Field powered 5.8 GHz ISM band transponder for sensors integrated in metallic objects

This paper presents the new design of a field powered microwave transponder fully integrated into a metallic object. The transponder operates in the 5.8 GHz ISM band and consists mainly of a waveguide antenna, a rectifier, a low-power microcontroller and a temperature sensor. The transponder has been integrated 4.5 cm deep into a metallic work piece. Depending on the microcontroller code the transponder can be used for identification or sensor applications. The realized system is able to identify the object and to measure and transmit the inner temperature to a reader. An operating range and a data rate up to 51 cm and 333.3 kb/s respectively have been achieved.