Detection of water drop volume based on Chipless RFID radar approach

In this paper the principle of radar commonly used in chipless RFID is implemented to detect the presence of water in contact with a resonant radar target. It is shown how it is possible to determine very precisely the time at which the water on the tag has completely evaporated. Based on this observation, a method for determining the volume of a drop of water of a few μl on a resonant scatterer is introduced. The measurements carried out in a real environment are in very good agreement with the simulations and make it possible to consider the detection of the presence of water in contact with an RFID tag without a chip and to evaluate its volume.