Hybrid Active-Passive RFID Tag for Tracking Birds Using Existing Radar Systems

Abstract

RFID “radio-frequency identification” tags are a powerful tool for the identification and tracking of objects across a variety of media. RFID tags have applications in security badges, individual identification tags, short range tracking systems, and other similar devices. These applications are all relatively short range, r, (r < 100) m and thus require low power. Through the use of the WSR-88d (NEXRAD) weather radar system this technology can potentially be extended to long range (r > 100) km applications. With the WSR-88d’s large realized gain of 45.5 dB and high transmitted power 700 kw it is possible to achieve a bird tracking device that can be passively used with the already developed weather infrastructure. The solution is realized as a small form factor enclosure that is attached to the animal being observed. Each individual tag represents an unique identifier that can distinguish it from the other versions of the tag. The transmitter’s portion of the tracking procedure is done by observing the unique coded back scatter of each individual tag via the WSR-88d’s pulses to check the location and path of the animal as it travels across the United States. In this study, an RFID tag compatible with the NEXRAD weather radar network is produced. This tag demonstrates the ability to backscatter pulse-to-pulse across the entire pulse repetition frequency range of the NEXRAD network. Multiple modulation schemes are presented and detailed in the results chapter. These modulation schemes are demonstrated across a variety of power ranges as well to insure functionality as the bird changes distance from the radar.