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How does RFID work?

In simple terms, an RFID system consists of three parts: an RFID tag or smart label; an RFID reader/writer (also called an interrogator); and software (also called middleware) that communicates the acquired data to an IT system or the Internet of Things (IoT). Depending on the application requirements, system components need to be carefully selected to meet the required performance, accuracy, and reliability.

RFID Tags

RFID tags come in many shapes and sizes and can be either "passive" or "active." But the most common are passive tags, meaning they do not require an integrated power source such as a battery. Passive tags typically consist of an RFID inlay and a casing to protect them from physical damage. The inlay consists of a small silicon microchip that stores the digital ID and other data, attached to an antenna on a thin substrate such as paper or plastic (PET) film. The passive tag's antenna receives radio waves from the reader/writer and transmits them to the microchip, which harvests that energy and uses it to send wireless signals back to the reader/writer.

The thin size of the inlay makes it easy to embed into a traditional tag, making it a smart tag, or into very strong plastic (hard tag) or biocompatible glass (glass tag) for use in extremely harsh environments or injection into animals.

Types of RFID

RFID systems are classified into three main radio frequency ranges: low frequency (LF), high frequency (HF) and ultra-high frequency (UHF). They differ by application, maximum read range, and type of RFID tag and reader used.

Ultra-high frequency (UHF)

UHF RFID systems operate in the frequency range of 860 to 960 MHz. Typical read ranges are from close contact to over 20 meters, making them very versatile and can be used in applications such as inventory and supply chain management, smart manufacturing, airline baggage tracking, sports timing, etc.

Within the frequency range, there are two main regional sub-bands defined by regulatory agencies. The European Telecommunications Standards Institute (ETSI) defined 865 - 868 MHz for use in RFID, and the U.S. Federal Communications Commission (FCC) selected 902 - 928 MHz. Some of our RFID tags and inlays are designed for use with either the FCC or ETSI frequencies, and many newer products support both bands.

Compared to HF and LF, UHF systems support longer read ranges, enable cost-effective inlays and tags in a variety of sizes and shapes, and can read loose items quickly, but are more susceptible to radio wave interference from metal or conductive materials or liquids.

High Frequency (HF) and Near Field Communication (NFC)

HF and NFC RFID systems operate in the 13.56 MHz frequency band with read ranges from near contact to 50 cm. Typical applications include library media management, automated manufacturing, gaming chip management, ID cards, contactless payments with NFC payment cards or smartphone apps, and consumer engagement. HF tags require special readers, while NFC tags can be read by almost any smartphone at a distance of a few centimeters.

With billions of NFC-enabled smartphones on the market today and more consumers becoming accustomed to contactless payments, there is a bright future for consumer interaction and other new consumer-centric applications using NFC tags.

Low Frequency (LF)

Most LF systems operate in the 125 - 134 kHz band, achieving a read range of up to 10 cm. Typical applications include animal identification, access control, car access, and environments with high density liquids and metals.

LF systems have lower data rates and read distances than UHF and HF, but LF systems are suitable for use in harsh environments.