A wireless SAW-based temperature sensor for harsh environment

A SAW-based temperature sensor system is presented. Much effort was placed in the development of a high temperature resistive transponder compromising of both a SAW device and an antenna stable up to 400 /spl deg/C for at least a few days. The system solution also includes a low-cost reader unit employing the FSCW (frequency stepped continuous wave) principle operating in the ISM band from 2.4 GHz to 2.4835 GHz. Spare space on the SAW device has been employed also to implement an ID for identification purpose. Hence, this solution also allows for tagging of objects exposed to harsh environments.