A Second Generation In-Car Tire Pressure Monitoring System Based on Wireless Passive SAW Sensors

A complete pre-production in-car tire pressure monitoring system, employing 433 MHz SAW resonators as sensing elements is presented in this paper. The SAW sensing element incorporating three one-port resonators fabricated on a single substrate and connected to an antenna is described, along with calibration models for the sensor. An issue of sensor antenna tuning and sensor matching is investigated. A method of SAW sensor wireless interrogation is presented and the electronic interrogation unit is described. Experimental data characterizing accuracy of the remote resonant frequency measurement is presented