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RFID FAQ
What is RFID?
Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. There are several methods of identification, but the most common is to store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna (the chip and the antenna together are called an RFID transponder or an RFID tag). The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be passed on to computers that can make use of it.

What is Automatic Identification?
Automatic identification, or auto ID for short, is the broad term given to a host of technologies that are used to help machines identify objects. Auto identification is often coupled with automatic data capture. That is, companies want to identify items, capture information about them and somehow get the data into a computer without having employees type it in. The aim of most auto-ID systems is to increase efficiency, reduce data entry errors, and free up staff to perform more value-added functions, such as providing customer service. There are a host of technologies that fall under the auto-ID umbrella. These include bar codes, smart cards, voice recognition, some biometric technologies (retinal scans, for instance), optical character recognition, and radio frequency identification (RFID).

How does an RFID system work?
An RFID system consists of a tag, which is made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from field created by the reader and uses it to power the microchip’s circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data.

Are there any health risks associated with RFID and radio waves?
RFID uses the low-end of the electromagnetic spectrum. The waves coming from readers are no more dangerous than the waves coming to your car radio.

Why is RFID better than using bar codes?
RFID is not necessarily "better" than bar codes. The two are different technologies and have different applications, which sometimes overlap. The big difference between the two is bar codes are line-of-sight technology. That is, a scanner has to "see" the bar code to read it, which means people usually have to orient the bar code towards a scanner for it to be read. Radio frequency identification, by contrast, doesn’t require line of sight. RFID tags can be read as long as they are within range of a reader. Bar codes have other shortcomings as well. If a label is ripped, soiled or falls off, there is no way to scan the item. And standard bar codes identify only the manufacturer and product, not the unique item. The bar code on one milk carton is the same as every other, making it impossible to identify which one might pass its expiration date first.

Will RFID replace bar codes?
Probably not. Bar codes are inexpensive and effective for certain tasks. It is likely that RFID and bar codes will coexist for many years.

Is RFID new?
RFID is a proven technology that's been around since at least the 1970s. Up to now, it's been too expensive and too limited to be practical for many commercial applications. But if tags can be made cheaply enough, they can solve many of the problems associated with bar codes. Radio waves travel through most non-metallic materials, so they can be embedded in packaging or encased in protective plastic for weather-proofing and greater durability. And tags have microchips that can store a unique serial number for every product manufactured around the world.

If RFID has been around so long and is so great, why aren’t all companies using it?
Many companies have invested in RFID systems to get the advantages they offer. These investments are usually made in closed-loop systems—that is, when a company is tracking goods that never leave its own control. That’s because all existing RFID systems use proprietary technology, which means that if company A puts an RFID tag on a product, it can’t be read by Company B unless they both use the same RFID system from the same vendor. But most companies don’t have closed-loop systems, and many of the benefits of tracking items come from tracking them as they move from one company to another and even one country to another.

Is the lack of standards the only thing that has prevented RFID from being more widely used?
Another problem is cost. RFID readers typically cost $1,000 or more. Companies would need thousands of readers to cover all their factories, warehouses and stores. RFID tags are also fairly expensive – 20 cents or more – which makes them impractical for identifying millions of items that cost only a few dollars (see below).

What is the difference between low-, high-, and ultra-high frequencies?
Just as your radio tunes in to different frequency to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low- (around 125 KHz), high- (13.56 MHz) and ultra-high frequency, or UHF (850-900 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequency, so you have to choose the right frequency for the right application.

How do I know which frequency is right for my application?
Different frequencies have different characteristics that make them more useful for different applications. For instance, low-frequency tags are cheaper than ultra high frequency (UHF) tags, use less power and are better able to penetrate non-metallic substances. They are ideal for scanning objects with high-water content, such as fruit, at close range. UHF frequencies typically offer better range and can transfer data faster. But they use more power and are less likely to pass through materials. And because they tend to be more "directed," they require a clear path between the tag and reader. UHF tags might be better for scanning boxes of goods as they pass through a bay door into a warehouse. It is probably best to work with a consultant, integrator or vendor that can help you choose the right frequency for your application.

Do all countries use the same low-, high and ultra-high frequencies?
Most countries have assigned the 125 kHz or 134 kHz area of the radio spectrum for low-frequency systems, and 13.56 MHz is used around the world for high-frequency systems. But UHF RFID systems have only been around since the mid-1990s and countries have not agreed on a single area of the UHF spectrum for RFID. Europe uses 868 MHz for UHF and the U.S. uses 915 MHz. Until recently, Japan did not allow any use of the UHF spectrum for RFID, but it is looking to open up the 960MHz area for RFID. Many other devices use the UHF spectrum, so it will take years for all governments to agree on a single UHF band for RFID. Government’s also regulate the power of the readers to limit interference with other devices. Some groups, such as the Global Commerce Initiative, are trying to encourage governments to agree on frequencies and output. Tag and reader makers are also trying to develop systems that can work at more than one frequency, to get around the problem.

I’ve heard that RFID doesn’t work around metal and water. Does that mean I can’t use it to track cans or liquid products?
No. Radio waves bounce off metal and are absorbed by water at ultra-high frequencies. That makes tracking metal products or those with high water content problematic, but good system design and engineering can overcome this shortcoming. Low- and high-frequency tags work better on products with water and metal. In fact, there are applications in which low-frequency RFID tags are actually embedded in metal auto parts to track them.

What’s the difference between passive and active tags?
Active RFID tags have a battery, which is used to run the microchip's circuitry and to broadcast a signal to a reader (the way a cell phone transmits signals to a base station). Passive tags have no battery. Instead, they draw power from the reader, which sends out electromagnetic waves that induce a current in the tag's antenna. Semi-passive tags use a battery to run the chip's circuitry, but communicate by drawing power from the reader. Active and semi-passive tags are useful for tracking high-value goods that need to be scanned over long ranges, such as railway cars on a track, but they cost a dollar or more, making them too expensive to put on low-cost items. Companies are focusing on passive UHF tags, which cost under a 50 cents today in volumes of 1 million tags or more. Their read range isn't as far -- typically less than 20 feet vs. 100 feet or more for active tags -- but they are far less expensive than active tags and can be disposed of with the product packaging.

What is an Electronic Product Code?
The Electronic Product Code, or RFID, was developed by the Auto-ID Center as a successor to the bar code. It is a numbering scheme that will be used to identify products as they move through the global supply chain. For more on EPC technology, see Electronic Product Code FAQs.

How much information can the tag store?
It depends on the vendor and the application, but typically a tag would carry no more than 2KB of data—enough to store some basic information about the item it is on. Companies are now looking at using a simple "license plate" tag that contains only a 96-bit serial number. The simple tags are cheaper to manufacture and are more useful for applications where the tag will be disposed of with the product packaging.

What’s the difference between read-only and read-write tags?
Microchips in RFID tags can be read-write or read-only. With read-write chips, you can add information to the tag or write over existing information when the tag is within range of a reader, or interrogator. Read-write tags usually have a serial number that can't be written over. Additional blocks of data can be used to store additional information about the items the tag is attached to. Some read-only microchips have information stored on them during the manufacturing process. The information on such chips can never been changed. Other tags can have a serial number written to it once and then that information can't be overwritten later.

What is reader collision?
One problem encountered with RFID is the signal from one reader can interfere with the signal from another where coverage overlaps. This is called reader collision. One way to avoid the problem is to use a technique called time division multiple access, or TDMA. In simple terms, the readers are instructed to read at different times, rather than both trying to read at the same time. This ensures that they don't interfere with each other. But it means any RFID tag in an area where two readers overlap will be read twice. So the system has to be set up so that if one reader reads a tag another reader does not read it again.

What is tag collision?
Another problem readers have is reading a lot of chips in the same field. Tag collision occurs when more than one chip reflects back a signal at the same time, confusing the reader. Different vendors have developed different systems for having the tags respond to the reader one at a time. Since they can be read in milliseconds, it appears that all the tags are being read simultaneously.

What is the read range for a typical RFID tag?
The read range of passive tags (tags without batteries) depends on many factors: the frequency of operation, the power of the reader, interference from metal objects or other RF devices. In general, low-frequency tags are read from a foot or less. High frequency tags are read from about three feet and UHF tags are read from 10 to 20 feet. Where longer ranges are needed, such as for tracking railway cars, active tags use batteries to boost read ranges to 300 feet or more.

Are there any standards for RFID?
Yes. International standards have been adopted for some very specific applications, such as tracking animals. Many other standards initiatives are under way. The International Organization for Standardization (ISO) is working on standards for tracking goods in the supply chain using high-frequency tags (ISO 18000-3) and ultra-high frequency tags (ISO 18000-6). EPCglobal, a joint venture set up to commercialize Electronic Product Code technologies, has its own standards process, which was used to create bar code standards. EPCglobal intends to submit EPC protocols to ISO so that they can become international standards.

Who are the leading RFID vendors?
There are many different RFID vendors with different areas of expertise. RFID Journal has compiled a searchable database and director of vendors around the world.

What are some of the most common applications for RFID?
RFID is used for everything from tracking cows and pets to triggering equipment down oil wells. It may sound trite, but the applications are limited only by people’s imagination. The most common applications are tracking goods in the supply chain, reusable containers, high value tools and other assets, and parts moving to a manufacturing production line. RFID is also used for security (including controlling access to buildings and networks) and payment systems that let customers pay for items without using cash.

Are any companies using RFID today?
Yes. Thousands of companies around the world use RFID today to improve internal efficiencies.

I’ve heard RFID can be used with sensors. Is that true?
Yes. Some companies are combining RFID tags with sensors that detect and record temperature, movement, even radiation. One day, the same tags used to track items moving through the supply chain may also alert staff if they are not stored at the right temperature, if meat has gone bad, or even if someone has injected a biological agent into food.


What are intelligent software agents and how do they fit into RFID?
Software agents are basically autonomous applications that automate decision making by establishing a set of rules. For instance, if X happens, do Y. They are important to RFID because humans will be overwhelmed by the amount of data coming from RFID tags and the speed at which it comes (real-time in many cases). So agents will likely be used to automate routine decisions and alert employees when a situation requires their attention. Companies are working on an automated replenishment system in which software agents would make decisions when trends indicate a product will be out of stock.

What is "energy harvesting"?
Most passive RFID tags simply reflect back waves from the reader. Energy harvesting is a technique in which energy from the reader is gathered by the tagged, stored momentarily and transmitted back at a different frequency. This method may improve the performance of passive RFID tags dramatically.
RFID Basics

What is RFID?

RFID (Radio Frequency Identification) is a method of identifying unique items using radio waves. Typical RFID systems are made up of 2 major components: readers and tags. The reader, sometimes called the interrogator, sends and receives RF data to and from the tag via radio waves.


A reader may have multiple antennas that are responsible for sending and receiving the radio waves. The tag, or transponder, is made up of the microchip that stores the data, an antenna, and a carrier to which the chip and antenna are mounted.


Is All RFID Created Equal?

There are many different versions of RFID that operate at different radio frequencies. The choice of frequency is dependent on the requirements of the application.


Three primary frequency bands have been allocated for RFID use:


Low Frequency, 125 KHz – most commonly used for access control and asset

tracking. Short range, less susceptible to metal or water, higher material

cost. 1 – 10 tags allowed in the field, read range 0.5 – 1.5 feet.


High Frequency, 13.56 MHz - used where medium data rate and read ranges

are required. Faster communication and high security, data encryption

capabilities. Available as read/write chips with large memory cells,

microprocessor chips support multi-application functions. 1 – 50 tags

allowed in the field, read range 0.3 – 3.3 feet.


Ultra-High Frequency, 860 – 960 MHz (915 MHz in the USA) – offer the longest

read ranges – up to 30 feet and fast data transfer. Poor for liquid and

metal, low material cost. Right now 200 or less tags are allowed in the

field, but moving into 2006, EPC compliant Generation 2 chips will

support up to 400 tags in the reader field., read range 2 – 30 feet.


** This is the frequency band used in most supply chain applications –

case and pallet tags.

Glossary of Commonly Used Terms

A


Active Tag – An RFID tag that uses a battery to power its microchip and communicate with a reader. Active tags can transmit over the greatest distances (100+ feet). Typically they can cost $20.00 or more and are used to track high value goods like vehicles and large containers of merchandise.


Agile Reader – A reader that can read different types of RFID tags – either operating on different frequencies or different standards – class 1 & class 0 – in the same frequency.

Antenna – A device that converts radio frequency electric current to electromagnetic waves that are then radiated into space. Every wireless system has an antenna without it the RFID system will not work. Since the antenna is common to both transmit and receive it has the biggest impact on the systems performance.


Anti-Collision – A feature of RFID systems that enables a batch of tags to be read in one reader field by preventing the radio waves from interfering with one another. It also prevents individual tags from being read more than once.


Air Interface – refers to the portion of the system that uses radio waves or RF to invisibly transfer information from the tag to the reader and vice versa.


Automatic Data Capture (ADC) – Methods of collecting data and entering it directly into a computer system without human intervention. Automatic Identifications (Auto-ID) refers to any technology for capturing and processing data into a computer system without using a keyboard. Includes bar coding, RFID and voice recognition.


B


Bit- The smallest unit of digital information – A binary code – a single ‘0’ or ‘1’, where many different codes can be developed to represent pertinent information. A 96-bit EPC is a string of 96 zeros and ones.


Byte – 1 byte = 8 bits. One byte of memory is needed to generate an alpha character or digit. So bytes can be thought of in terms of characters.


C


Chip Based RFID – Refers to RFID tags that contain a integrated circuit and therefore can store a unique serial number or other information and transmit that information to a reader.


Collision –See Tag Collision


E


Electronic Article Surveillance Tags (EAS) – Single bit (either ‘on’ or ‘off’) electronic tags used to detect items for anti-theft purposes. EAS technology is similar to RFID in that it uses similar frequency bands. Also many of the 13.56 MHz RFID chips contain a built-in EAS function.


Electromagnetic Compatibility (EMC) - The ability of a technology or product to coexist in an environment with other electro-magnetic devices.


EPCglobal , Inc.– EPCglobal is a joint venture between EAN International and the Uniform Code Council, Inc it is a not-for-profit organization entrusted by industry to establish and support the Electronic Product Code (EPC) Network as the global standard for immediate, automatic, and accurate identification of any item in the supply chain of any company, in any industry, anywhere in the world. EPC Global’s objective is to drive global adoption of the EPCglobal Network. EPC is the next generation of product identification schemes. EPCglobal develops standards to support the use of RFID in today’s fast moving, information rich trading networks.


Electronic Product Code (EPC) - Is the next generation of product identification. The EPC is a simple compact, 64 bit or 96 bit “license plate” that uniquely identifies objects (items, cases, pallets, locations, etc.) in the supply chain. The EPC is built around a basic hierarchical idea that can be used to express a wide variety of different, existing numbering systems, like the EAN.UCC system keys, UID, VIN, and other numbering systems. Like many current numbering schemes used in commerce, the EPC is divided into numbers that identify the manufacturer and product type. The EPC, however, uses an extra set of digits, a serial number, to identify unique items. The EPC is the key to the information about the product it identifies that exits in the EPCglobal Network.


F


Frequency – refers to a band of operation for radio-based technologies. Frequencies allocated for RFID use exist in the low (125Khz), high (13.56 MHz), ultra-high (860 to 960 MHz) and microwave (2.45 Ghz) frequency bands. Each frequency has its own advantages and disadvantages such as read distance, tag size and resistance to electronic noise.


G


GTAG (Global Tag) – A standardization initiative of Uniform Code Council (UCC) and the European Article Numbering Association (EAN) for supply chain tracking applications using UHF RFID frequencies.


Serialized Global Trade Item Number (SGTIN) –,The Serialized Global Trade Item Number is a new identity type based on the EAN.UCC Global Trade Item Number (GTIN). A GTIN by itself does not represent a pure EPC identity because it does not uniquely identify a single physical object. Instead a GTIN identifies a particular class of object, such as a particular kind of product or SKU.


H


High-Frequency RFID (13.56 MHz) – RFID that uses 13.56 MHz radio frequency band. Features medium sized tags and relatively good reading distances. In the U.S. 13.56 MHz tags can be typically read at approximately 3 – 4 inches with a handheld reader and up to 3 feet with a portal reader. Both read only and read/write chips are available in this frequency. Two ISO Standards define RFID performance in this frequency, ISO 14443 for proximity applications such as contactless smart cards and ISO 15693 for proximity applications such as item and asset tracking.


I


Integrated Circuit (IC) – Another name for a microchip


Interrogator – See Reader


L


Line-of-Sight – Technology that requires an item to be “seen” to be automatically identified by a machine. Unlike bar codes and OCR technologies, RFID tags can be read “through” merchandise and most packaging with no line of sight required.


Low-Cost RFID – Typically refers to RFID tags that cost less than $1.00 with typically 3 feet of read range.


Low Frequency RFID (125 & 134 KHz) – Low frequency radio band allocated for RFID use. The main disadvantage of low frequency RFID is its cost and relatively slow data transfer as well as it inability to read many tags at the same time.


M


Multiple Tag Read/Write - Refers to the ability of RFID systems to read multiple tags at the same time. Reading and writing of multiple tags is achieved through the anti-collision feature programmed into the chip


Microwave RFID Frequency (2,450 MHz or 2.45 GHz) - A microwave frequency band allocated for RFID use. Typically microwave RFID technologies feature the smallest label footprint and long read distances. Typical applications include industrial asset tracking with long range reads and automated toll collection – toll lanes, and rail car tracking


P


Passive RFID Tag – An RFID tag that does not use a battery. Passive tags draw their power from the reader field. The reader transmits a low power radio signal through its antenna. The tag in turn receives it through its own antenna to power the integrated circuit (chip). Using the energy it gets from the signal, the tag will briefly converse with the reader for verification and the exchange of data. As a result, passive tags can transmit information over shorter distances (typically 10 feet or less) than active tags. They are considerably lower in cost ($0.30 or less) making them ideal for tracking lower cost items.


Perpetual Inventory – The ability to know one’s inventory position at any given time. RFID offers the promise of being able to perform automatic inventory counts.


R


Radio Frequency Identifications (RFID) - A method of identifying tagged items using radio waves. Radio waves do not require line of site and can pas through materials like cardboard and plastic but not metals and some liquids.


Read Range – The distance from which a reader can communicate with a tag. Several factors including frequency used, orientation of the tag, power of the reader and design of the antenna affect read range.


Reader – Also called an interrogator. The device that contains the “radiotronics” which trigger the transponder to respond. – the reader is a device that captures and processes tag data then passes the digital data to a computer system. The readers main functions are; supply power to passive tags, provide command data to tags, capture returned tag signals and process into a digital bit stream, output data to another output device or to a computer system, and write data to the tag.

Readers can be configured with antennas in many formats including handheld devices, portals or conveyor mounted.


Read Only Tags – Tags that contain data that cannot be changed. Read only chips are less expensive than read-write chips.


Read-Write Tags – RFID chips that can be read and written to multiple times. Read/Write tags can accept data at various points along the distribution cycle. This may include transaction data at the retail point of sale. They are typically more expensive than read only tags but offer more flexibility.


RFID Transponder – Another name for a RFID tag. Typically refers to a microchip that is attached to an antenna, which communicates with a reader via radio waves. RFID tags contain serial numbers that are permanently encoded, and which allow them to be uniquely identified. RFID tags vary widely in design. They may operate at one of several frequency bands, may be active or passive and may be read-only or read-write.


S


Savant – Distributed network software that manages and moves data related to Electronic Product Codes (EPC).


Smart Label – A label that contains an RFID chip and antenna. These labels can store information such as a unique serial number and communicate with a reader.


T


Tag – a device which is attached to the object to be identified and when appropriate radio signals are received transmits information as radio signals to a reader. Tags are specified according to their operating frequency, memory modes, memory size, type and packaging.


Tag Collision – Interference caused when more than one RFID tag sends back signals to the reader at the same time. The majority of RFID chips incorporate a anticollision function in their circuitry that allows many tags – up to 200 in the case of UHF tags - to be read simultaneously in the reader field.


Transponder – A contraction of the words transmit and respond. This is another name for an RFID Tag. A transponder consists of an RF integrated circuit, the antenna and the substrate. The transponder receives the power it requires to transmit & respond when it placed in energy field being transmitted by a RFID reader.


U


Ultra-High Frequency (UHF; 860 to 960 MHz) – Ultra-high frequency radio band allocated for RFID use. (902 to 928 MHz in the USA & 860 MHz in Europe) UHF RFID can send information faster and farther than high and low frequency tags. UHF RFID is gaining industry support as the bandwidth of choice for inventory tracking applications including pallets and cases. UHF RFID features larger tags and readers with the longest read distances (2-3 feet with handheld readers and more than 10 feet with portal readers).


W


WORM” Chip (Write Once Read Many) – The chips memory can be written to once and then becomes “Read Only” afterwards.