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

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

Apophis and the Waves - The need for Frequency Coordination and Radio Amateur and University Community Support Before, During, After Close Approach

On Earth most definitely and likely also around the Moon, in the few days centred on Friday, April 13th, 2029, 21:45 UT, every informed and curious naked eye, lens, mirror and dish within the horizon will be aimed at (99942) Apophis for an once-in-a-1000 years opportunity of scientific observations. Most will watch or listen. Many will transmit. Some will get in the way of others. And a few will blast it with all they can - for the best of science. We intend to start the discussion to include the public in the unique observation of Apophis, in particular focusing on the radio amateur community and the need for world-wide coordination to avoid mutual interference

More Bucks for the Bang: New Space Solutions, Impact Tourism and one Unique Science & Engineering Opportunity at T-6 Months and Counting

For now, the Planetary Defense Conference Exercise 2021's incoming fictitious(!) asteroid, 2021 PDC, seems headed for impact on October 20th, 2021, exactly 6 months after its discovery. Today (April 26th, 2021), the impact probability is 5%, in a steep rise from 1 in 2500 upon discovery six days ago. We all know how these things end. Or do we? Unless somebody kicked off another headline-grabbing media scare or wants to keep civil defense very idle very soon, chances are that it will hit (note: this is an exercise!). Taking stock, it is barely 6 months to impact, a steadily rising likelihood that it will actually happen, and a huge uncertainty of possible impact energies: First estimates range from 1.2 MtTNT to 13 GtTNT, and this is not even the worst-worst case: a 700 m diameter massive NiFe asteroid (covered by a thin veneer of Ryugu-black rubble to match size and brightness) would come in at 70 GtTNT. In down to Earth terms, this could be all between smashing fireworks over some remote area of the globe and a 7.5 km crater downtown somewhere. Considering the deliberate and sedate ways of development of interplanetary missions it seems we can only stand and stare until we know well enough where to tell people to pack up all that can be moved at all and save themselves. But then, it could just as well be a smaller bright rock. The best estimate is 120 m diameter from optical observation alone, by 13% standard albedo. NASA's upcoming DART mission to binary asteroid (65803) Didymos is designed to hit such a small target, its moonlet Dimorphos. The Deep Impact mission's impactor in 2005 successfully guided itself to the brightest spot on comet 9P/Tempel 1, a relatively small feature on the 6 km nucleus. And 'space' has changed: By the end of this decade, one satellite communication network plans to have launched over 11000 satellites at a pace of 60 per launch every other week. This level of series production is comparable in numbers to the most prolific commercial airliners. Launch vehicle production has not simply increased correspondingly - they can be reused, although in a trade for performance. Optical and radio astronomy as well as planetary radar have made great strides in the past decade, and so has the design and production capability for everyday 'high-tech' products. 60 years ago, spaceflight was invented from scratch within two years, and there are recent examples of fastpaced space projects as well as a drive towards 'responsive space'. It seems it is not quite yet time to abandon all hope. We present what could be done and what is too close to call once thinking is shoved out of the box by a clear and present danger, to show where a little more preparedness or routine would come in handy - or become decisive. And if we fail, let's stand and stare safely and well instrumented anywhere on Earth together in the greatest adventure of science

A novel evaluation method for in situ space debris detection based on conductive traces

o enable the detection of micrometeoroids and small-sized space debris (MMSD) in the sub-mm range, in situ detectors aboard a spacecraft are the tool of choice. Unfortunately, only a few projects have been sent to space until today. However, knowledge of the MMSD population is important to keep the reference models up-to-date and gain more insights into factors like the amount of debris and its distribution along certain orbits. This will be crucial for the safety of current and future spaceflight missions. Present-day in situ detection systems mostly rely on impact recognition and characterization using different methods. One of them is the perforation of a special detection area during such an event. These areas consist of one or more layers provided with conductive traces. Any interruption of one of these lines can be recognized using some kind of electrical continuity testing method or the determination of the resistance. This goes along with some drawbacks, like the difficult or even impossible multi-event recognition along one line. The proposed concept relies on a reflectometric approach. In doing so, for example, pulses are being sent along a well-defined transmission line, which is a part of the detection area. Any alteration in the characteristic line impedance, for instance, due to an impact, will generate reflections back into the generator. Their evaluation can provide the location as well as the complex impedance of the perturbation

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

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

Mobile Ground Station for CubeSat Operations

Operators of CubeSats often use Amateur Radio frequencies to get remote access to their small satellites. The frequency bands used are VHF (144-146 MHz), UHF (430-440 MHz) and sometimes also S-Band (2400-2450 MHz). For TT&C and data downlink a ground station is required, special attention has to be drawn on costs and regular maintenance. The lifetime of these antennas and ground station components is usually < 5 years and the service for the complete setup binds manpower. Furthermore, Central European locations for ground stations are not the best choice for LEO satellites on a sun synchronous orbit. This leads to 3-4 overpasses per day, 2 overpasses with a high elevation which results in longer contact time and closer distance. Other locations like Inuvik (CAN) provide more than 12 overpasses per day; northern regions are very interesting for long and more frequent communication times between earth and LEO Satellites. Therefore, the Institute of Space Systems (DLR) in Bremen is developing a remote controlled and mobile ground station for amateur radio frequencies, including antennas, servers and modern transceivers