The Chip (Integrated Circuit)

The chip is the brain of the tag. It stores data and handles communication with RFID readers. Most passive UHF RFID chips contain several distinct memory banks. The EPC (Electronic Product Code) memory is the primary identification space, typically offering 96 or 128 bits for a unique serial number. The TID (Tag Identifier) memory holds a factory-programmed, read-only number that uniquely identifies the chip itself and cannot be altered. Many chips also include User memory, which can range from zero to several kilobits, giving businesses extra space to store custom data like batch numbers, maintenance records, or temperature logs directly on the tag.

Chip size has shrunk dramatically over the years. Modern RFID chips can be smaller than a grain of sand, which has opened the door to thinner, more flexible tag designs. Sensitivity has improved too, meaning tags can be read from greater distances even with less power.

The Antenna

The antenna is what makes wireless communication possible. In a passive RFID tag, the antenna captures energy from the reader’s radio signal, powers the chip, and then reflects a modulated signal back. Antenna design directly affects read range, orientation sensitivity, and performance on different materials.

Most UHF tag antennas are flat, etched, or printed conductive patterns, often made from aluminium or copper. A simple dipole antenna works well for general use, while more complex designs like dual-dipole or loop antennas help the tag perform reliably regardless of its orientation to the reader. Tags designed for use on metal surfaces often include a spacer or ground plane in the antenna design to prevent signal cancellation.

The Substrate

The substrate is the base material that holds the chip and antenna together. It can be a thin plastic film like PET or polyimide, a paper backing, or a rigid material such as FR4 or ceramic. The choice of substrate determines how flexible, durable, and heat-resistant the finished tag will be.

Inlay, Label, and Hard Tag

These three components come together in different form factors depending on the application. An inlay is the most basic assembly: the chip and antenna bonded to a thin substrate. Inlays are typically sold on rolls and are the building blocks for other tag types.

A label (sometimes called a smart label) is an inlay sandwiched between a printable face stock and an adhesive backing. Labels are popular in retail and logistics because they can be printed with barcodes, branding, or human-readable text while also carrying RFID capability.

A hard tag encases the inlay in a rugged housing, often made from ABS plastic, polycarbonate, or even epoxy-filled metal shells. Hard tags are built to survive harsh environments such as manufacturing floors, outdoor asset yards, or autoclave sterilisation cycles in healthcare. They are typically attached with screws, rivets, cable ties, or industrial adhesive.

Choosing the right combination of chip, antenna, substrate, and form factor is one of the most important decisions in any RFID deployment. A well-matched tag ensures reliable reads, long service life, and accurate data capture across the full range of operating conditions.

The post Anatomy of an RFID Tag: Chip, Antenna, Substrate first appeared on RFID News.