A Continuous-Mode Single-Antenna Harmonic RFID Tag

In this letter, a single-antenna-based compact harmonic RFID tag having efficient power harvesting topology is demonstrated. The harmonic RFID receives a continuous signal at the fundamental frequency (
$fo = 434$
MHz) and replies back with modulation at the second harmonic (
$2fo = 868$
MHz). To enhance the read range, the harmonic RFID tag topology was designed to harvest energy simultaneously while performing modulation in a continuous mode. Furthermore, the harmonic RFID allows the use of lower modulation rates to reduce power consumption, thus further enhancing the read range. Performance at different modulation rates is demonstrated. Overall, a compact and efficient harmonic RFID is demonstrated with a read range of 8 m at a 1-kHz tag data modulation rate and 30-dBm transmit power.