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TechnologyCertainty about identity, at a known point.
RFID does not tell you where something is. It tells you what passed a reader, when, and in which direction — from a tag with no battery that costs a fraction of anything powered. Used for what it is, it is unbeatable.
The reader supplies the power. The tag just answers.
A passive UHF RFID tag has no battery. The reader floods the area with RF energy; the tag harvests just enough of it to wake its chip, then replies by modulating how much of that energy it reflects back — backscatter. The result is a tag that costs very little, lasts as long as the label it is printed on, and can be read in bulk.
The dominant air interface is EPC Gen2, standardised as ISO/IEC 18000-63.
Not a position. An event.
This is the distinction that decides whether an RFID project works. A read is a statement that a specific item was inside a specific antenna's field at a specific moment. Chain those events together at the right choke points and you can reconstruct a great deal — but you never interpolated between them.
Three RFIDs, often confused.
| Family | Typical use | Character |
|---|---|---|
| LF, 125–134 kHz | Animal identification, immobilisers, access fobs | Very short range, but tolerant of water and metal |
| HF / NFC, 13.56 MHz | Cards, tickets, close-coupled item identity, phone taps | Centimetres, and deliberate. NFC reads one tag at a time; HF vicinity tags support several |
| UHF, 865–867 MHz in India | Inventory, portals, logistics, retail | Metres, and hundreds of tags per second |
When people say “RFID” in a logistics or retail context they almost always mean UHF. In an access-control context they almost always mean HF. Those two share an acronym and very little else: HF couples inductively in the near field and the tag replies by load modulation, while UHF works in the far field and the tag replies by backscatter. Different physics, different failure modes, different suppliers.
Use it when the answer is an identity.
- Use RFID when items must be identified individually and in volume. A bulk read counts a room of stock in the time a manual count spends on one aisle.
- Use RFID when movement passes through natural choke points. Doors, gates, conveyors and workstations are where it is cheapest and most certain.
- Use RFID when the tag budget rules out anything powered. Tagging a hundred thousand items is routine here and economically absurd with UWB.
- Do not use RFID when the read point cannot be controlled. It needs a choke point, an antenna aimed at it, and goods that present themselves in a predictable way.
- Do not use RFID when you need to know where something is between read points. No amount of extra readers turns it into a positioning system.
Which tag goes on what.
Pairing RFID with UWB is the most common combination we build, and in practice the whole design comes down to one decision: which things are reusable. Reusable things — the trolley, the tote, the fixture, the pallet — carry the powered tag, because the cost is amortised over years of circulation. Everything that leaves and does not come back takes a printed label.
Get that split wrong in either direction and the economics collapse: powered tags on consumables are unaffordable, and passive tags on the carrier leave you blind between read points.
Start with a site, not a specification.
Send us the space, what moves in it, and the accuracy the decision actually needs. We will tell you which of the three technologies fits, which does not, and what a first deployment would involve.