PCB impedance tuning to achieve wideband and high acceptance of coil antenna length variation

A tire monitoring device, comprising:

• at least one sensor mounted on a printed circuit board (PCB), the at least one sensor configured to detect at least one condition of a tire;
• radio frequency identification (RFID) circuitry mounted on the PCB, the RFID circuitry coupled to a coil antenna mounted on the PCB, the RFID circuitry configured to harvest energy and transmit monitored tire data in response to a received interrogation signal, where the RFID circuitry is tuned to receive a radio frequency (RF) interrogation signals in a frequency band from at least 868 MHz to at least 915 MHz;
• wherein the RFID circuitry comprises a matching network that couples the coil antenna to energy harvesting circuitry and RFID transponder circuitry, the matching network configured for impedance matching over the frequency band;
• wherein the energy harvesting circuitry comprises energy harvesting chips coupled to the matching network;
• wherein the matching network comprises at least one LC filter connected to the coil antenna and an LC circuit connecting the energy harvesting circuitry to the at least one LC filter;
• and
• processing circuitry mounted on the PCB, the processing circuitry configured to obtain the monitored tire data from the at least one sensor in response to a received interrogation signal and provide the monitored tire data for transmission by the RFID circuitry.