| 摘要 |
The invention relates to a sensor and a system for measuring pressure, variation in sound pressure, a magnetic field, acceleration, vibration, or the composition of a gas. The sensor comprises an ultrasound transmitter, a cavity, and a passive sensor element. In accordance with the invention the sensor includes antenna means for receiving radio frequency signals (f1, f2), and connecting means connecting the antenna to the ultrasound transmitter for using the radio frequency signals for providing energy for driving the ultrasound transmitter. |
