Pressure based wireless sensor and applications thereof

A passive wireless tire pressure sensor comprises:

• an antenna;
• a tuning circuit operably coupled to the antenna;
• a pressure sensing circuit operably coupled to at least one of the antenna and the tuning circuit, wherein the antenna, the tuning circuit, and the pressure sensing circuit collectively have one or more radio frequency (RF) characteristics and wherein the pressure sensing circuit causes the one or more RF characteristics to vary with varying sensed pressures;
• a second antenna;
• a power harvesting circuit operably coupled to the second antenna, wherein, when the second antenna receives an RF signal, the power harvesting circuit converts the RF signal into a power supply voltage;
• a processing module powered via the power supply voltage, wherein the processing module is operable to:
• detect a variance of the one or more RF characteristics from a desired value of the one or more RF characteristics;
• in response to the detecting of the variance, adjust the tuning circuit to substantially re-establish the desired value of the one or more RF characteristics;
• and
• generate a message regarding the adjusting of the tuning circuit, wherein a level of the adjusting of the tuning circuit is representative of a variance of pressure sensed by the pressure sensing circuit;
• and
• a transmitter powered by the power supply voltage, wherein the transmitter transmits the message.