Far-field passive temperature sensing up to 700°c using a dielectric resonator

This paper presents a novel wireless and passive temperature measurement system for temperatures up to 700°C. The sensor is based on a dielectric resonator composed of zirconium tin titanate (Zr_0.8Sn_0.2TiO₄, ZST) and operates at 2.37 GHz. The measurements are conducted in a chamotte stone oven at a distance of 1.20 m between the sensor and the reader antenna. The external electromagnetic fields of the dielectric resonator were adequate for the far-field coupling without the need to use any conducting part on its surface. This measurement method allows to retain a quality factor higher than 670 at 700°C, which is sufficient for the used RADAR based interrogation unit to keep a satisfying temperature measurement accuracy. The effect of temperature on the tracked sensor resonance frequency, signal-to-noise ratio (SNR) and Q factor are presented. Moreover the concept is suitable for applications operating at high temperatures such as aerospace applications, where the use of passive, wireless and metalization-free sensors is mandatory.