A Passive Harmonic RFID Tag and Interrogator Development

In this paper, a passive harmonic radio frequency identification (RFID) tag and a simple interrogator to actuate the tag and obtain the identity (ID)/IP address from the tag are presented. The harmonic RF tag was implemented using transceiver antennas, a lumped element-based non-linear transmission line (NLTL), an energy harvester and an ultra-low power digital modulation circuit. The digital modulation circuit generated the ID and the NLTL was modulated at that specific ID. The harmonic tag can operate at a minimum received power of -6 dBm. Combining antennas with the tag, a read range of 1.8 m was achieved at a transmitted power of 18 dBm at 434 MHz. A simple interrogator design was proposed to activate the tag and decode the transmitted ID. The design and working principle of the tag along with the interrogator are discussed in detail. The results of this paper are compared to data reported in open literature for alternate RFID designs.