Design of temperature sensor array in smart electric grid based on SAW resonators

The sensor array with six sensors working at the frequency range of 429-436 MHz is designed and fabricated. The temperature sensitivity can be accurately controlled by the metallization thickness of the resonator on quartz substrate to keep the temperature-induced frequency shifts of each sensor within a limited bandwidth over a wide operating temperature ranging from -40°C to +150°C. The thermal parameters of sensor encapsulation are optimized according to the high voltage switchgear application. In order to meet the real-time requirement of sensor array measurement, discrete Hartley Transform (DHT) and the method of fast searching center frequency of sensors by comparison of I/Q and interrogation signals are used to reduce the query time, greatly improving the efficiency of polling of the sensor array. The measurement uncertainty of the practical SAW temperature sensor is less than 1°C, and the sensitivity of sensor is up to 4 KHz/°C.