Long-Range Battery-Free UHF RFID With a Single Wire Transmission Line
Apoorva Sharma, Alexander T. Hoang and Matthew S. Reynolds
IEEE Sensors Journal
Vol. 17, No. 17,
1st January 0001
Singel wire transmission line, surface wave transmission line, goubau line, long range RFID, extreme environments, distributed sensing, passive UHF RFID
We present a long range passive (battery-free) RFID and distributed sensing system using a single wire transmission line (SWTL) as the communication channel. A SWTL exploits guided surface wave propagation along a single conductor, which can be formed from existing infrastructure such as power lines, pipes, or steel cables. Guided propagation along a SWTL has far lower losses than a comparable over-the-air (OTA) communication link, so much longer read distances can be achieved compared to a conventional OTA RFID system. In a laboratory scale experiment with an ISO18000-6C (EPC Gen 2) passive tag, we demonstrate an RFID system using an 8 mm diameter, 5.2 m long SWTL. This SWTL has 30 dB lower propagation loss than a standard OTA RFID system at the same read range. We further demonstrate that the SWTL can tolerate extreme temperatures far beyond the capabilities of coaxial cable, by heating an operating SWTL conductor with a propane torch having a temperature of nearly 2000 C. Extrapolation from the measured results suggest that a SWTL-based RFID system is capable of read ranges of over 70 m assuming a reader output power of +32.5 dBm and a tag power-up threshold of -7 dBm.
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