Satellite Services Research Articles

A Compact CPW-Fed Planar Stacked Circle Patch Antenna for Wideband Applications

The article investigates the performance of planar and compact CPW-fed microstrip patch antenna that offers 10 dB impedance bandwidth over the wide frequency range between 2.59 and 7.61 GHz. The parametric analysis of various design variables is included to acquire the final design of proposed antenna. The prototype exemplary of designed antenna is experimentally tested to obtain the return loss, VSWR, radiation response and gain characteristics. The close agreement is acquired between simulated and experimental results.The projected antenna has compact size of 0.61λ0 × 0.44λ0 × 0.027λ0 mm3 and offers a 10 dB wide impedance bandwidth of 5.02 GHz. Thus, it may be considered suitable for variety of wireless applications including WLAN, Wi-MAX, fixed satellite services, wireless point-to-point applications etc.

A compact flower slotted dual band notched ultrawideband antenna integrated with Ku band for ultrawideband, medical, direct broadcast service, and fixed satellite service applications

AbstractA compact flower slotted antenna (FSA) for dual band eliminated ultrawideband (UWB) integrated with Ku band applications is proposed. The basic FSA with modified ground structure is utilized for obtaining fractional bandwidth of 137% (3.45‐18.45 GHz). The dual band eliminated frequencies are achieved by a via hole to eliminate 5.39 to 5.90 GHz (upper WLAN band) frequencies and by utilizing symmetrical inverted L‐shaped parasitic elements to notch 7.30 to 7.75 GHz (downlink of X‐ band satellite communication link) frequencies. The FSA is having a compact size of 16 × 22 mm2 printed on low cost FR‐ 4 substrate with two band notched characteristics, nearly omnidirectional radiation characteristics and stable gain over UWB frequency range makes it suitable for portable UWB systems.

NASA Global Satellite and Model Data Products and Services for Tropical Meteorology and Climatology

Satellite remote sensing and model data play an important role in research and applications of tropical meteorology and climatology over vast, data-sparse oceans and remote continents. Since the first weather satellite was launched by NASA in 1960, a large collection of NASA’s Earth science data is freely available to the research and application communities around the world, significantly improving our overall understanding of the Earth system and environment. Established in the mid-1980s, the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), located in Maryland, USA, is a data archive center for multidisciplinary, satellite and model assimilation data products. As one of the 12 NASA data centers in Earth sciences, GES DISC hosts several important NASA satellite missions for tropical meteorology and climatology such as the Tropical Rainfall Measuring Mission (TRMM), the Global Precipitation Measurement (GPM) Mission and the Modern-Era Retrospective analysis for Research and Applications (MERRA). Over the years, GES DISC has developed data services to facilitate data discovery, access, distribution, analysis and visualization, including Giovanni, an online analysis and visualization tool without the need to download data and software. Despite many efforts for improving data access, a significant number of challenges remain, such as finding datasets and services for a specific research topic or project, especially for inexperienced users or users outside the remote sensing community. In this article, we list and describe major NASA satellite remote sensing and model datasets and services for tropical meteorology and climatology along with examples of using the data and services, so this may help users better utilize the information in their research and applications.

Improved adaptive impedance matching for RF front-end systems of wireless transceivers

In this paper an automatic adaptive antenna impedance tuning algorithm is presented that is based on quantum inspired genetic optimization technique. The proposed automatic quantum genetic algorithm (AQGA) is used to find the optimum solution for a low-pass passive T-impedance matching LC-network inserted between an RF transceiver and its antenna. Results of the AQGA tuning method are presented for applications across 1.4 to 5 GHz (satellite services, LTE networks, radar systems, and WiFi bands). Compared to existing genetic algorithm-based tuning techniques the proposed algorithm converges much faster to provide a solution. At 1.4, 2.3, 3.4, 4.0, and 5.0 GHz bands the proposed AQGA is on average 75%, 49.2%, 64.9%, 54.7%, and 52.5% faster than conventional genetic algorithms, respectively. The results reveal the proposed AQGA is feasible for real-time application in RF-front-end systems.

A new time delay calibration method to improve the service performance of RDSS in the BDS

The radio determination satellite service (RDSS) is an advantageous and unique aspect of the BeiDou Navigation Satellite System (BDS) because other satellite navigation systems do not incorporate the RDSS. Due to the ageing of RDSS equipment, there is a long-term drift in various types of RDSS equipment time delays. There are some differences in the RDSS positioning accuracy with the change in the out-station beams, which seriously affects the positioning accuracy and service capability of the RDSS system. At present, the time delay calibration method involves sending the device to the equipment verification field to remeasure the time delay, which is cumbersome and time-consuming. The service performance and availability of the RDSS system have become greatly degraded. Therefore, a simple and efficient RDSS time delay calibration method has become an important topic for the global BeiDou system. In this study, the time delays of all channels, in-station beams, and out-station beams were obtained by the O-C method (O is the measured value and C is the theoretical value). The experiments were performed using BeiDou RDSS data in continuous 8-day tests involving five RDSS users. The results showed that the time delay accuracies of the RDSS channels, in-station beams, and out-station beams were 2.37 ns, 1.63 ns, and 2.39 ns, respectively. The positioning tests were performed based on the original and adjusted delays. The mean horizontal positioning accuracy of the five RDSS users improved from 19.71 to 4.14 m, with an average increase of 77%. The positioning accuracy achieved in this paper is much better than that of 20 m in the Beijing calibration area at present.

Multiband planar antenna with CSRR loaded ground plane for WLAN and fixed satellite service applications

Abstract In this paper, a novel approach to achieve multiband antenna operation using metamaterial based resonant structures is presented. Multiband antenna operation is achieved by employment of complementary split ring resonators (CSRR) printed in the ground plane. The CSRRs resonate at different frequencies according to their optimized dimensions. Proposed approach features simple design and fabrication possibility compared to other methods of achieving multiband antenna operation such as usage of composite right/left-handed (CRLH) transmission line or split ring resonators (SRR) or CSRR around the patch surface. The proposed method is demonstrated through simulation and experimental measurements using three CSRRs with different resonant frequencies together with a tuning CSRR and a radiating patch. Contribution of different CSRRs to obtain multiple resonances have been shown by surface current plots. Measured antenna gain of 2.78, 1.27 and 3.45 dB has been obtained at frequencies of 5.25, 6.28 and 7.29 GHz respectively. The measurements done on developed antenna exhibits close agreement with the simulation results. In context with the current communication application trends involving multiple operating bands like 5G, this approach may have immense application potential since the same can be adopted to achieve compact multiband antennae operation in other frequency bands of interest.

High-Efficiency, Wideband GRIN Lenses With Intrinsically Matched Unit Cells

We present an automated design procedure for the rapid realization of wideband millimeter-wave lens antennas. The design method is based upon the creation of a library of matched unit-cells which comprise wideband impedance matching sections on either side of a phase-delaying core section. The phase accumulation and impedance match of each unit-cell is characterized over frequency and incident angle. The lens is divided into rings, each of which is assigned an optimal unit-cell based on incident angle and required local phase correction given that the lens must collimate the incident wavefront. A unit-cell library for a given realizable permittivity range, lens thickness, and unit-cell stack-up can be used to design a wide variety of flat wideband lenses for various diameters, feed elements, and focal distances. A demonstration GRIN lens antenna is designed, fabricated, and measured in both far-field and near-field chambers. The antenna functions as intended from 14 GHz to 40 GHz and is therefore suitable for all proposed 5G MMW bands, Ku- and Ka-band fixed satellite services. The use of intrinsically matched unit-cells results in aperture efficiency ranging from 31% to 72% over the 2.9:1 bandwidth which is the highest aperture efficiency demonstrated across such a wide operating band.

A novel bandwidth enhanced triple band antenna for satellite and airborne applications

<p align="justify"><span>This paper presents a novel bandwidth enhancement technique in which a passive stack of third order Sierpinski carpet fractal antenna is parasitically coupled to the driven element that is also a Sierpinski fractal of third order. Edge feeding technique is used. The passive stack placed symmetric to the driven elements provide the combined benefits of horizontal and vertical parasitic coupling, with added advantage of miniaturization contributed by fractal technology. Result of the study indicate that the antenna array provide triple band with a large inter-band separation that mitigates the effects of inter-band interference. The first band at 6.1Ghz with bandwidth of 250Mhz supports mobile wireless and fixed satellite service, the second band at 7.1Ghz with 350Mhz bandwidth supports mobile wireless, fixed wireless and fixed satellite service. The third band is at 11.6Ghz with bandwidth of 1.4Ghz and supports fixed wireless and fixed satellite services. The number of elements in the parasitic stack influence array performance in terms of bandwidth, gain and directivity. The bandwidth in the third band increased from 1.5Ghz for two-element stack to 1.7Ghz for three-element. This has an advantage over conventional antenna array, that use more active antenna elements that have the limitations of more power consumption and large space occupancy. </span></p>

ManitobaSat-1: A Novel Approach for Technology Advancement

ManitobaSat-1 is a 3U CubeSat program that is determined to advance the edges of space technology by performing things differently from traditional design strategies (see Fig.1). This will enhance access to space through novel technology development and verification and enable smaller companies to benefit from satellite services. ManitobaSat-1 is being developed at the University of Manitoba by the Space Technologies and Advanced Research Laboratory (STARLab) in collaboration with the Center for Terrestrial and Planetary Exploration at the University of Winnipeg, York University, the Interlake School Division, and Magellan Aerospace, our industrial partner.

Introduction to polar earth orbits (PEO) in the function of the satellite distress and safety systems (SDSS)

<p align="LEFT">In this paper is described introduction of Polar Earth Orbits (PEO) in the function of the Satellite Distress and Safety Systems (SDSS) for all mobile applications. The results of a technical and economic study regarding the extension of the Inmarsat Geostationary Earth Orbit (GEO) satellite system to cover polar region are reviewed. In addition, also are examined the technical and practical aspects of providing an operational polar Mobile Satellite Service (MSS) for the provision of combined distress and safety communication solutions in conjunction with a commercial and defense communication systems for maritime, land and aeronautical applications. This study is considered several PEO satellite models and their probable costs for Search and Rescue (SAR) and determination MSS solutions. The practical usage of Low PEO constellation is realized by Cospas-Sarsat international project for SDSS.</p>

Interference Mitigation using Adaptive Beamforming with RLS Algorithm for Coexistence between 5G and Fixed Satellite Services in C-Band

Smart antenna system is one of the most suitable techniques making the sharing between incumbent Fixed Satellite Services (FSS) and the Fifth Telecommunication Generation (5G) possible, because adaptive beamforming can make null the beam towards the FSS earth station. This paper proposes the use of Recursive Least Square (RLS) algorithm for adaptive beamforming in 5G Base Station (BS) having a null beam toward FSS earth station. We perform a computer simulation to evaluate the proposed RLS algorithm and compare the result in terms of separation distance between FSS earth station and 5G BS with and without RLS algorithm. The results confirmed that the RLS algorithm for adaptive beamforming makes the coexistence between 5G and FSS possible indicated by the significant reduction of separation distance between FSS earth station and 5G BS leading to the minimum interference of 5G BS to the FSS earth station.

Guiana space center general short and long term landscape

The Guiana Space Center CSG is moving towards evolution. Vega-C and Ariane 6 new launchers will be soon operated. Many facilities will be modified or created. One can highlight the adaptations of solid propellant plant as well as Vega launch pad and even more spectacularly, the building of new Ariane 6 launch pad called “ELA 4” with a design close to Soyuz one.Besides, the launch range also fits with these modifications. Especially, major expected changes must deal with the implementation of the Launch Base, satellite services, launcher localization improvements with the target of autonomous on board safety.These upgrades are driven by the Launch Base efficiency enhancement, by the necessary improvement of the ground and flight safety processes, and by the increasing issue of environmental protection. The main objectives are to obtain a more flexible, safe and secure, as well as environment friendly CSG.

Gender and the Digital Divide Across Urban Slums of New Delhi, India: Cross-Sectional Study.

BackgroundDisparities in access to specific technologies within gender groups have not been investigated. Slum settings provide an ideal population to investigate the contributing factors to these disparities.ObjectiveThis study aimed to examine gender differences in mobile phone ownership, internet access, and knowledge of SMS text messaging among males and females living in urban slum settings.MethodsA convenience sampling approach was used in sample selection from 675 unnotified slums. A total of 38 slum sites were then selected across four geographic zones. Of these, 10% of the households in each slum site was selected from each zone. One household member was interviewed based on their availability and fulfillment of the eligibility criteria. Eligible individuals included those aged 18 years and above, residing in these slums, and who provided voluntary consent to participate in the study. Individuals with mental or physical challenges were excluded from the study.ResultsOur results showed that females were half as likely to own mobile phones compared with males (odds ratio [OR] 0.53, 95% CI 0.37-0.76), less likely to have internet access (OR 0.79, 95% CI 0.56-1.11), or know how to send text messages (OR 0.93, 95% CI 0.66-1.31). The predictors of mobile phone ownership, internet access, and text messaging between males and females included age, individual education, housing type, and the number of earning members in a household in the adjusted analysis. Among males, the number of earning members was a predictor of both mobile phone ownership and text messaging, whereas household education was a predictor of both internet access and text messaging. Age and individual education only predicted internet access, whereas housing type only predicted text messaging. Among females, household education was a predictor of all the technology outcomes. Age and type of toilet facility only predicted mobile phone ownership; housing type only predicted internet access whereas television ownership with satellite service and smoking behavior only predicted text messaging.ConclusionsOur study findings showing disparate access to technology within gender groups lend support for further research to examine the causal mechanisms promoting these differences to proffer significant solutions. Specifically, our study findings suggest that improving household education is crucial to address the disparate access and usage of mobile phones, the internet, and text messaging among women in slum settings. This suggestion is due to the consistency in household educational level as a predictor across all these technology indicators. In addition, the mechanisms by which the number of household earning members influences the disparate access to technology among men call for further exploration.

Implementation of hybrid fractal metamaterial inspired frequency band reconfigurable multiband antenna for wireless applications

In the present paper authors propose the design and analysis of a hepta band metamaterial inspired octagonal shape antenna using hybrid fractals for wireless applications. Multiband characteristics in the designed antenna is accomplished by introducing of slotted octagonal shape radiating part with hybrid fractal form of Moore curve and Koch curve and two SRR cells. The frequency band reconfigurability is obtained with aid of PIN diodes placed inside the strips connected between Moore curve (fused with centered Koch curve) and feedline. During ON mode of PIN diode antenna operates at seven microwave frequency S-band WiMAX (3.4~3.69 GHz—IEEE 802.16e)/Lower C-band terrestrial fixed and mobile broadband application (4.25~4.76 GHz)/C-band WLAN (5.15~5.35/5.75~5.825 GHz—IEEE 802.11a] (5.4~5.9 GHz)/Lower X-band Earth exploration-satellite service ITU region 2 (7.9~8.4 GHz)/Upper X-band Amateur satellite operating band (10.45~10.50 GHz)/Lower Ku-band Radar communication application (13.25~13.75 GHz)/Middle Ku-band Geostationary satellite service (14.2~14.5 GHz) covering various wireless applications. Proposed design exhibit hexa/hepta band features during OFF/ON mode of PIN diode. An acceptable gain, stable radiation characteristics, and good impedance matching are observed at all the resonant frequencies of the proposed structure.

Design of a wideband right‐handed circularly polarized array of miniaturized mushroom‐shaped antennas for direct broadcast satellite application

AbstractIn this study, a wideband right‐handed circularly polarized (RHCP) array of microstrip patch antennas, for direct broadcast satellite (DBS, 12.2‐12.7 GHz) services have been presented. The single element of the array is a two‐dimensional mushroom‐shaped fractal antenna of resonating frequency 12.49 GHz and an impedance bandwidth of 1.12 GHz. The proposed single element is designed by etching a pair of Minkowski square boxes in one of the two opposite sides of a regular octagon. Furthermore, a thin slot of length equal to one side of the regular octagon is placed in‐between the two Minkowski boxes, which results in the proposed mushroom‐shaped radiating element. The proposed four‐element linear array resonates at 12.47 GHz and gives an impedance bandwidth of 1.04 GHz. The feed network of the array is designed in such a manner to make the array structure very compact. The fabricated single element gives an RHCP gain of 5.25 dBic and its corresponding circular Polarization (CP) bandwidth of 200 MHz. The array gives an RHCP gain of 11.59 dBic and a CP bandwidth of 460 MHz. The measured CP bandwidth of the fabricated array prototype ensures 92% coverage of the entire DBS band with circularly polarized wave, and hence can be used for its related applications.

Legal Aspects of Satellite Constellations

In recent years a few entrepreneurs proposed launching into space large fleets of satellites, consisting of hundreds of satellites, often referred to as ‘constellations’. Their role is to provide satellite services to the largest possible number of users on Earth. This article provides a review of key legal issues associated with satellite constellations, including responsibility and liability for potential damages caused by satellites being a part of a constellation, insurance, registration of space objects, allocation of radio frequencies and orbital slots, and space debris. satellite constellations, space law, space insurance, liability, space debris

Design and qualification of Ku-band-radiating chains for receive active array antennas of flexible telecommunication satellites

AbstractAirbus Italia recently developed enhanced passive components as key elements for its telecommunication Ku-band antenna product lines, tailored to reconfigurable payloads. This paper describes the design and qualification of a dual linear polarization Ku-band-radiating chain, developed for the DRA receive (Rx) active antennas embarked on the Eutelsat Quantum satellite. The feed chain covers the entire Ku-band frequency range allocated for fixed satellite services providing receive functionality and embedding sharp rejection features over the adjacent transmit band. The proposed design provides high radiation efficiency (>90%) and polarization purity (XPD > 33 dB), together with low RF losses and flat group-delay variation over a 13% fractional bandwidth, keeping a compact size and reduced axial length. The unit has been optimized for high reproducibility in high volume productions, typical of large DRA applications, for which stringent mass and dimensional constraints, as well as excellent amplitude and phase tracking among similar units, are key features. Details of the feed chain design and an overview of RF and environmental qualification test results are presented.

Proposal of spread spectrum MSK for BDS RDSS signal modulation

BPSK is the basis of current GNSS (Global Navigation Satellite System) signals. BDS (Beidou navigation satellite system) RDSS (Radio Determination Satellite Service) system also adopts BPSK to realize communication and ranging simultaneously. To realize higher system capacity, RDSS signals overlap in time and frequency domain. The signal performance is heavily determined by the MAI (Multiple Access Interference) between overlapping signals. In this paper, SSMSK (spread spectrum MSK) is proposed. The signal performance is investigated under four conditions considering the main lobe bandwidth and the receiver bandwidth. The maximum number of overlapping signals for SSMSK is 11.7% higher than BPSK when the receiver bandwidth is for the side subcarrier. And the value is 10.6% when the receiver bandwidth is. SSMSK can be received utilizing BPSK local signal. When the receiving bandwidth is 2 R c , the correlation peak of SSMSK_BPSK is identical to BPSK. The tracking accuracy of SSMSK is higher than BPSK when the correlation interval is between 0.2-1 chips. The accuracy of SSMSK_BPSK is higher than BPSK when the correlation interval is 0.5 chips. The disadvantage of SSMSK is larger quantization word length. SSMSK is a better modulation for RDSS based on the comprehensive performance.

Comprehensive analysis of compatibility between QZSS and GPS in Asia-Pacific region: Signal quality, RTK and PPP

The Japanese QZSS, with four operational satellites in orbit, provides positioning, navigation and timing services as a GPS-complementary system. However, the compatibility between GPS and QZSS has not been adequately investigated so far. In this paper, their compatibility, from the aspects of signal quality, GPS + QZSS inter-system RTK and GPS + QZSS combined PPP is comprehensively analyzed. First, the signal quality comparison using 10-day zero-baseline observations shows that although QZSS has slightly lower carrier‑to‑noise‑density ratio (C/N0) than GPS, it has GPS-comparable accuracies of 36.2 and 7.4 cm on L1 and L5 code observations respectively and 2.4, 2.1 and 2.2 mm on L1/L2, L1/L5 and L2/L5 geometry-free phase observations respectively, and an even better one of 22.3 cm on L2 code observation. Second, the short-baseline experiment testifies that GPS + QZSS inter-system double-difference (ISDD) RTK obtains better positioning performance than traditional double-difference (TDD) RTK in terms of ambiguity-fixing success rate (ASR) and positioning accuracy. This indicates a good compatibility between GPS and QZSS which benefits from their same frequency on L1, L2 and L5. And at 10° cut-off elevation, the GPS + QZSS with ISDD RTK model obtains the ASR improvements of 15.3%, 4.0% and 73.1% over GPS-only on L1, L2 and L5, respectively. The significant improvement on L5 is due to only 12 GPS Block IIF satellites transmitting the L5 signal. Third, the theoretical derivation demonstrates that the inter-system bias (ISB) in GPS + QZSS PPP is composed of the constant part (i.e., receiver-dependent hardware delay difference and AC-dependent clock datum difference) and the variable part. The analysis of ISB characteristics shows that ISBWUM and ISBCOM have the same variation trend and behave stably with a daily variation of 0.4 m, while ISBGBM makes a significant daily variation of 1.4 m. Furthermore, the GPS + QZSS dual- and triple-frequency PPP based on the observations of 40 GNSS stations in Asia-Pacific region show that the GPS + QZSS PPP performance using WUM and COM products is superior to that using GBM product. These results denote that WUM and COM products make GPS and QZSS more compatible in PPP. The four-satellite QZSS system is able to effectively improve the performance of RTK and PPP for GPS in Asia-Pacific region and this improvement increases with increasing cut-off elevation.

Complementary Sierpinski Knopp fractal antenna for emergency management system

AbstractIn this paper, the design and analysis of a complementary Sierpinski Knopp fractal antenna are presented. It is realized by applying the Sierpinski Knopp space-filling curve on the basic square monopole antenna. The performance metrics of the antenna such as S11 (reflection coefficient), voltage standing wave ratio, radiation pattern, gain and current distribution at resonant frequencies are analyzed by using ANSYS Electronic Desktop software package. FR4 dielectric material is used as a substrate in which the radiating element of an antenna is printed. Vector network analyzer and anechoic chamber are used for measuring the fabricated antenna in order to validate the simulated data. The proposed antenna resonates at three frequencies that are 2.08, 4.93, and 6.46 GHz with a reflection coefficient of −20.5, −23.1, and −24.3 dB, respectively. The suggested antenna covers the frequency bands for mobile satellite service, Public Protection and Disaster Relief communication devoted to the emergency management system and INSAT C band applications.