A Low-Profile Wireless Passive Temperature Sensor Using Resonator/Antenna Integration Up to 1000°C

A novel wireless temperature sensor is presented herein for high-temperature applications. This sensor is robust in harsh environments using stable materials and purely passive structures. The resonant frequency of the sensor is determined by the temperature-dependent dielectric constant of the substrate material. The temperature can be wirelessly detected by sensing the resonant frequency of the sensor. The integration of the resonator and antenna enables realization of low-profile and compact sensors. Measured resonant frequency of the sensor decreases from 5.12 to 4.74 GHz when the temperature increases from 50 degrees C to 1000 degrees C. This corresponds to a variation of dielectric constant from 9.7 to 11.2 for the alumina substrate. The presented sensor structure is scalable in size or frequency based on the design requirements.