Dielectrically-Loaded Cylindrical Resonator-Based Wireless Passive High-Temperature Sensor

• Published in: Sensors (Basel, Switzerland) Vol. 16; no. 12; p. 2037
• Main Authors: Xiong, Jijun, Wu, Guozhu, Tan, Qiulin, Wei, Tanyong, Wu, Dezhi, Shen, Sanmin, Dong, Helei, Zhang, Wendong
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.12.2016; MDPI
• Subjects: Aluminum oxide; Background noise; Backscattering; Broadband; Ceramics; Compensation; Coplanar waveguides; Devices; dielectric resonator; Dielectrics; High temperature; high-temperature environment; Interrogation; Peak frequency; Permittivity; Radio signals; relative permittivity; Resonant frequencies; Resonators; Sensors; Signal to noise ratio; Slot antennas; Substrates; temperature sensing; Temperature sensors; dielectric resonator; relative permittivity; temperature sensing; high-temperature environment
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s16122037

The temperature sensor presented in this paper is based on a microwave dielectric resonator, which uses alumina ceramic as a substrate to survive in harsh environments. The resonant frequency of the resonator is determined by the relative permittivity of the alumina ceramic, which monotonically changes with temperature. A rectangular aperture etched on the surface of the resonator works as both an incentive and a coupling device. A broadband slot antenna fed by a coplanar waveguide is utilized as an interrogation antenna to wirelessly detect the sensor signal using a radio-frequency backscattering technique. Theoretical analysis, software simulation, and experiments verified the feasibility of this temperature-sensing system. The sensor was tested in a metal-enclosed environment, which severely interferes with the extraction of the sensor signal. Therefore, frequency-domain compensation was introduced to filter the background noise and improve the signal-to-noise ratio of the sensor signal. The extracted peak frequency was found to monotonically shift from 2.441 to 2.291 GHz when the temperature was varied from 27 to 800 °C, leading to an average absolute sensitivity of 0.19 MHz/°C.