26 September 2025
Collaboration with Swedavia for increased flight safety
Researchers in Electronics Systems, together with Swedavia, have tested radar altimeter antennas in order to understand how they interact with upcoming 5G systems. The mission was to characterize the antennas’ ability to capture the correct signals and to estimate the risk that signals from, for example, 5G could interfere with the signals desired for the aircraft.
This time, the focus was on the reception angles of the radar altimeter antennas, to see how much unwanted signal is picked up from the sides compared to the desired signals in the aircraft’s longitudinal direction. Since this type of measurement is very challenging to perform outdoors on an aircraft, the antenna’s surrounding environment is instead recreated in a laboratory.
“We have built up knowledge, equipment, and collaborations over many years. This allows us today to contribute with research that directly strengthens flight safety and develops the aviation technology of the future,” says Jonny Johansson, Professor in Electronics Systems.
When the aircraft is in the final phase of landing, the radar altimeter is used. The radar altimeter sends out radio waves (red waves) that bounce off the runway; the travel time determines the altitude. Signals from, for example, 5G masts (blue-green) or phones (black) located at the side of the runway risk interfering with the radar altimeter’s signals. We have measured how sensitive the radar altimeter’s antenna is to signals from different angles.
Knowledge, expertise, and years of experience go a long way, but the Electromagnetic Compatibility (EMC) Laboratory also plays a major role in research that improves flight safety. The EMC Laboratory is the only one of its kind at a Swedish university and enables this type of advanced measurement. The lab features a fully anechoic chamber, for the frequency range 30 MHz – 18 GHz, where all walls, floors, and ceilings are covered with electromagnetic absorbing material. Technically, in antenna measurements, a fully anechoic chamber resembles free space.
“It is our EMC lab and the collaboration with Swedavia that make these measurements possible, and that is something we are very proud of,” says Jonny Johansson.
Through long-term collaboration with Swedavia, unique equipment, and cutting-edge expertise, researchers in Electronics Systems have established themselves as an important resource for measurements and analyses in airport environments. Among other things, they have carried out measurements at Kallax Airport in Luleå and explored opportunities to create a test environment to support green aviation at Skellefteå Airport.
“Together we are strong! Luleå University of Technology contributes highly skilled researchers in electromagnetic compatibility, and Swedavia contributes experts in flight operational systems,” says Pär Weilow at Swedavia’s EMC and Radio Spectrum Management unit.
The measurement results show that the antennas generally performed as expected. For example, radar altimeters, which help pilots determine their altitude above ground, showed good performance within their frequency band, and VHF antennas for aviation radio displayed stable results. An important finding was that an antenna damaged by a lightning strike started to pick up signals from mobile networks. This underscores the importance of inspections and maintenance, as damage can affect flight safety.
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