Can I Track Items at Long Distances Using RFID?

Near Field Communication (NFC) readers currently used in smartphones are designed for short-range reading only. Even if you were to place an ultrahigh-frequency (UHF) reader in a smartphone, there would not be enough energy available to locate a tag from that distance, because the phone manufacturers limit the amount of power available to peripherals in order to prevent a peripheral from draining the battery. Even if those restrictions were lifted, you would still not be able to read a passive tag from that range.

It might be possible to create a proprietary phone add-on that could interrogate an active (battery-powered) tag. That way, the tag would broadcast a signal and the phone reader would be able to pick it up. But that would also raise tag cost to around the $50-per-tag range, which would make it useless for most consumer applications.