High-sensitivity, AM-modulated harmonic transceiver for wireless sensing

Described is a zero power transceiver that is designed to receive a low-power RF signal at a fundamental frequency, double the frequency with high efficiency, and retransmit the second harmonic. The specific emphasis of this reported work was to demonstrate a means of imparting amplitude modulation onto the retransmitted harmonic in response to some environmental stimulus - in this case a DC bias voltage - to facilitate use of the transceiver in wireless sensing applications. The 1.3/2.6 GHz transceiver zero-bias conversion efficiency is approximately 2% (-17 dB) at received input power levels in the micro-Watt range. A change in the conversion efficiency of 10 dB per 100 mV is achieved through DC biasing of the multiplier.