What Is an RFID Tag?

RFID tags consist of an integrated circuit (IC) attached to an antenna with typically a small coil of wires plus some protective packaging (like a plastic card) as determined by the application requirements. Tags are sometimes called 'transponders', and sometimes are called inlays, although technically an inlay is a tag mounted on a substrate that is ready to be converted into a smart label.

RFID tags can come in many forms and sizes. Some can be as small as a grain of rice. Data is stored in the IC and transmitted through the antenna to a reader. RFID tags are either no battery or self-powered by a battery. Tags also can be read-only (stored data can be read but not changed), read/write (stored data can be altered or rewritten), or a combination, in which some data is permanently stored while other memory is left accessible for later encoding and updates.

A tag power source can be passive, semi-passive or active, they are designed to function on specific frequencies or frequency ranges and come in many form factors such as labels, wristbands, buttons or embedded into items.

How Do Rfid Tags Work?

RFID Tags contain electronically-stored information that acts as a label for object identification. Tags identify, categorize and track specific assets. They contain more information and data capacity as compared to barcodes. Unlike barcodes, in an RFID system, many tags are read simultaneously and data is read from and written to a tag. You can categorize RFID tags in different ways by power source, frequency and form factor. In order to function, all tags need power to energize the chip and to transmit and receive data. The way the tag receives its power determines whether it is passive, semi-passive or active.

The majority of passive tags use EEPROM memory. Some are laser programmed at the silicon level. Many active tags utilize battery-backed SRAM. Passive tags (non-battery) typically have anywhere from 64 bits to 1 kilobyte of nonvolatile memory.

Active tags, such as those used in military tags, have memories as high as 128 kilobytes.

The typical operating temperature for an RFID inlay (tag) found in most smart labels is between -25º C and 70º C. Storage temperature typically is between -40º C and 85º C. These values will vary from manufacturer to manufacturer and will depend on the tag components. There are industrial tags available in the market that will withstand temperatures as high as 250º C, which could, for example, stand up to heat sterilization requirements for medical items.

What are the types of RFID Tags?

General Purpose

Tags that feature RFID inlays designed to provide optimal read ranges in most applications; Typically smaller in size, they are available in paper and synthetic materials for use on non-metallic surfaces, plastics or corrugate.

Advanced

Tags that feature inlays that offer a higher level of read performance when placed on or near challenging materials or need to be read at an angle and where longer ranges are required. Typically larger in size, they are available in paper and synthetic materials for use on non-metallic surfaces, plastics or corrugate.

Specialty

Labels with special designs featuring leading inlays that enable longer read ranges on-metal or for challenging applications.

Flag: Label design that flags away from an asset’s surface either distancing the inlay from it, or works with it, to provide reliable readability.

On-Metal: Label features a foam layer between inlay and adhesive to reduce the interference of metal to provide reliable readability.

Encapsulated Tags: Inlay inserted between two tag materials for applications where adhesive is not needed.

What are RFID Tags used for?

RFID Tags are used to identify and track any assets. They help to improve efficiency as they can scan a large number of tags simultaneously or those that could be inside a box or hidden from view.

RFID tagging provides visibility of product movement, streamlines distribution, improves demand forecasting, and makes manufacturing more responsive. Some of greatest advantages of RFID have been demonstrated in item-level deployments at apparel retail stores. Item-level tagging, where small non-descript RFID tags are typically embedded in existing apparel hang tags, are helping solve retailers’ challenges including out-of-stock levels, inventory accuracy, and helping customers quickly and easily find the size, style and color they are looking for.

Both General Purpose and Advanced tags can also be used in a variety of applications such as in Transportation and Logistics in distribution, shipping and receiving, warehouse operations including case, pallet and cross-docking applications. In Manufacturing, applications include work-in-process, product labeling, product ID/serial numbers, security and product lifecycle tagging. In Healthcare, they can be used for patient ID, specimen, laboratory and pharmacy labeling, document and patient records management.

Specialty labels are designed for use of more challenging applications. In Transportation and Logistics, they are used for fleet management and to track metal and liquid-filled containers. In Manufacturing, they can be used for asset tracking of tools, fixtures, metal parts, returnable containers and chemical drums. In Retail, for identification of jewelry, sunglasses and other small delicate items. IT asset tracking of mobile computers, printers, antennas and infrastructure components. Finally, in Healthcare, they can be used to track wheelchairs, beds, oxygen canisters, IV pumps and medical diagnostic tools.

How to Read Rfid Tags?

An RFID Reader is a key component of an RFID Solution. Readers activate a tag within its range and then collects the tag data. Readers also have the capability to write or encode an RFID tag as well. While a reader can process numerous tags at one time, it can recognize each individual tag and can prioritize of all the collected data. Readers use algorithms and filtering of tag data to read all of the incoming data and can also isolate particular tags based on certain logic and its importance to a particular process. For example, a reader can process all tags in a given area but has the ability to focus on a particular tag in order to facilitating finding or locating that particular item more efficiently.

There are different types of RFID Reader including fixed and passive UHF which come in a variety of shapes, sizes and price range. Knowing the environment and application will help narrow down the choices. For example, a small retail stockroom may use a fixed reader at the transition door to read products moving in and out of the backroom whereas a shipping or receiving dock would use an industrial fixed reader in a dock door portal installation to read pallets coming on and off of a truck. A large store selling floor may use a ceiling mountable fixed reader to cover the selling floor. Fixed readers also incorporate antennas as part of the solution. It is the antenna that emits the power and captures the data back from the tag to pass back to the reader.

Handheld readers are typical when it is necessary to read the asset in place, they perform the same function as fixed readers however they allow for flexibility in the workplace. Handheld readers by nature go to the actual asset, they perform in wider ranges of environment and are a cost-effective solution for RFID reading.

Handhelds also offer both RFID and barcode reading capabilities and can be leveraged to run current standard applications as well as specific RFID functions. Handhelds, like fixed readers also come in different form factors both integrated with a mobile terminal as well as the sled variety that can be paired with a mobile computer of a customer’s choice.

What is the difference between active and passive tags?

Active RFID requires the tags to have their own power (usually a battery) and transmitter to broadcast a signal to the RFID reader. They can store more data, have a longer read range and are an excellent choice for high accuracy solutions that require tracking in real time. They are larger due to the need for a battery, and are generally more expensive. The receivers sense one-way transmissions from active tags.

Passive RFID has no power source, and uses an antenna and an integrated circuit (IC). The reader sends out radio waves that power the IC when it’s within the zone of the reader. These tags generally are limited to providing basic identification information, but can be small in size, have a long lifespan (20+ years) and are low cost.

How do passive RFID tags work

Passive RFID tags contain a low-power integrated circuit (IC) attached to an antenna and enclosed with protective material (label media) as determined by the application. The most compact RFID devices use an IC as small as half a millimeter square, about the size of a tiny seed. On-board memory within the IC stores data, while the IC then transmits/receives information through the antenna to an external reader.

Passive tags receive all of their power from the external tag reader, allowing the tag to “wake up” and transmit data. Specifically, tags can be read-only (stored data can be read but not changed), read/write (stored data can be altered or rewritten), or a combination, in which some data is permanently stored while other memory remains accessible for later encoding and updates. The vast number of passive RFID tags used in supply chain applications (such as asset management, inventory monitoring, access control and item-level tracking) comply with the UHF Gen 2 standard developed by EPCglobal. Passive tags use Electronic Product Code™ technology, which enables users to accurately identify multiple items at distances not possible with earlier generations of RFID tags. For more information about the Gen 2 standard, visit www.gs1.org/epcglobal.

A passive RFID tag is capable of transmitting a unique serial number anywhere from five to 30 feet in response to a query from a reading device. RFID readers connect through networks to computer systems that associate, or match, the RFID data to an internal database. The tag serial number acts as a pointer to the information about the product. UHF Gen 2 tags target applications that require low cost, long range, and limited or no security. Other RFID technologies like the MIFARE® group of proprietary technologies based upon the ISO/IEC 14443 Type A 13.56 MHz contactless smart card standard, offer strong encryption, higher per-unit costs and very short (inches) read ranges. MIFARE finds use in payment card and ticketing applications where secure data transactions are required. The U.S. government’s electronic passport program leverages both ISO/IEC 1444 and 7816, which also uses of a form of Public Key Infrastructure (PKI) that allows digital signatures to protect the data from tampering.

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