Would radio frequency identification be a good technology to deploy over long distances?
Radio frequency identification is a relatively short-range automatic-identification technology. Passive low-frequency (LF) and high-frequency (HF) tags can be read from a distance of up to 3 feet (0.9 meter), while passive ultrahigh-frequency (UHF) RFID transponders can typically be read from 10 to 20 feet (3 to 6 meters) away. You could extend the read range by using a larger antenna on the transponder to harvest more energy from the reader and send back a stronger signal. I've seen passive tags read from 80 feet (24.4 meters) using an ordinary fixed RFID reader.
There are beam-steerable RFID reader antennas that can increase the read range of an ordinary passive UHF RFID tag to more than 60 feet (18.3 meters), but if you wanted to read tags from further away than this, you would need to use a battery-assisted passive (BAP) UHF RFID tag or an active tag. In the case of a BAP tag, the battery would be used to power up the chip, which would then reflect back a signal like a passive tag, but because the battery was helping to power the chip, more energy would be available to send back a stronger signal, resulting in a longer read range.
Active RFID transponders have an energy source (usually a battery), which they use to broadcast a signal. The read distance can be 3,000 feet (914 meters) or more. There are a variety of active RFID systems available on the market; the right one to use would depend on your particular application.
I hope this answers your question, and I hope to see you at RFID Journal LIVE! 2020, where you can learn more about the different types of tags.
—Mark Roberti, Founder and Editor, RFID Journal
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