Apparatus and methods for wireless/RFID sensors

A wireless sensor, comprising:

• at least one sensing circuit;
• a modulator operably connected to the at least one sensing circuit and configured to modulate an input signal using variations in input impedance produced by the at least one sensing circuit to produce a modulated output signal, wherein the modulator comprises a multi-port direct conversion structure comprising:
• a first coupler providing a first port for receiving the input signal,
• a second coupler providing further ports, the second coupler being connected to a first sensing circuit and configured to modify the input signal using sensor data obtained by the first sensing circuit,
• a third coupler providing further ports, the third coupler being connected to a pilot sequence generator and configured to modify the input signal using the pilot data generated by the pilot sequence generator, and
• a combiner for combining the modified input signals to produce the modulated output signal;
• and
• a transmitting element operably connected to the modulator to wirelessly transmit the modulated output signal to a receiver.