RFID (Radio-Frequency Identification)

A technology using electromagnetic fields to automatically identify and track tags attached to objects. Includes both passive RFID (powered by reader signals) and active RFID (battery-powered). Fundamental technology underlying many RTLS implementations. Ranges from simple identification to real-time location tracking.

RFID is a wireless identification technology that uses radio waves to automatically identify and track objects equipped with RFID tags. While often confused with RTLS, RFID and RTLS serve different purposes: RFID primarily identifies objects passing through fixed reader locations (chokepoints), while RTLS provides continuous real-time position tracking throughout a facility. RFID systems operate in three main frequency ranges, each with distinct characteristics: Low Frequency (LF, 125-134 kHz) with read ranges under 10 cm, used for access control; High Frequency (HF, 13.56 MHz) with ranges up to 1 meter, used in NFC applications; and Ultra-High Frequency (UHF, 860-960 MHz) with ranges up to 12 meters, used in supply chain and inventory management. RFID tags come in two types: passive tags without batteries (powered by reader's RF field, lower cost, shorter range, typically $0.10-$2 per tag) and active tags with batteries (self-powered, longer range, higher cost, $10-$50+ per tag). Active RFID can provide zone-level positioning (identifying which reader zone a tag is near) but lacks the continuous tracking and sub-meter accuracy of dedicated RTLS technologies. RFID's advantages include lower tag costs and simpler infrastructure for chokepoint-based applications, while limitations include read reliability issues (metal and liquids interfere with RF signals), lack of continuous tracking, and limited positioning accuracy. The distinction between active RFID and RTLS has blurred over time, with some active RFID systems offering basic positioning capabilities, though dedicated RTLS technologies (UWB, UWB, Wi-Fi-based) provide superior accuracy and update rates for applications requiring continuous tracking.