealth, low emissivity (ε3–5 μm = 0.038; ε8–14 μm = 0.200) in atmospheric windows for infrared stealth, and relative high emissivity outside the atmospheric windows (ε5–8 μm = 0.487) for radiative heat dissipation. The simulation results indicate that the coupling of tunneling effect in ultrathin metallic W film and Fabry-Perot resonant is the main contribution to the excellent absorptivity and emissivity tunability. The proposed dual spacers embedded Fabry-Perot multilayer film paves a new way for multispectral camouflage of space satellite and other applications such as solar-thermal conversion, thermal management, energy saving, and detective technologies.

A Multi-Pointer Network for Multiple Agile Optical Satellite Scheduling Problem

With the rapid growth in space-imaging demands, the scheduling problem of multiple agile optical satellites has become a crucial problem in the field of on-orbit satellite applications. Because of the considerable solution space and complicated constraints, the existing methods suffer from a huge computation burden and a low solution quality. This paper establishes a mathematical model of this problem, which aims to maximize the observation profit rate and realize the load balance, and proposes a multi-pointer network to solve this problem, which adopts multiple attention layers as the pointers to construct observation action sequences for multiple satellites. In the proposed network, a local feature-enhancement strategy, a remaining time-based decoding sorting strategy, and a feasibility-based task selection strategy are developed to improve the solution quality. Finally, extensive experiments verify that the proposed network outperforms the comparison algorithms in terms of solution quality, computation efficiency, and generalization ability and that the proposed three strategies significantly improve the solving ability of the proposed network.

Enhancing Surface Water Monitoring through Multi-Satellite Data-Fusion of Landsat-8/9, Sentinel-2, and Sentinel-1 SAR

Long revisit intervals and cloud susceptibility have restricted the applicability of earth observation satellites in surface water studies. Integrating multiple satellites offers potential for more frequent observations, yet combining different satellite sources, particularly optical and SAR satellites, presents complexities. This research explores the data-fusion potential and limitations of Landsat-8/9 Operational Land Imager (OLI), Sentinel-2 Multispectral Instrument (MSI), and Sentinel-1 Synthetic Aperture (SAR) satellites to enhance surface water monitoring. By focusing on segmented surface water images, we demonstrate that combining optical and SAR data is generally effective and straightforward using a simple statistical thresholding algorithm. Kappa coefficients(κ) ranging from 0.80 to 0.95 indicate very strong harmony for integration across reservoirs, lakes, and river environments. In vegetative environments, integration with S1SAR shows weak harmony, with κ values ranging from 0.27 to 0.45, indicating the need for further studies. Global revisit interval maps reveal significant improvement in median revisit intervals from 15.87 to 22.81 days using L8/9 alone, to 4.51 to 7.77 days after incorporating S2, and further to 3.48 to 4.62 days after adding S1SAR. Even during wet season months, multi-satellite fusion maintained the median revisit intervals to less than a week. Maximizing all available open-source earth observation satellites is integral for advancing studies requiring more frequent surface water observations, such as flood, inundation, and hydrological modeling.

Investigation of urban low-altitude long-range atmospheric links for FSO coherent communication

Due to the complexity of low-altitude atmospheric channel conditions, the commercial application of FSO communication systems is less prevalent than satellite applications. This is mainly because there is a trade-off between achieving system stability through active compensation technology and maintaining low costs. Different application scenarios and atmospheric channel states correspond to different optimal structural parameter selections, which is crucial for low-cost FSO systems without complex compensation mechanisms. Therefore, measuring actual channel conditions is essential. One existing issue is that current research does not sufficiently discuss the connection between theoretical analysis and practical experiments in FSO communication, thus, establishing models and analysis methods is necessary that can accurately predict the performance of actual FSO atmospheric communication systems. We have developed a comprehensive FSO model to evaluate the effects of channel and structural factors on system performance. This model is vital for cost-effective parameter selection in system design and for analyzing actual system performance. Additionally, we established 6.6 km and 12.7 km FSO transmission links in an urban low-altitude environment. Subsequently, we conducted tests on atmospheric attenuation, channel statistical characteristics, and DPSK/QPSK coherent communication performance. Based on the analysis that combines experiments with theory, we have deduced the atmospheric attenuation of FSO links. The channel statistical characteristics provided the statistical properties of the two links under weak, moderate, and strong turbulence, along with fitting curves. Long-term channel statistical experiments indicate that the channel is most stable during the early morning hours of the day, and the 12.7 km communication experiment without turbulence correction technology is only feasible at this time. Furthermore, we presented a method for using theory to evaluate the performance of actual FSO systems in random atmospheric channels.

Circular Microstrip Patch Antenna : Design, Simulation, and Analysis For 5G Applications

Microstrip Patch Antennas (MPA) have emerged as a remarkable discovery in the period of miniaturization, despite the fact that advancements in antenna engineering have resulted in the fast growth of communication networks. This work encompasses the design, modelling, and analysis of circular microstrip patch antennas. The resonant frequency of the recommended patch antennas is 9 GHz, which is within the X band range. Ansys HFSS software was used to create them using Rogers RT/duroid 5880 material, which has a dielectric constant of 2.2. Five performance measures were utilized to examine the recommended MPAs: return loss, bandwidth, VSWR, gain, and HPBW. The required information refers to the measurements of return loss, voltage standing wave ratio (VSWR), and half power beamwidth (HPBW). The recommended antennas are ideal for use in radar, wireless, and satellite applications.

Millimeter micro‐coaxial beam steering array for high‐speed satellite communications

AbstractWide‐band low‐loss passive beam steering array presents to be essential part of the RF front‐ends for high‐speed detection during deep space exploration missions. In this letter, the copper‐based additive manufacturing technology is proposed for the implementation of low‐profile (~0.1λ) antenna design. Adopting the micro‐coaxial line as the basic design unit enables wide bandwidth design. In addition, the broadband designs of Butler matrix, planar antenna element, and transmission transitions are proposed, respectively. The miniaturization of the metallic patch antenna is realized using a double slotted design, ensuring an array space of ~0.5λ, which beneficial for the low‐lobe beam steering. Experimental results show that the antenna array with an overall size of 39 × 29 × 0.5 mm presents four beams located at ±14° and ±43°, respectively. The bandwidth of return loss better than −10 dB ranges from 65 to 71 GHz. The measured result matches well with the simulated ones, which makes its potential operation for satellite applications.

Wideband Dual Circularly Polarized Helical Antenna Array for Satellite Applications

Wideband Dual Circularly Polarized Helical Antenna Array for Satellite Applications

A Broadband MS-Based Circularly Polarized Antenna Array Using Sequential-Phase Feeding Network.

This paper introduces the design of a circularly polarized metasurface-based antenna array for C-band satellite applications that owns broadband operation and high gain characteristics. The single radiating element comprises a Y-shape patch and an above-placed 2 × 2 unit-cell metasurface. Further improvement in operating bandwidth and broadside gain is achieved by arranging four single elements in a 2 × 2 configuration and a sequential-phase feed network. A prototype has been fabricated and measured to validate the feasibility of the proposed antenna array. The measured operating bandwidth is 20% (4.50-5.50 GHz), which is an overlap between a -10 dB impedance bandwidth of 29.8% (4.50-5.99 GHz) and a 3 dB axial ratio bandwidth of 20% (4.50-5.50 GHz). Across this operating band, the peak broadside gain is 10.5 dBi. Compared with the recently published studies, the proposed array is a prominent design for producing a wide operating bandwidth and relatively high gains while maintaining the overall compact dimensions.

An Investigation on Causes of the Detected Surface Solar Radiation Brightening in Europe Using Satellite Data

AbstractSurface solar radiation is fundamental for terrestrial life. It provides warmth to make our planet habitable, drives atmospheric circulation, the hydrological cycle and photosynthesis. Europe has experienced an increase in surface solar radiation, termed “brightening,” since the 1980s. This study investigates the causative factors behind this brightening. A novel algorithm from the EUMETSAT satellite application facility on climate monitoring (CM SAF) provides the unique opportunity to simulate surface solar radiation under various atmospheric conditions for clouds (clear‐sky or all‐sky), aerosol optical depth (time‐varying or climatological averages) and water vapor content (with or without its direct influence on surface solar radiation). Through a multiple linear regression approach, the study attributes brightening trends to changes in these atmospheric parameters. Analyzing 61 locations distributed across Europe from 1983 to 2020, aerosols emerge as key driver during 1983–2002, with Southern Europe and high elevations showing subdued effects (0%/decade–1%/decade) versus more pronounced impacts in Northern and Eastern Europe (2%/decade–6%/decade). Cloud effects exhibit spatial variability, inducing a negative effect on surface solar radiation (−3%/decade–−2%/decade) at most investigated locations in the same period. In the period 2001–2020, aerosol effects are much smaller, while cloud effects dominate the observed brightening (2%/decade–5%/decade). This study therefore finds a substantial decrease in the cloud radiative effect over Europe in the first two decades of the 21st century. Water vapor exerts negligible influence in both sub‐periods.

High-resolution mapping of urban Aedes aegypti immature abundance through breeding site detection based on satellite and street view imagery

Identification of Aedes aegypti breeding hotspots is essential for the implementation of targeted vector control strategies and thus the prevention of several mosquito-borne diseases worldwide. Training computer vision models on satellite and street view imagery in the municipality of Rio de Janeiro, we analyzed the correlation between the density of common breeding grounds and Aedes aegypti infestation measured by ovitraps on a monthly basis between 2019 and 2022. Our findings emphasized the significance (p ≤ 0.05) of micro-habitat proxies generated through object detection, allowing to explain high spatial variance in urban abundance of Aedes aegypti immatures. Water tanks, non-mounted car tires, plastic bags, potted plants, and storm drains positively correlated with Aedes aegypti egg and larva counts considering a 1000 m mosquito flight range buffer around 2700 ovitrap locations, while dumpsters, small trash bins, and large trash bins exhibited a negative association. This complementary application of satellite and street view imagery opens the pathway for high-resolution interpolation of entomological surveillance data and has the potential to optimize vector control strategies. Consequently it supports the mitigation of emerging infectious diseases transmitted by Aedes aegypti, such as dengue, chikungunya, and Zika, which cause thousands of deaths each year.

A new miniaturized Split-Ring Resonator-Based inverse double Sigma-Shaped artificial material for Penta-Band wireless communication

This paper discusses a study on creating and confirming the authenticity of an artificial material with a SNG (Singular Negative) attribute. The artificial material was constructed using a metamaterial structured around split-ring resonators forming an inverse double sigma shape. Advanced electromagnetic simulation tools like CST (Computer Simulation Technology) Microwave Studio, Ansys HFSS (High Frequency Structure Simulator) and ADS (Advanced Design System) were employed to extensively analyze the electromagnetic characteristics of the artificial material. Notably, the proposed artificial material exhibits five distinct resonance frequencies spanning L-, S-, C-, X-, and Ku-band operations, specifically at 1.560 GHz, 2.232 GHz, 4.350 GHz, 8.095 GHz, and 17.370 GHz. Achieving an optimal EMR (Effective Medium Ratio) of 23.45, with a compact unit cell size of 8.2 mm × 8.2 mm and a substrate thickness of 1.905 mm, underscores its innovative design attributes. Of significance, the compact size, SNG characteristics, high EMR, and resonant frequencies render this structure particularly noteworthy. The utilization of the L-band for GPS (Global Positioning System), S-band for Wireless LAN (Local Area Network), C-band for Satellite communication, X-band radar system, and the Ku-band for VSAT (Very Small Aperture Terminal) communication applications is well-documented. This article elucidates the intricacies of the design process and conducts various parametric analyses. Remarkably, the simulation results obtained from Ansys HFSS 3D software closely align with those from CST. Furthermore, a comprehensive examination of surface current, E-field, and H-field distributions is provided. Importantly, comparative assessments indicate the superior performance of the proposed structure across multiple metrics, including EMR, SNG frequency range, and compactness, positioning it as an ideal candidate cellular phone, satellite, and radar-based applications.

A substrate-integrated waveguide-based wideband circularly polarized slot antenna using the parasitic square patch array

In this paper, a planar low-profile wideband circularly polarized substrate-integrated waveguide (SIW) based antenna is investigated. The antenna comprises two substrates stacked over each other. The top layer of the antenna is loaded with a 4 × 4 array of parasitic square patches stacked over a spiral slot loaded in the SIW cavity. The spiral slot is utilized for the generation of narrow band circular polarization and to enhance the CP bandwidth, the parasitic patch array is excited through the electromagnetic coupling mechanism without any air gap between them. The antenna is fabricated and tested to validate the simulated results. A wide relative impedance bandwidth of 33% (8.25–11.55 GHz) and the axial ratio bandwidth of 8.55–9.70 GHz (12.60%) is exhibited. The broadside radiation characteristics are achieved with peak gain of 8.05dBic at 9 GHz. The overall size of the antenna structure is 0.8λ0 × 0.8λ0. The proposed antenna is suitable for various satellite applications.

Multidimensional Evaluation of Altimetry Marine Gravity Models with Shipborne Gravity Data from a New Platform Marine Gravimeter

With the development of satellite altimetry technology and the application of new altimetry satellites, the accuracy and resolution of altimeter-derived gravity field models have improved over the last decades. Nowadays, they are close enough to shipborne gravimetry. In this paper, multi-source shipborne gravity data in the South China Sea were taken to evaluate the accuracies of two high-precision altimeter-derived marine gravity field models (SS V30.1, DTU17). In these shipborne gravity data, there are dozens of routes’ ship gravimetry data, obtained from the National Geophysical Data Center (NGDC); data were tracked from a marine survey with a commercial marine gravimeter (type KSS31M), and data were tracked from a marine gravimetry campaign that was conducted with a newly developed platform gravimeter (type JMG) in the South China Sea in September 2020. After various data filtering, processing, and calibrations, the shipborne gravity data were validated with crossover points analysis. Then, the processed shipborne data were employed to evaluate the accuracy of the altimeter-derived marine gravity field models. During this procedure, the quality of JMG shipborne gravity data was compared with the results of KSS31M and NGDC data. Analysis and evaluation results show that the crossover points verification accuracies of KSS31M and JMG are 0.70 mGal and 1.61 mGal, which are much better than the accuracy of NGDC, which is larger than 8.0 mGal. In the area where the bathymetry changes slowly, the root mean square error values between altimetry gravity models and KSS31M data are respectively 3.28 mGal and 4.54 mGal, and those of the JMG data are respectively 2.94 mGal and 2.60 mGal. According to the above results, we can conclude that the JMG has the same 1–2 mGal accuracy level as KSS31M and can meet the measurement requirements of marine gravity.

Operational application of Fengyun geostationary meteorological satellites to cloud observation products

Cloud products from geostationary satellites are the main alternative to surface synoptic cloud observations (SYNOP), and have become the baseline products for the development and construction of the Quality Management System (QMS) of integrated meteorological observation in China. This study addresses the needs of the China Meteorological Administration (CMA) for such an operational reform, and it is carried out using real-time observations obtained from the Fengyun-2E (FY-2E) geostationary satellite in 2012 to derive cloud total amount and classification using two different methods. Compared to surface SYNOP observations, the cloud total amount estimated by FY-2E is generally significantly lower (about 30% lower on average). The cloud classification resulting from the two methods used in this study is also significantly different from the classification obtained from surface observations (difference between 22 and 32%). The difference is smaller for the classification method, which uses additional auxiliary temperature profiles.