Antennas for small satellites

Second generation disaster-monitoring microsatellite platform

This paper has two objectives: to discuss the role of small satellites in the satellite communications R&D (research and development) in the IT (Information Technology) era, and to show communications technology topics in small satellite applications. The need for small satellite communications is first discussed. The future (next three decades) vision of satellite communications R&D is then described, corresponding to the recent rapid increase of capacity of terrestrial links. Third, the role of small satellites in future satellite communications R&D is discussed. Finally, small satellite related communications technology topics are described to show that there are many interesting research issues.

"Sweeting, Prof. Sir Martin (Nicholas), (born 12 March 1951), Professor of Satellite Engineering, since 1990, Distinguished Professor, since 2006, Chairman, Surrey Space Centre (formerly Centre for Satellite Engineering Research), since 2015 (Director, 1996–2014) and Director, National Hub on Future Artificial Intelligence and Robotics for Space, since 2019, University of Surrey; Founder and Executive Chairman, Surrey Satellite Technology Ltd, since 2008" published on by Oxford University Press.

A microstrip second-iteration square Koch dipole fractal antenna is presented. This meandered antenna has a total length of 56.56 cm including its feed gap and was printed on the diagonal of a 100 mm × 100 mm PCB card that acts as CubeSat face. The antenna that was designed to optimize space shows acceptable performance at its resonance frequency of 455 MHz within the 70-centimeter band, a band that is commonly used for TTC CubeSat subsystems. The designed fractal antenna shows a reflection coefficient below −20 dB, a VSWR below 1.2, a −10 dB bandwidth of 50 MHz, and impedance magnitude of 56 Ω, while the average maximum gain around its resonance frequency is 2.14 dBi. All these parameters make this designed antenna suitable for small satellite applications at a band where a linear λ/2 dipolar antenna working at 455 MHz would be about 32.97 cm long, which does not fit within the largest dimension of a CubeSat face corresponding to 14.14 cm.

A small director array (SDA) is an antenna gain enhancing section of the low-profile smart antenna which can be used as a fixed array or reconfigurable array using switched parasitic elements. Gain improvements up to +10 dBi are achieved in the SDA through a Yagi-Uda configuration using parasitic elements with a large diameter. The array height is reduced by 50% comparing with the standard Yagi-Uda antenna. The reconfigurable SDA used an electronically steerable switched parasitic arrangement so that the beam can be steered from 0° to 360° in the horizontal plane. The height of the reconfigurable SDA is 0.2 λ. The measurements proved that the reconfigurable SDA can increase the antenna gain by 3 dB. The front to back ratio showed significant improvement. The proposed SDA also had the advantages of low cost and low power consumption, thus promising for applications in small satellites, unmanned aerial vehicles and mobile terminals.

Harris is currently developing different types of imaging hyperspectral instruments for CubeSat and other small satellite applications. All of these instruments utilize Fourier Transform Spectrometer (FTS) interferometer technology, which has been proven on larger space instruments for NASA and NOAA. Most of these instruments are aimed at remote sensing of the earth from low orbit. One example is HyperCube™, which is a hyperspectral mid-wave infrared (MWIR) instrument compatible with 6U CubeSats capable of collecting vertical moisture profiles and three-dimensional winds in the earth’s atmosphere. Another example is Harris’ HyperStare, which is a larger-aperture imaging FTS instrument that provides improved sensitivity and spatial resolution for detection of trace greenhouse gases in the atmosphere. This paper will provide design summaries and performance capabilities of each of these new instrument types. It will also discuss Harris’ newly developed ground station capability for operating small constellations of small satellites. In addition, new FTS technologies that may be suitable for future small satellites will be discussed.

Proximity operations about and identification of non-cooperative resident space objects using stereo imaging

Separated turnstile Antenna can provide saddle-shaped and hemispherical patterns. Its ability in making the arbitrary earth covering pattern has provided a lot of applications in small LEO satellites. In this article, the proper pattern for separated turnstile antenna which is mounted on a small LEO satellite, is synthesized and shaped. Wired model of separated turnstile antenna is analyzed by Moment Method and its gain pattern, polarization and input impedance are calculated. Ability of dual band operation of this antenna has been investigated in the paper and a dual band separated turnstile antenna bas been designed for the satellite. Also, Effects of antenna geometrical parameters on its pattern have been researched and calculated in the paper.

The current emphasis in the satellite industry is on replacing large satellite platforms with one or more smaller satellites, built at lower costs, yet able to accomplish similar mission objectives. In this context, there is increasing interest in the potential capabilities and applications of so-called -satellites of 10-100 kg. However it is recognized that such small satellites pose severe constraints on payload volume, mass and power. Thus, they would appear to be inappropriate for missions such as synthetic aperture radar (SAR) imaging, where payloads have significant size and power demands - specifically the large SAR antenna and high-power radar transmitter. The primary reason for the high transmit power requirement is that traditional SAR systems use backscatter, which is weak from most terrain types as most energy is scattered in the forward direction. Thus, if it were possible to gather this forward scattered element, then the transmit power requirements could drop significantly, potentially making it feasible for installation on a micro-satellite. This research is based on this principle of collecting to the forward scattered element -a novel method by which two micro-satellites fly in a specific formation to accomplish a SAR imaging mission bi-statically. The transmitting satellite will be the master, with the receiver satellite slaved off it for synchronization. The satellites view a swath of 30x30 km, at a ground resolution of 30 m, from an altitude of 700 km. The constellation geometry proposed requires minimal orbit control resources, and allows for the resolution of the left-right ambiguity. The satellite design is based on the Surrey Satellite Technology, Ltd. enhanced microsatellite, with a mass of 100 kg, and a standard volume of 1x1m base and a 0.6 m height. The satellite shape will be a truncated pyramid, allowing for increased power production by the body-mounted Gallium Arsenide solar cells and provides a larger platform base for the 2.5 m diameter parabolic dish antenna. The signal is transmitted at 2.4 GHz, as a chirped pulse of 34 mus duration. The receiver will collect, compress and store the data, which will later be sent to a ground station. This will require a data storage of 1 Gbit and a downlink of 2 Mbps. The main processing of the SAR data will be conducted on a ground facility, due to the complex and time required for processing.

The potential of small satellites has frequently been likened to the advent of the personal computer. The drive towards smaller space systems has unquestionably opened the doors to space for dozens of companies and countries. Indeed, the “faster, better, cheaper” mentality embraced by small satellite producers became an industry mantra. However, nano-, micro-, and mini-spacecraft remain a very small part of the overall space industry landscape. This paper examines an industry view of the potential of small spacecraft to create a PC-style revolution in the satellite industry.Increases in the size of the small satellite market can come in two ways. Either small spacecraft will supplant larger ones in existing markets or they will create large new markets. To evaluate current and future small satellite penetration into the existing satellite market, the market is segmented into a matrix of three basic satellite types: LEO, GEO, and interplanetary, and four applications: communications, remote sensing, science, and weather. Although small satellites have made important strides, they do not dominate any of the identified market segments. Furthermore, small satellites suffer from fundamental weaknesses that are unlikely to be overcome by medium-term advances in small satellite technology.If existing markets will not provide sizeable growth then the only remaining possibility is the creation of new markets. Historically, the market potential of most revolutionary advances does not come from the replacement of old technology but from the generation of entirely new products and services enabled by this new technology. The catalyst for this transformation is typically one new capability that itself warrants adoption of the new technology.Advances in small satellite technologies will support modest advancements of the small satellite industry, but it is considered unlikely that they will cause any major shifts in the space industry in the near- to medium-term.KeywordsInternational Space StationSmall SatelliteScience MissionLarge SatelliteSmall SpacecraftThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

In this paper, a high efficiency broadband planar array antenna is developed at X-band for synthetic aperture radar (SAR) on small satellites. The antenna is based on a multi-layer element structure consisting of two dielectric substrates made of Taconic TLY-5 and three copper layers (i.e., the parasitic patch (top layer), the active patch (middle layer), and the ground plane (bottom layer)). The parasitic patch resides on the bottom surface of the upper TLY-5 substrate while the active patch is printed on the top surface of the lower substrate. A Rohacell foam material is sandwiched between the top layer and the middle layer to separate the two dielectric substrates in order to achieve high directivity, wideband, and to keep the antenna weight to a minimum as required by the SAR satellite application. To satisfy the required size of the antenna panel for the small SAR satellite, an asymmetric corporate feeding network (CFN) is designed to feed a 12 × 16 planar array antenna. However, it was determined that the first corporate feed junction at the center of the CFN, where higher amplitudes of the input signal are located, contributes significantly to the leaky wave emission, which degrades the radiation efficiency and increases the sidelobe level. Thus, a suspended microstrip slab, which is simply a wide and long microstrip line, is designed and positioned on the top layer directly above that feed junction to prevent the leaky waves from radiating. The experimental results of the antenna show good agreement with the simulated ones, achieving an impedance bandwidth of 12.4% from 9.01 to 10.20 GHz and a high gain above 28 dBi. The antenna efficiency estimated from the gain and directivity eclipses 51.34%.

Precise real-time navigation of the small TJU-1 satellite using GPS, GLONASS and BDS

In this paper, an S-band three-dimensional antenna for small satellite application has been presented. Folding the radiating element, use of shorting wall and ground reflector etc. different optimization techniques have been obtained to achieve a desirable performance from the antenna. Finally, the proposed antenna successfully obtained operating bands at 2–2.27 GHz and 2.53–3.58 GHz. The peak gain of the antenna is up to 4dB. The simple design structure make the antenna easily fabricable for mass production from a single copper sheet using stamping metal sheet method or 3D printing technology. The design and analysis of the antenna have been performed using electromagnetic simulation software. S band operation, directional radiation property, up to 4dB realized gain over the operating frequency make the antenna a candidate to be applied for communication system in small satellites.

This paper presents a flat-panel dual-band transmitarray antenna (TA) with linear polarization designed for concurrent uplink (29 GHz) and downlink (19 GHz) satellite communications. The TA features a low-profile and lightweight microstrip aperture (103.4 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 103.4$ </tex-math></inline-formula> mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 1.7$ </tex-math></inline-formula> mm), coupled with a commercial-off-the-shelf horn antenna for excitation. Our novel TA element is carefully designed to achieve high-efficiency transmission and independent phase control in both operating bands, while ensuring that its features can be fabricated using standard PCB manufacturing techniques. Additionally, by arranging the phase tuning mechanism for each band on opposite sides of the aperture, space is created to accommodate DC biasing circuitry for electronic beam scanning applications in future iterations of the design. A passive prototype of the TA was fabricated using conventional PCB and additive manufacturing techniques. The TA’s performance was validated with measurements that demonstrated high gain (22.9 dBi and 20.2 dBi), aperture efficiency (15.4% and 19.3%), and 1-dB gain bandwidth (4.3% and 13.4%) in the respective operating bands (29 and 19 GHz). With its cost-effectiveness, lightweight design, and rapid deployment capability, the proposed TA offers an efficient solution for establishing wireless communications in remote locations, making it ideal for tactical, work-site, and small satellite applications.

A new constellation comprising of eight microwave small satellites is proposed in this study. This constellation is capable of covering the entire globe every two hours. With six more satellites added and properly arranged, a constellation is able to provide hourly observations of fast-evolving severe weather systems like hurricanes. Compared to current polar-orbiting satellite which normally carries one passive microwave instrument onboard, a small satellite constellation is more cost-effective, requires a shorter development cycle and has smaller failure impact. NOAA Center for Satellite Applications and Research (STAR) has built a full radiance transformation system (ARTS) that is applicable for small satellite calibration, validation and data processing. Hourly NWP forecast fields for tropical storm Debby (2012) will be produced and used as inputs to Community Radiative Transfer Model (CRTM) to simulate the designed microwave small satellite observations to demonstrate their values for monitoring and predicting hurricane and typhoon events.