Most passive ultrahigh-frequency (UHF) solutions can tell you only that a tag is within a reader’s proximity, and not its precise location. However, phased-array antenna systems, from such companies as Mojix, can tell you an item’s location to within approximately 10 feet (3 meters), which is equivalent to the location accuracy of most active RFID system. For low-cost goods, this type of solution might be your best option. You might also look into reusable tags. These would cost more up-front, but might be cheaper in the long term.
—Mark Roberti, Founder and Editor, RFID Journal
Where Might I Find Tiny RFID Tags? »