What is RFID and How Does RFID Work?

WHAT IS RFID?

RFID stands for "Radio Frequency Identification," a technology that captures digital data embedded in RFID tags or smart labels using radio waves via a reader. Similar to barcoding, RFID permits data from tags or labels to be recorded by a device that then stores this information in a database. However, RFID boasts several advantages over barcode-based asset tracking systems, the most significant being its ability to read tag data without needing direct line-of-sight. In contrast, barcodes must be linearly aligned with an optical scanner. If you're contemplating the adoption of an RFID solution, consider reaching out to the experts at AB&R® (American Barcode and RFID).

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HOW DOES RFID WORK?

RFID is classified as an Automatic Identification and Data Capture (AIDC) technology. AIDC methods automatically identify objects, collect data concerning them, and input this information directly into computer systems with minimal or no human input. RFID technologies utilize radio waves for this purpose. At a basic level, an RFID system includes three components: an RFID tag or smart label, an RFID reader, and an antenna. The RFID tags feature an integrated circuit and antenna, which transmit data to the RFID reader (also referred to as an interrogator). The reader transforms radio waves into a more usable data format. The information gathered from the tags is transferred via a communication interface to a host computer system, where the data is stored in a database for future analysis.

RFID TAGS AND SMART LABELS

An RFID tag consists of an integrated circuit, an antenna, and a protective material that houses these components and shields them from varied environmental conditions. The material used for protection is often determined by the application. For instance, employee ID badges with RFID tags are usually constructed from durable plastic, embedding the tag between the plastic layers. RFID tags are available in various shapes and sizes and can be either passive or active. Passive tags are more commonly used due to their smaller size and lower cost. They require the RFID reader to "power up" before data transmission. Conversely, active RFID tags incorporate a power supply (such as a battery), allowing constant data transmission. For a detailed comparison, refer to our article on Passive RFID Tags vs. Active RFID Tags.

Smart labels differ from RFID tags as they combine RFID and barcode technologies. These are adhesive labels with embedded RFID inlays, which may also include barcodes and other printed information. Smart labels can be encoded and printed on-demand using desktop label printers, while programming RFID tags necessitates more specialized equipment.

RFID APPLICATIONS

RFID TECHNOLOGY IS EMPLOYED IN MANY INDUSTRIES TO PERFORM TASKS SUCH AS:

• Inventory management
• Asset tracking
• Personnel tracking
• Controlling access to restricted areas
• ID Badging
• Supply chain management
• Counterfeit prevention (e.g., in the pharmaceutical industry)

RFID APPLICATIONS

Despite being used since World War II, the demand for RFID technology is growing rapidly, influenced partly by mandates from the U.S. Department of Defense (DoD) and Walmart, which require suppliers to enable traceability through RFID.

Regardless of compliance requirements, applications currently using barcode technology are strong candidates for transitioning to RFID or a hybrid system. RFID provides numerous advantages over barcodes, particularly the capacity to retain significantly more data about an item. Moreover, RFID tags are less vulnerable to physical damages that can affect barcode labels, such as tearing or smudging.

With advancements from its inception during World War II, RFID technology has a promising future. Review the evolution of RFID.

For additional insight into how RFID functions and how to integrate this technology into your business, please read our RFID Basics.

The Beginner's Guide to How RFID Systems Work

What is RFID?

RFID, or Radio Frequency Identification, entails the wireless, non-contact transfer of data using radio frequencies to identify objects, animals, or humans. Typically, RFID systems comprise RFID readers, RFID tags, and antennas. Industries such as healthcare, retail, hospitality, and manufacturing frequently utilize RFID technology. Unlike barcodes, RFID is not restricted by line-of-sight. This guide offers an overview addressing typical questions regarding RFID, its meaning, its operation, and its applications.

How Does RFID Work?

Utilizing RFID tags enables users to identify and track inventory and assets automatically. RFID relies on radio waves transmitted from an RFID antenna to tags nearby. RFID readers enhance energy, blend it with data, and send this energy at specific frequencies to an antenna cable linked to the RFID antenna.

The unique identifier within each RFID tag allows unique identification of individual items, distinguishing otherwise identical objects.

RFID advances auto-ID technology, enabling tags to be read efficiently without line-of-sight and from distances surpassing 30 meters.

The technology's origins trace back to World War II when it was first used to identify aircraft. Ongoing improvements in technology reduce implementation costs, making RFID systems increasingly efficient and cost-effective. To learn more about enhancements within RFID technology, check out our article - RFID Failed You in the Past? It May Have Improved More Than You Think.

What is RFID Used For?

The scope of RFID applications is broad, from inventory tracking to supply chain management, and is often tailored to specific industries or companies. RFID's edge lies in its ability to uniquely identify items quickly and effectively, especially in scenarios where traditional systems may fall short.

Types of RFID Frequencies

Understanding RFID technology requires knowledge of the three primary frequency ranges available for RFID transmissions: Low Frequency (LF), High Frequency (HF), and Ultra-High Frequency (UHF).

Low Frequency

• General Frequency Range: 30 - 300 kHz
• Primary Frequency Range: 125 - 134 kHz
• LF RFID Read Range: Contact - 10 Centimeters
• Average Cost Per LF RFID Tag: $0.75 - $5.00
• Applications: Animal Tracking, Access Control, Car Key-Fob, Applications with High Volumes of Liquids and Metals
• Pros: Functions effectively near liquids and metals, adheres to global standards
• Cons: Very short read range, limited memory capacity, low data transmission rate, high production costs

High Frequency

• Primary Frequency Range: 13.56 MHz
• HF RFID Read Range: Near Contact - 30 Centimeters
• Average Cost Per HF RFID Tag: $0.20 - $10.00
• Applications: DVD Kiosks, Library Books, Personal ID Cards, Poker/Gaming Chips, NFC Applications
• Pros: NFC global protocols, larger memory options, compliance with global standards
• Cons: Short read range, low data transmission rate

Ultra-High Frequency

• General Frequency Range: 300 - MHz
• Primary Frequency Ranges: 433 MHz, 860 - 960 MHz

Within Ultra High Frequency, there are two categories: Active RFID and Passive RFID.

Ultra-High Frequency: What are the Differences between Passive vs. Active RFID?

What is Active RFID?

• Primary Frequency Range: 433 MHz, can also use 2.45 GHz (under Extremely High-Frequency Range)
• Active RFID Read Range: 30 - 100+ Meters
• Average Cost Per Active RFID Tag: $15.00 - $50.00
• Applications: Vehicle Tracking, Auto Manufacturing, Mining, Construction, Asset Tracking, Cargo Container Tracking
• Pros: Long read range, reduced infrastructure cost (compared to Passive RFID), large memory capacity, high data transmission rates
• Cons: Higher costs per tag, shipping restrictions (due to batteries), complex software may be needed, high interference from metals and liquids, limited global standards

What is Passive RFID?

Passive RFID Focus

Primary Subsets of Passive RFID

The UHF Passive RFID range of 860 - 960 MHz is recognized as the global standard; however, its late adoption has led to the range dividing into subsets—865 - 868 MHz and 902 - 928 MHz. Depending on the manufacturer and geographic region, RFID tags and equipment can operate within either subset or the overall global range.

865 - 868 MHz - ETSI

The European Telecommunications Standards Institute (ETSI) governs communication standards in Europe, only permitting RFID equipment and tags to operate within the 865 - 868 MHz range. The intent is to allocate other communication types within the broader 860 - 960 MHz range.

ETSI standards may be referred to as either ETSI or EU denoting Europe.

902 - 928 MHz - FCC

The Federal Communications Commission (FCC) defines standards for electromagnetic communication in the United States, permitting RFID operation exclusively between 902 - 928 MHz, as other communications are distributed among larger frequency ranges.

RFID equipment or tags that are FCC certified or use the North American Frequency Range (NA) can be utilized throughout North America.

Other Radio Frequencies

Countries have either adopted ETSI or FCC standards or established their own standards within subsets of the frequency range. For example, Argentina adheres to the FCC range of 902 - 928 MHz, while Armenia uses its band of 865.6 - 867.6 MHz within the ETSI range.

In addition to frequency ranges, countries often regulate factors such as radiated power (ERP or EIRP). Some regions impose stricter regulations regarding RFID use, specify "frequency hopping," or mandate licenses for RFID usage. For regional regulations, refer to How to Conform to Regional Regulations when using RFID.

What is in an RFID System?

The structural components of RFID systems can vary but traditionally comprise four basic elements:

• Readers
• Antennas
• Tags
• Cables

Integrated or mobile RFID readers combine the components of the reader, antenna, and cabling into a single device, contributing to simplicity.

The simplest systems use a mobile handheld RFID reader (with an integrated antenna) along with RFID tags, while more complex configurations might include multi-port readers, antenna hubs, GPIO boxes, additional functional devices (e.g., stack lights), multiple antennas and cables, RFID tags, and a comprehensive software setup.

What is an RFID Tag?

In its simplest form, an RFID tag consists of two parts: an antenna for signal transmission and reception and an RFID chip (or integrated circuit, IC) that stores the tag's ID and relevant information. RFID tags are affixed to items for tracking via RFID readers and antenna combinations.

RFID tags transmit data about an item (contained within the RFID chip) wirelessly through radio waves to the connected antenna/reader. Typically, RFID tags do not have batteries (unless specified as Active or BAP tags); they acquire energy from the radio waves emitted by the reader. When the RFID tag receives the signal, the internal antenna channels the energy to the chip, activating it. The chip modulates energy with the necessary information and transmits it back to the reader.

Each RFID chip features four memory banks: EPC (Electronic Product Code), TID (Tag Identifier), User, and Reserved. Each memory bank provides distinct information pertaining either to the tagged item or the tag itself. While the EPC and User banks can be programmed with unique identification information, the TID bank is fixed, housing the tag's information, including its unique identifier. The Reserved memory bank serves specialized operations such as tag locking or expanding EPC capacity.

Many RFID tags are available in different shapes and sizes, designed to meet specific requirements regarding environments, surface materials, and applications. Selecting the appropriate tag for a particular application is critical for optimal performance. To learn about ideal tag selection and testing procedures, check our webinar - How to Select an RFID Tag, and our article, The Importance of Testing RFID Solutions.

For more information on RFID tags, refer to our comprehensive guide - A Guide to UHF RFID Tags.

Types of RFID Tags

Given the diversity of RFID applications, numerous types of RFID tags and categorization methods exist. A common classification distinguishes between inlays and hard tags. Inlays, generally priced between $0.09 - $1.75, are more affordable, whereas hard tags, noted for durability and weather resistance, range from $1.00 - $20.00.

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Form Factors: Inlay, Label, Card, Badge, Hard Tag

Frequency Types: LF, NFC, HF, UHF Passive (902 - 928 MHz, 865 - 868 MHz, or 865 - 960 MHz), BAP, Active

Environmental Considerations: Water-resistant, Rugged, Temperature resistant, Chemical resistant

Customization: Shape, Size, Text, Encoding

Specific Applications: Laundry Tags, Sensor Tags, Embedded Tags, Autoclavable Tags, Vehicle Tags, High Memory Tags

Material Compatibility: Metal-mount tags, Glass-mount tags, Liquid-filled item tags

How much do RFID Tags Cost?

The cost of tags generally depends on their type and quantity ordered. Inlays usually fall within the range of $0.09 to $1.75, while hard tags vary from $1.00 to $20.00. Tags requiring higher customization or specialization frequently cost more compared to off-the-shelf tags. For example, tags needing larger memory than the standard 96 - 128 bits may necessitate different ICs, leading to increased costs.

How to Select an RFID Tag

• What surface are you tagging? Is it metal, plastic, wood, etc.?
• What is your desired read range?
• Are there any size limitations (e.g., the tag must not exceed specific dimensions)?
• Consider any extreme environmental conditions—heat, cold, moisture, impact, etc.
• What will be the method of attachment (adhesive, epoxy, rivets/screws, cable ties, etc.)?
• Thorough testing of a variety of tags in your specific environment is crucial for optimal selection. Customized RFID tag sample packs can help identify the best tags for your needs.

For a comprehensive list of criteria for selecting RFID tags, consult our RFID Buyer’s Guide.

What is an RFID Reader?

An RFID reader serves as the system's "brain," making it essential for RFID functionality. Often referred to as interrogators, these devices transmit and receive radio waves to communicate with RFID tags. Readers can be classified into three types based on mobility: Fixed RFID Readers, Mobile RFID Readers, and USB Readers.

Fixed readers remain stationary and are typically installed on walls, desks, portals, or similar locations. They often incorporate external antenna ports that support one to up to eight antennas. Some models, combined with multiplexers, can connect to as many as 64 antennas, depending on the required coverage area. For instance, applications like file check-ins may only need a single antenna, whereas larger coverage zones, as seen in race timing applications, typically entail several antennas.

Mobile RFID readers are handheld devices that provide flexibility when reading RFID tags while maintaining communication with a host computer or smart device. Most mobile devices are cordless, relying on batteries and use Wi-Fi or Bluetooth for data transfer. Mobile RFID readers are split into two main categories: those featuring onboard computers (Mobile Computing Devices) and those that leverage Bluetooth or auxiliary connections to smart devices (Sleds).

An integrated RFID reader combines a reader and antenna, eliminating the need for an external antenna connection. Designed for aesthetic appeal, integrated readers are suited for indoor applications without high tag traffic.

Unique to RFID systems, USB readers offer portability while remaining tethered to a computer. They're preferred for desktop applications and for reading and writing individual RFID tags.

To learn more about RFID Readers, refer to our introductory guide - An Intro to RFID Readers: Basic Options and Features.

Types of RFID Readers

Readers are often classified based on mobility, but distinctions can also be made regarding connectivity, utilities, features, processing abilities, and power options.

• Frequency Range - US/FCC: 902 - 928 MHz, EU/ETSI: 865 - 868 MHz
• Mobility - Fixed, Mobile, and USB Readers
• Connectivity - Wi-Fi, Bluetooth, LAN, Serial, USB, Auxiliary Ports
• Utilities - HDMI, GPS, USB, Camera, GPIO, 1D/2D Barcode, Cellular Capabilities
• Processing - Onboard or No Onboard Processing
• Power Options - Adapter, PoE, Battery, Vehicle, USB
• Antenna Ports - None, 1-Port, 2-Port, 4-Port, 8-Port, 16-Port

How much do RFID Readers Cost?

RFID readers typically represent the most expensive component of an RFID system, with costs ranging from $500 to over $3,000, depending on features and capabilities. USB readers generally range from $500 to $600 and have limited read ranges suited for desktop applications. Handheld and fixed readers can also vary widely in price, contingent upon the offered functionalities.

How to Choose an RFID Reader

• What read range is necessary for your application?
• Are there environmental considerations (extremes of heat, cold, moisture, impact, etc.)?
• Will the reader need to be connected to a network?
• Where will the reader be installed? Fixed location or on a vehicle?
• Does the reader require mobility?
• How many read points/zones are necessary?
• What's the expected volume of simultaneously read tags?
• What is the anticipated speed of tag movement through the read zone?

For an extensive list of considerations when selecting an RFID reader, check our RFID Buyer’s Guide - https://www.atlasrfidstore.com/a-guide-to-buying-rfid-tags-equipment/.

What is an RFID Antenna?

RFID antennas are critical components in RFID systems, transforming the RFID reader's signal into RF waves recognizable by RFID tags. Without antennas, whether embedded in readers or external, RFID readers cannot adequately transmit or receive signals to tags.

Unlike RFID readers, RFID antennas are often described as "dumb devices" because they cannot independently power on or store energy and lack computing power. When an RFID reader transmits its energy, the antenna creates an RF field, and consequently, an RF signal is sent to surrounding tags. The antenna's efficiency in directing waves is referred to as gain; in short, higher gain equates to more powerful and expansive RF fields.

Antennas are typically categorized by how they transmit RF waves, identified by their polarity. Linearly polarized RFID antennas emit RF waves in a horizontal or vertical plane, while circularly polarized antennas project RF waves in a rotating manner, enhancing flexibility for reading tags in various orientations.

Linearly-Polarized Antennas

These antennas emit RF waves either horizontally or vertically. The orientation of the RF field can significantly influence a system's read range. To optimize read range, ensure that the antenna's polarity aligns with that of the RFID tag. If mismatched, a vertical antenna paired with a horizontal tag, for example, results in reduced read distance. Determining polarity is generally carried out during setup, as adjustments can be made easily; tags or antennas can be rotated to align.

For more insights on antenna polarization, see our article - Circular Polarization vs. Linear Polarization: Which is the Right RFID Antenna?

Circularly-Polarized Antennas

These antennas transmit RF waves that alternate between horizontal and vertical planes, providing flexibility in reading tags from multiple angles. However, energy is shared between two planes, meaning circularly polarized antennas typically have a shorter read range than similarly capable linear ones.

For further understanding of RFID antennas, refer to our article - 9 Tactics For Choosing an RFID Antenna.

Types of Antennas

RFID antennas can be classified based on various characteristics, helping to determine the most suitable option for specific requirements. Common categorizations include polarity (circular vs. linear) and ruggedness (indoor vs. outdoor).

• Frequency Range - US/FCC: 902 - 928 MHz, EU/ETSI: 865 - 868 MHz, Global: 860 - 960 MHz
• Polarity - Circular, Linear
• Ruggedness - Indoor IP Rated, Outdoor IP Rated
• Read Range - Proximity (Near-Field), Far-Field
• Mounting Types - Shelf Antenna, Ground Antenna, Panel Antenna, Portal Antenna

How much do RFID Antennas Cost?

RFID antennas typically range from $50 to $300 each. However, specialized antennas designed for specific applications (e.g., race timing) tend to be more costly, as they require greater durability and performance under high traffic. Investing in specialized antennas can significantly enhance application efficacy.

Selecting an RFID Antenna

• What is your required read range?
• Can you consistently control the tag's orientation relative to the antenna's position in your application?
• Are there significant environmental factors to assess (excessive heat, cold, moisture, impact, etc.)?
• Will the antenna be positioned indoors or outdoors?
• Are there any size restrictions (e.g., maximum dimensions for the antenna)?

For a complete list of questions for selecting an RFID antenna, see our RFID Buyer’s Guide - https://www.atlasrfidstore.com/a-guide-to-buying-rfid-tags-equipment/.

RFID Facts and Frequently Asked Questions

What is RFID's Return on Investment (ROI)?

Determining the value of deploying any new system requires addressing critical questions regarding prospective returns. Evaluating fixed and recurring costs, along with labor-associated switching expenses, is essential before implementing a new system.

Before launching an RFID solution, both application feasibility and cost feasibility need assessment.

What is RFID Application Feasibility?

Application feasibility assesses if RFID is suitable for a specific use case. Like all technologies, RFID has its limitations. Factors like environmental challenges, read range constraints, and the materials of assets can significantly influence the effectiveness of an RFID system. The process for assessing feasibility should initiate with project scoping and environment evaluation, followed by determining the appropriateness of RFID (or alternative technologies). Some applications may require more advanced features such as real-time tracking achievable through a Real-Time Location System (RTLS), which can incorporate RFID technology. Discover more about RTLS in our guide - What is RTLS? An Introduction to Real-Time Location Systems.

What is RFID Cost Feasibility?

Cost feasibility evaluates whether RFID system implementation is monetarily attainable. This involves considering potential ROI timing alongside current and prospective financial figures to estimate return timelines. RFID systems may entail substantial costs due to initial investments for testing and various equipment types, which could yield sunk costs if the technology isn't successful. After testing, deployment expenses follow. Only after successful implementation can one anticipate returns.

What are the Fixed vs. Recurring Costs of RFID Systems?

Classifying costs as fixed (initial) or recurring helps clarify anticipated operating costs and ROI.

Fixed Costs

Fixed costs encompass one-time outlays associated with setup. In the context of RFID deployment, fixed expenses typically pertain to hardware such as readers, antennas, and cables necessary for the system's establishment. Fixed costs signify that items may require purchase again over time, particularly when expanding existing systems. RFID tags count as fixed expenses when reused, such as access control RFID fobs distributed as necessary.

Recurring Costs

Recurring costs arise from items that are used once and subsequently discarded or consumed. RFID inlays or labels represent typical recurring expenses in an RFID system due to their affordability and common single-use nature. If an RFID printer is involved, printer ribbons also qualify as recurring costs. Additionally, software licenses renewing annually or employing a SaaS approach constitute recurring expenses.

Up Next

This guide provides foundational RFID knowledge yet merely scratches the surface regarding RFID technology implementation. Fortunately, multiple resources exist for further learning:

RFID Insider: This blog aims to keep you updated and informed about the latest RFID industry developments, serving both seasoned experts and newcomers.

YouTube Channel: Explore tutorials, interviews, and discussions surrounding radio frequency identification across various industries.

eBooks & Resources: Many resources, including additional guides on RFID systems, applications, and deployment, are accessible in our RFID resources section.

For additional information or questions, please feel free to contact us.

For further details, kindly check out our UHF RFID Printer Module.