What Is Radiofrequency Identification?

Radiofrequency identification (RFID) is a technology for the automatic identification and data capture of objects, animals, or persons using radio-frequency electromagnetic fields to transfer data between a tag and a reader without physical contact. The technology encompasses the full system architecture from the integrated circuit and antenna embedded in the tag through the reader hardware, communication protocols, middleware, and enterprise software that consume the captured data. RFID operates across several frequency bands, each suited to different applications: low frequency (LF, 125–134 kHz), high frequency (HF, 13.56 MHz), ultra-high frequency (UHF, 860–960 MHz), and microwave (2.45 GHz and above), with operating range, data rate, and environmental robustness varying significantly among them.

The technical foundations of RFID span RF design, IC design, antenna engineering, digital communications, and embedded systems. Compound semiconductor materials such as GaAs and GaN appear in active RFID tags and readers operating at higher frequencies, while silicon CMOS dominates passive UHF tags and near-field HF devices because of its low cost and compatibility with high-volume manufacturing.

Tag and Reader Hardware

The tag is the data carrier of the RFID system. It consists of a radiofrequency integrated circuit bonded to an antenna, with the IC containing memory, a modulator, and control logic. Passive tags harvest operating energy from the reader's field via inductive coupling (at LF and HF) or backscatter modulation (at UHF), requiring no battery and enabling extremely low manufacturing costs. Active tags carry an integral power source and transmit their own signal, extending read range to tens of meters at the cost of battery replacement. The reader, or interrogator, generates the interrogation field, demodulates tag responses, and passes the decoded identifier to the system software. Readers range from handheld devices with a single antenna to portal installations with multiple active antennas arranged to cover all faces of a read zone. RFID reader and tag designs are covered in depth in IEEE Xplore resources on RFID system overview, which addresses antenna design, modulation schemes, and reader architectures.

System Architecture and Standards

An RFID deployment integrates several layers: physical tag-reader communication, air interface protocols, middleware that filters and aggregates reader data, and application software. The air interface at UHF is governed by the ISO/IEC 18000-63 standard (equivalent to EPCglobal Gen2), which defines the modulation, encoding, and anti-collision procedures that allow a single reader to inventory hundreds of tags per second. At HF, ISO 15693 and ISO 14443 define two common air interfaces, the latter being the basis for contactless payment cards and electronic passports. The IEEE 1451.7 standard extends RFID into sensor-coupled applications by defining protocols for integrating transducer data into RFID data exchanges. Transceivers within readers must achieve low phase noise and precise carrier frequency control to meet regulatory emission masks and to support the weak backscatter signals returned by passive UHF tags.

Near-Field Communication and Adjacent Technologies

Near-field communication (NFC) is a subset of HF RFID operating at 13.56 MHz with a maximum range of about 20 cm, standardized in ISO 18092 and implemented widely in smartphones for contactless payments, transit ticketing, and peer-to-peer data exchange. NFC inherits the ISO 14443 air interface and adds peer-to-peer mode, allowing two NFC-capable devices to exchange data bidirectionally. Wireless identification more broadly also includes Bluetooth Low Energy (BLE) beacons and ultra-wideband (UWB) tags, which offer advantages in location precision but at higher hardware cost than passive RFID. Product codes such as the Electronic Product Code (EPC) provide a standardized data schema that RFID tags carry, enabling interoperability across supply chain partners. The RFID and IoT integration literature documents how RFID serves as the identification layer in Internet of Things architectures, feeding real-time location and identity data into intelligent sensor networks and wireless infrastructure.

Applications

Radiofrequency identification has applications in a wide range of fields, including:

• Retail and logistics, where passive UHF tags enable item-level inventory visibility and automated checkout
• Access control and workforce management, using HF or LF cards for facility entry and time-attendance recording
• Animal identification, including livestock ear tags and companion animal microchips conforming to ISO 11784/11785
• Contactless payment systems and transit fare collection based on NFC and ISO 14443
• Healthcare, for patient wristband identification, medication administration verification, and surgical instrument tracking
• Wireless infrastructure monitoring in smart buildings, where RFID tags on assets enable automated location and maintenance scheduling