The OTT RLS (radar level sensor) is a radar sensor for non-contact water level measurements at surface waters. The sensor uses impulse-radar technology to determine the water level. The RLS is mounted above the water surface e.g.: at bridges or auxilliary constructions. Its solid, relatively light and water-proof housing is easy to install. Its extremely low energy consumption (active: <12mA @12V), the large power supply range and standardized interfaces make the OTT RLS very flexible for different of applications. The RLS covers a measurement range of up to 35m. It is specifically designed for the use in open air locations that have no requirement for mains power supply. The special flat antenna design construction and its minimal energy consumption makes the OTT RLS a economical, practical and reliable alternative to conventional level gauges.