Contactless Temperature Sensing Utilizing Resonant Antenna Loaded with Thermistor

In this paper the passive sensor allowing contactless temperature measurements is described. The solution is dedicated for industrial rotating equipment like reciprocating engines or compressors operating in hazardous (eg. explosive) environment. Presence of mineral oil particles and combustion products does not allow to use common optical measurement methods. The defined user case requires easy sensor installation and no wired or battery power supply. As any service requires stopping the entire machinery and processes it drives, the simplicity and robustness of the sensor is an advantage. The proposed solution is based on a microstrip resonant antenna operating in 2.4 GHz ISM band and loaded with thermistor directly or via a coaxial line.