Fraunhofer Institute has developed a harmonic radar system that can locate persons in the water. The Institute's High-Frequency Physics and Radar Technology FHR worked with partners - the Institute for Microwaves and Plasma Technology of the FH Aachen and Raytheon Anschütz. If a person goes overboard on the high seas, it is almost impossible to detect them in the water with conventional ships' radar systems, since waves reflect the radar signal in different directions. The research partners' SEERAD system works even at great distances. It uses frequency-converting transponders, or tags, that, when integrated in rescue vests, reflect the signal transmitted by a ship's radar at double the frequency. This enables the detection of very small objects over distances of up to ten kilometers. SEERAD is not that much bigger than a conventional ship's radar system, even though it accommodates two antennas operating on different frequency bands. "We are proud that we have succeeded in making the antenna seaworthy, weather-proof against rain, sun, wind and salt water. The conditions at sea also bear a heavy burden on the mechanics, and our antenna should be able to withstand this," says Dr Thomas Bertuch, project manager at Fraunhofer FHR.