Communications satellite technology
What is the laboratory’s role?
Without radio waves, (almost) nothing works
The race for the best positions in near-Earth orbits, known as Low Earth Orbits (LEOs), is in full swing. More and more unmanned aerial vehicles are taking to the skies. Antennas play a key role in this – if, for example, communication with a satellite is lost, it is lost forever.
Communication between so-called ground stations (ranging from huge gateways to a smartphone) and the satellites relies on the support of ever-new, ever-more-sensitive and flexibly adaptable smart antennas.
In the Communications Satellite Technology Laboratory, the key characteristics of antennas are determined through calculation and measurement. Among the most important characteristics are gain – that is, how strongly and effectively an antenna can concentrate a transmitted signal – and what is known as the directional pattern. This indicates how precisely and to what standard an antenna transmits signals to its receiving points without interfering with other radio systems. Polarisation characteristics – that is, the spatial orientation of the electric or magnetic field of the waves emitted by the antenna – are also important for determining an antenna’s characteristics.
Among the tests we carry out on all types of antennas in the Communications Satellite Technology Laboratory is a test to check whether they comply with specified standards. Standards set by the European Telecommunications Standards Institute (ETSI), the European Space Operations Centre (ESOC) and, above all, the International Telecommunications Union (ITU) ensure that the increasing volume of data transmitted over the air does not interfere with one another. Only strict adherence to these standards guarantees that signals reach their intended recipients without wasting too much of the scarce frequency spectrum.
Opportunities for students
Getting stuck in with antenna construction
In the laboratory, students can learn about and gain hands-on experience in measuring critical parameters such as equivalent isotropically radiated power (EIRP), gain-over-noise-temperature (G/T) and the bit error rate of active transmit-receive systems.
We carry out electronic measurements of steerable antennas and analyse the tracking characteristics of active array antennas. We are also able to determine bi- and monostatic radar cross-sections.
Thanks to its capabilities, the Laboratory for Communications Satellite Technology at Hochschule München ranks amongst the very few such facilities worldwide and carries out numerous exciting research projects for various partners across the globe.
Laboratory facilities
World-class antenna test chamber
At the heart of the Communications Satellite Technology Laboratory is a Compensated Compact Range (CCR, link), an antenna measurement chamber designed to generate a plane wave field within a relatively small space. To produce a comparable wave field outdoors, a distance of several kilometres between the transmitting and receiving antennas would be required. The measurement chamber effectively simulates a much greater distance between the transmitting and receiving units. This artificially created distance is necessary in order to measure antennas precisely.
The chamber consists of a five-axis antenna rotation stand with a positioning accuracy of 1/1000 of a degree. This is housed in a chamber lined with absorbers, in which any electromagnetic waves that might interfere with the measurements are absorbed. Remote-controlled cameras allow the antennas under test to be observed from the control room whilst measurements are being taken.
The accuracy that can be achieved in the university’s CCR when taking measurements in the frequency range from 800 MHz to 110 GHz is on a par with, or even exceeds, that of a very small number of such measurement chambers worldwide. Research into improving such chambers is also part of the collaborative work carried out by the Laboratory for Communications Satellite Technology.
The laboratory is currently able to use signal sources up to 110 GHz and is equipped with network analysers featuring eight receivers operating up to 67 GHz.
Laboratory projects
Detection of aircraft and surface properties
Students and research staff members have a wide range of opportunities to get involved in exciting research projects as part of their bachelor's degree, master's degree and PhD theses.
Among the projects undertaken to date, one that stands out is the design, development and subsequent testing of a so-called frequency-selective plate. This plate enables data rates to be multiplied during the transmission of signals, for example from geostationary communications satellites. The trick behind the frequency-selective panel is that, depending on the frequency, it allows some of the signals to pass through whilst reflecting others. We developed such a panel in the laboratory in collaboration with Airbus. The prototype we developed can multiply the capacity of, for example, geostationary satellites with very little effort.
A phase-controlled array antenna has been developed for mobile terrestrial platforms which is capable of focusing on moving targets without the need for mechanical tracking.
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A newly developed radar measurement method can be used to determine not only the distance, relative velocity and radar cross-section, but also the reactive properties of surfaces. This makes it possible to analyse whether the surface is made of metal or another material. This project involved providing support for the development of a foldable parabolic reflector for the company HPS.
Our partners in such research and development projects include the European Space Agency (ESA), the Technical University of Munich (TUM) and many major companies in the telecommunications and satellite communications sectors, including Infineon, Brazilian Telecom, Sky Mexico, Airbus and IABG. Specialist manufacturers of medium-sized enterprises, such as HPS Munich, FSA Munich, MIRAD (Switzerland) and Zinwell (Taiwan), are also among our project partners.
The Laboratory for Communications Satellite Communication and the CCR offer interested students the opportunity to gain an insight into the development of cutting-edge technology whilst still studying – and to get involved in it themselves.
Contact
The laboratory is located in Building E at 98b Dachauer Straße, E0117a.
If you have any ideas or enquiries, please feel free to contact the head of the laboratory, Professor Georg Strauß, at any time.