It really depends on your definition of “close-range.” Passive high-frequency (HF) systems based on the ISO 14443 standards are designed for very short-range communication (only a few inches). This standard is intended for financial transactions, in which you would not want to capture data from other transponders that might be in the area, or have people eavesdrop on the tag-to-reader communication.
Passive HF solutions based on the ISO 15693 standards are designed for communication within two feet or so. Transponders based on this standard are used for access control and inventory management. Passive ultrahigh-frequency (UHF) systems are designed to read tags within 20 feet or so, depending on the object on which a tag is placed, as well as the environmental conditions and other factors. There are special passive tags that can be read from longer distances.
If you are concerned about the reliability of passive systems because they do not broadcast a signal in the way that active tags do, this can be an issue in some instances. For example, you would not be able to read a passive tag on a case of canned goods in the middle of a pallet of such products, as the signal would not penetrate through the metal cans. But for tracking most items, passive systems can be designed to work effectively within a range of 20 feet or so. It’s best to work with a knowledgeable systems integrator who can design a solution to work reliably to meet your needs.
—Mark Roberti, Founder and Editor, RFID Journal
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