Sensor add-on for batteryless UHF RFID tags enabling a low cost IoT infrastructure

The paper presents an antenna transducer prototype at 915MHz for a batteryless ultra high frequency (UHF) radio frequency identification (RFID) transponder (tag) sensor add-on. By using low cost and low maintenance batteryless RFID sensor tags in a home environment, a low cost internet of things (IoT) infrastructure can be provided. The batteryless or rather passive UHF RFID sensor tag is realized by using the tag antenna as the sensing device. The prototyped antenna transducer allows to detect three specific water filling levels in a can to sense for example the filling level of a coffee machine in a smart home environment. The transducer prototype provides a high efficiency of 92%and thus guarantees for the first time a reliable and stable power supply to the passive RFID tag chip at each sensing state.