A method for execution by a RFID tag includes receiving, from an RFID reader, an RF signal, where the RF signal has a carrier frequency of a plurality of carrier frequencies that span a broad frequency band. The method further includes adjusting input impedance of the RFID tag over a range of input impedances, where the input impedance of the RFID tag is based on one or more of impedance of the RFID tag's antenna and tank circuit. The method further includes monitoring power level of the received RF signal over the range of input impedances. The method further includes selecting the input impedance of the range of input impedances providing a substantially maximum power level of the received RF signal, where the substantially maximum power level corresponds to the carrier frequency being substantially equal to a resonant frequency of at least one of the antenna and the tank circuit.