Passive Tag

An RFID tag without its own power source, activated by electromagnetic energy from readers. Very inexpensive, unlimited lifespan (no battery to replace), but limited range and functionality. Used for item-level tagging, asset identification at fixed read points, and applications not requiring real-time location.

See Passive RFID entry for complete definition. Passive tag refers to RFID transponder containing no battery, powered by electromagnetic energy from external reader. Passive tags respond to reader interrogation with stored identification data but cannot transmit independently.

Key characteristics: no battery (indefinite lifetime without maintenance), short read range (typically centimeters to several meters depending on frequency and reader power), low cost ($0.05-3 per unit), small form factor (can be tiny labels), and detection only when within reader range (no continuous tracking). Contrast with active tags (battery-powered, longer range, higher cost, continuous transmission capability). Passive tags suitable for checkpoint-based identification (items passing through reader locations) but not continuous real-time positioning.

Common in access control, inventory management, and supply chain applications where checkpoint-based tracking adequate. Used in hybrid industrial tracking systems: passive RFID for low-cost item identification at checkpoints, active RTLS for continuous tracking of high-value assets or safety-critical applications.