EMC TESTING: ANTENNA EVALUATION
Drones hone in on satellite antenna testing
Joakim Espeland of QuadSAT examines an alternative way to test ground based antennas S
atellite antenna testing is undergoing a revolution. Drone technology coupled with unique testing software could drastically change the way satellite antennas
are tested. This new approach means that antennas can be tested anywhere – easily and effectively, something that has until now been complex and costly.
IMPORTANCE OF ANTENNA TESTING To anyone involved in the testing industry, no matter the vertical, it is immediately apparent that testing is a critical part of any process. Satellite antennas are no exception and the impact of poor performing antennas is far-reaching. This is further impacted by the simple fact that space is getting more and more crowded, especially with the forthcoming launches in low Earth orbit (LEO). As we see more satellites launching in
LEO, the ground segment will be subject to different challenges and requirements which it is not at present able to deal with effectively. As opposed to Geosynchronous Earth Orbit (GEO) satellites that move with the Earth’s rotation, as a fixed point in
30 /// Testing & Test Houses /// March 2021
the sky, seen from earth, LEO satellites move at a very high speed in orbit much closer above the Earth. This means that they are not a fixed point in the sky and that antennas are constantly tracking and re-pointing to maintain connectivity. The ground infrastructure is, therefore, much more complex, and the potential for things to go wrong has increased. Naturally things do sometimes go wrong in orbit. When they do, often this could mean antennas pointing to the wrong satellites, causing satellite interference. It is widely reported that equipment failure is one of the biggest causes of interference, a problem that has caused massive challenges for the satellite industry for a number of years. There are a number of different types of interference, but the result of all of them is degradation, or in some cases, loss of service, sometimes even disrupting multiple services at one time.
CURRENT TESTING PRACTICES Currently, satellite antenna testing is carried out at large test ranges, often operated by academia or research institutions. There are a limited number of
test sites and these can be costly to use for some manufacturers as it can be logistically difficult, and these advanced facilities are expensive to construct. The facilities are often in demand and manufactures could risk that if their antenna is not just right, they can experience delays in the validation process and ultimately going to market. There are a number of different stages of testing, the first being antenna model validation and approval to connect to a satellite network. This is carried out prior to deployment and typically done with a satellite operator or the Global VSAT Forum. This stage means transporting them to the test range. When you consider the size of some of the satellite antennas, these are not something you can simply put in the mail. Many antennas operate in challenging
environments. In these scenarios, the antennas are often covered by radomes for protection. Even slight inaccuracies in radome manufacturing processes affect the performance of the antenna it covers. The size and shape of radomes complicate testing at current test ranges because they often do not fit onto the test-bench where
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