Design and Evaluation of a High Bandwidth Patch Antenna Array for X Band Space Applications

The use of high frequency data transmission in space applications, e.g. in the X band, offers a variety of advantages compared to the frequently used S band transmission. Not only the antenna size and weight is dramatically reduced, which is a very crucial point in space applications, but also the possible bandwidth is increased. This paper describes the theo-retical properties and the design process for a stacked patch array antenna in the frequency range between 7 and 8.5 GHz. Another advantage of a broadband antenna is that it can be used “off-the-shelf” for a variety of different applications, even for those with smaller needs regarding bandwidth

Deployment verification of large CFRP helical high-gain antenna for AIS signals

Deployment verification of large CFRP helical high-gain antenna for AIS signal

Design and Evaluation of a High Bandwidth Patch Antenna Array for X Band Space Applications

The use of high frequency data transmission in space applications, e.g. in the X band, offers a variety of advantages compared to the frequently used S band transmission. Not only the antenna size and weight is dramatically reduced, which is a very crucial point in space applications, but also the possible bandwidth is increased. This paper describes the theoretical properties and the design process for a stacked patch array antenna in the frequency range between 7 and 8.5 GHz. Another advantage of a broadband antenna is that it can be used 'off-the-shelf' for a variety of different applications, even for those with smaller needs regarding bandwidt

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

L.A.R.S. - Mobile ground station for CubeSat operations

Many of the CubeSat and SmallSat operators in the academic field suffer from the fact that the ground station operations for Telemetry, Tracking and Control of their satellites is often quite challenging to maintain for the duration of a mission. The DLR Institute of Space Systems in Bremen, Germany, presents a remote controllable mobile ground station for CubeSat/SmallSat operations which completely fits inside a 20 ft shipping container. It operates in the VHF/UHF amateur radio frequency bands (144-146 MHz and 430-440 MHz) and is prepared for S band (2400-2450 MHz) using fully redundant state-of-the-art software-defined-radio transceivers. With the ground station presented in this paper, automated satellite operations with different satellites can be achieved. Tests with different SmallSats and CubeSats have demonstrated promising results of great performance with high sensitivity in reception, even at low elevations. Currently, the ground station is located for testing purposes at the Jade Weser Airport in Wilhelmshaven, Germany. In the near future it is planned to move the station to a northern location to achieve optimal contact opportunities to connect and remain in contact for longer durations in polar satellite orbits

Design and Evaluation of a Spiral Antenna for X-Band Space Applications.

Abstract—The use of high frequency data transmission in space applications, e.g. in the X band, offers a variety of ad-vantages compared to the frequently used S band transmission. Not only the antenna size and weight is dramatically reduced, which is a very crucial point in space applications, but also the possible bandwidth is increased. This paper describes the theo-retical properties and the design process for a spiral antenna and the corresponding balun in the frequency range between 8 and 12 GHz

A SELF-DEPLOYING AND SELF-STABILIZING HELICAL ANTENNA FOR SMALL SATELLITES

Space antennas with a helical geometry are an advantageous choice for many applications, for instance if the transmission of electromagnetic waves with a circular polarization is intended, or if signals from terrestrial objects shall be received with a high angular resolution. In all these cases the desired electromagnetic properties of a helical geometry can be combined with the mechanical advantage that the antenna acts as a compression spring, provided that its core structure has the necessary high spring stiffness but can nevertheless easily be compressed. Such an antenna has been developed by DLR Institutes in Bremen and Braunschweig together with some industrial partners for a small satellite named AISat which shall be able to pursue the position of individual ships in critical sea areas in order to improve the security of seafare trade. The development was very challenging since the antenna must expand from a stowed stack length of only 10 centimeters to a total length of 4 meters. Only a special carbonfiber core under the conductive coating and a system of stabilizing cords led to a satisfying solution. Both the self-deployment and the self-stabilization function of this innovative antenna concept have been successfully tested and verified under zero-g-conditions in the course of a parabolic flight campaign. It could be convincingly demonstrated that the helical antenna can really achieve its desired contour in weightlessness within some seconds and maintain the required stability. Beyond the current application for the AISat satellite it is therefore a quite promising concept for future satellites

Detektion von Funksignalen im internationalen Schiffsverkehr

Aufgrund der stetig steigenden Verkehrsdichte im Schiffsverkehr nehmen auch die Anforderungen an die Überwachung von Gewässern zur Verkehrssicherung und zum Schutz der maritimen Umwelt zu. Die aktuellen Verkehrsüberwachungssysteme nutzen neben den vorhandenen Systemen wie Radar, Wetter- und Wasserstands-sensoren zusätzlich das automatische Schiffsidentifizierungssystem (AIS). Die Überwachung des Seeverkehrs erfolgt in küstennahen und besiedelten Bereichen meist durch ein gut ausgebautes Netz von AIS-Bodenstationen entlang der Küste. Außerhalb dieser Bereiche ist oft nur eine lückenhafte Beobachtung möglich und auch der Empfang von Satelliten AIS befinden sich derzeit noch in der Aufbauphase. In diesem Beitrag wird das DLR Projekt AISat vorgestellt. Dieses satellitengestützte Projekt trägt zur Entwicklung von Techniken im Hinblick auf den Empfang von Funksignals zur globalen Überwachung des Schiffsverkehrs bei

Development, Testing and In-Orbit Verification of a Large CFRP Helical Antenna on the AISat Mission

A design for a 4 m long, ultra-light, high-gain, helical Antenna made from fiber-composite material will be presented. The antenna was designed for the DLR NanoSatellite Mission AISat to receive signals from the Automatic Identification System (AIS) of maritime applications. A description of the antenna deployment strategy including release mechanisms will be given. The proof of concept will be presented based on experimental results gained during the 15. DLR parabolic flight campaign (PFC) in March 2010 and several development tests. Finally, in-orbit demonstration was performed during the two years of operation of the AISat after the successful launch on June 30, 2014 from Sriharikota (India). The AISat satellite was developed at the DLR Institute of Space Systems aiming at the worldwide receiving of AIS signals. These signals can usually be received along coast lines or from ship to ship in range of sight. They provide identity, position, velocity and heading and are therefore used for ship tracking. A number of AIS satellites already exist but especially in areas with high ship traffic density identification problems arose due to the high signal density. Therefore AISat has a distinctive ultra-light, high-gain, helical antenna which allows to focus on comparably small areas on the Earth surface. IT thus shall enable the receiving of Class A and B and SART signals especially in high traffic density zones. The antenna is a 4 m long and 0.57 m in diameter deployable helix antenna made from fiber composite material, which can be stowed in a very flat volume of merely 100 mm height. The wire of the antenna is made from carbon fiber material with a diameter of 8 mm. It is covered with a copper cord for high electrical conductivity. Based on its design with 8 windings the total length of the wire itself is approx. 16 m. Through the dedicated usage of fiber composite materials this wire weighs less than 1 kg including the copper cord. In stowed configuration, in which it is held down by 3 release mechanisms, the antenna has stored elastic energy like in a spiral spring. After release the structure deploys autonomously in orbit to a length of 4 m. When deployed, the antenna is still pre-stressed using control cords in order to increase its bending stiffness

DEVELOPMENT AND IN-ORBIT VERIFICATION OF LARGE CFRP HELICAL HIGHGAIN ANTENNA ON THE AISAT MISSION

A deployment strategy for a 4 m long, ultra-light, high-gain, helical Antenna made from fiber-composite material will be presented. The antenna was designed to fly on the DLR NanoSatellite AISat for the receiving of signals from the Automatic Information System (AIS) for maritime applications. A description of the antenna deployment strategy including release mechanisms will be given. The proof of concept will be presented based on experimental results gained during the 15. DLR parabolic flight campaign (PFC) in March 2010. Aim of this campaign was to verify the antennas’ and the release mechanisms’ performance in weightlessness for the following space mission. Tests with gravity compensation devices in a laboratory are not well suited due to the very complex deployment behaviour like coupled dynamic longitudinal and torsion motions. Final, in-orbit demonstration was performed during the two years of operation after the successful launch of the DLR satellite AISat June 30, 2014 from Shriharikota (India). The AISat was developed at DLR Institute of Space Systems aiming at the worldwide receiving of AIS signals from ships. These signals can usually be received along coast lines or from ship to ship in eyeshot distance. They provide identity, position, velocity and heading of ships and are therefore used for ship tracking. A number of AI-satellites already exist but especially in areas with high ship fluctuation identification problems arose due to the high signal density. Therefore AISat has a distinctive ultra-light, high-gain, helical antenna which allows to focus on comparably small areas and thus enables a receiving of Class A and B and SART signals. The antenna is a 4 m long and 0.57 m in diameter deployable helix antenna made from fiber composite material, which can be stowed in a very flat volume with a height of 100 mm. The wire of the antenna is made from carbon fiber material with a diameter of 8 mm. It is covered with a copper cord for high electrical conductivity. Based on its design with 8 windings the total length of the wire itself is approx. 16 m. Through the dedicated usage of fiber composite materials this wire weighs less than 1 kg including the copper cord. In stowed configuration, held down by 3 release mechanisms, the antenna has stored elastic energy like in a spiral spring. After releasing the structure it deploys autonomously in orbit to a length of 4 m. When deployed, the antenna is still prestressed by means of control cords to increase its bending stiffness. During the 15. DLR PFC the deployment of the helix structure was verified. Four structures with different materials and different wire diameters for differing stiffness properties were tested. Additionally the prestressing of the most promising structure was altered. The deployment behaviour was video taped and reaction forces were recorded. This is a basis for further deployment predictions with changing designs and for reaction force predictions acting on the satellite for guidance and navigation control. The contribution will be concluded with a summary of the data received and lessons learned during the two years of operation of the AISat from 2014 to 2016