And what is its power source?
A passive tag is a radio frequency identification transponder that does not have a power source. It is called “passive” because it does not actively broadcast a signal. Instead, it gathers energy from radio waves emitted by a reader antenna and then reflects back a signal to that antenna.
Passive tags generally have a shorter read range than active tags, since they cannot emit a signal. They are also usually less expensive, since they lack a battery or other power source and do not require protective housing (though you can purchase passive tags with protective housings for certain applications).
Incidentally, rfidjournal.com maintains an extensive glossary, and terms in that glossary are highlighted in every article. So if you click on a term in a story, you will be able to view its definition. “Passive” is not currently defined in our glossary, but I will add it.
—Mark Roberti, Founder and Editor, RFID Journal
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