Surface velocity estimation of fluids using millimetre-wave radar

This paper presents a microwave sensor which allows to measure the surface velocity of fluids via determining the Doppler shift of the scattered signal. To fulfil natural as well as industrial measurement conditions, different distances and spatial arrangements, the design of the sensor exhibits a modular system. Thus, different beam forming components have been developed and can be exchanged easily. A lot of effort has been spent in designing an innovative dielectrical waveguide antenna for near distance measurements of hard-to-reach liquids. This design process will be exposed and the technical suitability will be tested with an exemplary test set-up. The dependency of the signal strength on the angle of polarisation will be investigated and an approach to estimate the velocity from the measured data will be introduced.