A Compact Single-Layer Dual-Band Microstrip Antenna for Satellite Applications

In this letter, a compact single-layer, single-feed, dual-frequency microstrip antenna with a high frequency ratio is proposed. This antenna has a broadside and symmetrical radiation patterns suitable for space-borne applications. The prototype was fabricated on a Rogers RT/duroid 5880 substrate with a relative permittivity of 2.2 and thickness of 1.58 mm. The dual-band behavior is achieved by a shorting pin at 1.7–1.706 and 8.011–8.277 GHz with the frequency ratio of 4.75. In addition, the antenna is miniaturized by 46% compared to the conventional rectangular patch.

Antennas for CubeSat Communication

Miroslav Veljovic

CubeSats are a type of small satellites (< 500 kg) that weigh several kilograms and consist of multiple Units (U) measuring 100 × 100 × 113.5 mm3. CubeSats emerged as a low-cost alternative to conventional large satellites, and have since demonstrated capabilities for communication, Earth observation, technology demonstration and many other. The primary goal of CubeSats, as it is the case with any miniaturized satellite, is to reduce the cost of orbital deployment. CubeSats are commonly launched as a secondary payload on large launch vehicles. One or several satellites are placed in a dedicated deployment system, which typically accommodates three CubeSat Units. The deployment system strictly limits the dimensions of any features on the CubeSat surface. CubeSat antennas perform the same functions as antennas on conventional satellites, such as telemetry and command, communication, navigation or inter-satellite links (ISL). However, most traditional antennas for small satellites are not suitable for CubeSats due to the profile constraints of the deployment system. Two approaches for antenna design are generally adopted. In the first, one or several low-profile antennas are placed on the CubeSat exterior. In the second, deployable antenna structures are used if the CubeSat platform does not offer sufficient dimensions. At low frequencies, the additional space is required to achieve a good radiation efficiency, whereas at high frequencies an increased antenna aperture provides a high gain. This thesis describes several antenna geometries, both low-profile and deployable, which enable several communication aspects of an Internet-of-Things (IoT) constellation of 3U CubeSats in the Low Earth Orbit (LEO). The main novelty of the proposed solutions is in their electromagnetic performance, as opposed to most CubeSat antenna designs where the mechanical design is the main achievement. The presented antennas succeed to exhibit a wide bandwidth or a specified radiation under strict size constraints. The thesis presents several wideband aperture-coupled patch antennas for TT&C and data downlink in S and X bands. A thoroughly investigated shielded-stripline feeding structure enables a wideband circular polarization (CP) with a unidirectional radiation, and demonstrates capabilities such as interference suppression of adjacent frequencies and efficient CubeSat integration. Patch-antenna arrays in L band are then presented, which radiate several independent beams for the capacity increase of an IoT machine-to-machine (M2M) communication system. The high permittivity of the antenna substrates lead to a strong coupling to the 3U CubeSat structure, emphasizing the importance of the antenna placement. Finally, different configurations of high-gain fixed-beam reflectarrays (RA) and transmitarrays (TA) are for the first time proposed for CubeSat ISL LEO communications in K band. Two novel unit cells are presented for RA and TA antennas, based on coupled loops and aperture-coupled patches, respectively. An axially corrugated CP horn antenna is designed as the feeding element for the arrays. A prototype of this antenna is fabricated using additive manufacturing in aluminum. The performance of all antennas, presented in this thesis, is validated by agreements between the calculation and 3D-simulation results and the VNA and anechoic-chamber measurements of several prototypes.

EPFL2020

PDMS, A Robust Casing for Flexible W-BAN Antennas [EurAAP Corner]

Anja Skrivervik Favre, Jovanche Trajkovikj, Jean-François Zürcher

This paper describes a new technology for the realization of soft, flexible, and robust antennas intended to operate in a harsh environment. One of the main characteristics of the proposed technology is the ease of fabricating antennas in a simple lab environment. The method is based on the use of a silicon-based elastomer, polydimethylsiloxane (PDMS), for the substrate material, and copper meshes or any kind of perforated metal plates as flexible conductive materials. The initial liquid state of the PDMS allows a lot of freedom in the fabrication process, both from the electrical and mechanical points of view. The electrical and mechanical properties of the substrate can be adjusted by loading the PDMS with inclusions having low or high permittivity and/or density, thus controlling the permittivity and the rigidity. Another good characteristic of the initial low viscosity of PDMS is the possibility of shaping the antennas and substrates in in-house fabricated moulds. Copper meshes or perforated metal structures enable good adhesion between the substrate and 288 IEEE Antennas and Propagation Magazine, Vol. 55, No. 5, October 2013 conductor, and improve the overall flexibility. Measured results showed good repeatability of the substrate samples, both with or without inclusions. To demonstrate the versatility of the proposed technique, several antenna prototypes were built and characterized. All the antennas were flexible and showed good radiation characteristics. The antennas were exposed to tests such as washing and bending, in order to assess their robustness to environmental changes. © 2014 IEEE.

Institute of Electrical and Electronics Engineers2013

A simple & [and] accessible front-end satellite receiver for communications and e-learning in emerging countries

Olivier Videme Bossou

For the universities of the emergent countries, and those of Cameroon in particular, the fight to reach a durable development requires to know the needed scientific and technical information for their development, how to get it and to spread it out among partners in the country. Obviously, the complete answer to these preoccupations lies well beyond the framework of this project, but a projection, partial but highly significant, can nevertheless be obtained if one concentrates one's efforts on a specific technological field : in the present study, we shall treat of antennas for telecommunications systems. This subject is highly suitable as example and potential incubator for future achievements. The ultimate goal is to design and carry out the fabrication of a system of satellite communications adapted to the financial resources and to the development needs of the universities of the South. First of all, we will review the state of the art in satellite communication systems, both for already operating ones and also for new systems, still under development. Then we will determine which system of satellite telecommunications has a receiver and communication fees with affordable costs : our choice will be made on Worldspace satellite system, which was actually designed for developing countries. We will also review the status of planar antenna and low noise amplifier technology, and then explicit the basic challenge involved in our thesis project. One of the aims of this project is to use local wood as dielectric in SSFIP type antennas. Before using a material as dielectric in an antenna design, it must be characterized. Before carrying the characterization of local wood species, we will begin by reviewing some commonly used dielectric measurement techniques. Then we will carry out a series of measurements to characterize the species of wood growing in the Cameroonian forest. At the end of the series of measurements and according to the dielectric losses observed, we will select the species of wood best suited to make a good substrate for a microstrip antenna. Next, we will design, manufacture and test low cost antennas. These antennas must satisfy not only technical criteria compatible with those of the telecommunications system chosen but, even most importantly, it must meet socioeconomic criteria : the antennas must be manufactured with low cost and locally available materials, making use of simple technological processes. Once we have found the wood species that exhibits the lowest dielectric losses, we will simulate, and then manufacture the SSFIP type antenna with wood as substrate and aluminium as conducting element. Then we will measure its characteristics and check whether they are compatible with those of a Worldspace receiver. The signal received from the satellite by the antenna is very weak. It will be important to strengthen the received signal with a low noise amplifier (LNA) before connecting the antenna to the receiver. Thus the antenna and the LNA constitute an active antenna and form what we call here the radiofrequency (RF) front-end. We will design, manufacture and measure the LNA characteristics. A simple manufacturing process must be used to realize these antennas, because later on they must be manufactured locally in Cameroon : this is a determining challenge to ensure the economic independence, which is essential in our thesis project. Afterwards we will join the LNA to the planar antenna and connect the active antenna obtained in this manner to a commercial Worldspace receiver. Finally, we will perform receiving tests of the Worldspace radio station with the system designed. In parallel, our project includes a second goal, which presents an equivalent significance. We will use existing Matlab codes to develop an online course to teach antenna theory. In addition, at the end of the project and when the Cameroonian local manufacture would have started, we will put all algorithms used for the antenna design on the web site in a multi-media applet, together with a complete documentation of all the manufacturing technologies used. The courses that already exist in Lausanne and Yaounde, relating to the description of other types of antennas will be added, thus leading to a complete teachware that would ensure the durability and the dissemination of the results obtained, and would provide an invaluable tool for teaching and training.