RFID Frequently Asked Questions

How does an RFID system work?

Information about an object is stored in a small chip that is connected to an antenna, and in some cases powered by a battery. This combination of chip and antenna is called an RFID tag. Another device, called a reader or interrogator, transmits a signal that searches for compatible RFID tags within its vicinity. When the tag's antenna picks up the signal, the tag activates and transmits the information stored on its chip to the reader. The reader then passes the tag's information to a backend computer system to complete the identification process, and if necessary, initiate workflows.

What is the size of RFID tags?

Tags range in size from a grain of rice to a brick, with a thickness from less than a millimeter to an inch or more. In most supply-chain applications, tags are typically small and flat, and are often sandwiched inside of an adhesive label.

What is the advantage of RFID over bar codes?

The largest difference between RFID and bar code technology is that bar codes are dependent on line-of-sight technology, while RFIDs are not. In other words, the bar code scanner has to directly "see"the bar code in order to read it, while RFID can be read at any angle, through packaging and even through shipping containers as long as the tag is within the distance range of a reader. RFID tags are also very durable as they can be encased in rigid, protective materials, while bar codes are susceptible to being torn, soiled, or otherwise damaged to a point of being unreadable.

Will RFID eventually replace bar codes?

RFID and bar codes will likely coexist for a long time. Currently, bar codes are considerably less expensive than RFID tags, and for certain tasks, they will likely continue to have advantages.

What is a "smart label?"

A small, very flat RFID tag that is embedded in an adhesive bar-code label. Smart labels allow a single sticker to accommodate both bar-code and RFID uses.

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 radio or television waves.

What is an Electronic Product Code (EPC)?

EPC is a unique number based on a global standard for product identification called a global trade item number (GTIN). This number uniquely identifies the manufacturer, brand, product type, unit of measure, etc., and can potentially identify items with serial numbers. The EPC can be associated with data in online databases to provide entities in the supply chain with extensive product and manufacturing information.

What are EPCglobal specifications?

An organization called EPCglobal (an affiliate of the Uniform Code Council and EAN International) has created different specifications for the frequency, encoding characteristics and other attributes of RFID tags. These specifications have become the standard in supply-chain applications. Different "classes" within these standards define memory capacities, frequencies and other characteristics. EPCglobal recently approved "Generation 2 tags" that have a single class that is being widely accepted among larger supply chain companies. These increase encryption capabilities and minimize interference problems caused by lighting and other environmental causes. For more information on these specifications, go to www.epcglobalinc.com.

What is the cost of an RFID tag?

Depending on the type, the usage and the quantity produced, tags currently cost from 20 cents each to several dollars. In supply-chain applications where smart labels are required, the cost per tag is typically between 40 and 50 cents.

How do I know which frequency is right for my RFID application?

Different frequencies have different characteristics that make them more useful depending on the application. In supply-chain applications in the United States, most passive RFID tags operate in two frequency bands: high frequency (HF) at 13.56 MHz, and ultrahigh frequency (UHF) from 860 to 960 MHz. See above, "What are EPCglobal specifications?" For standards in your industry, contact your trade organization or visit www.aimglobal.org.

Is it true that RFID doesn't work near metal and water?

No. It is true that radio waves bounce off metal and are absorbed by water at ultrahigh frequencies, which can make tracking metal products or those with high water content problematic. However, good system design and engineering can overcome this problem. 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 for tracking.

How much information can the RFID tag store?

Typically, RFID tags store only a few hundred bits of data. This accommodates basic identifying information about an item. In some RFID applications, however, the size can be as large as 1MB, especially if the tag is regularly recording additional information about the item during the life of the item. The reason the size of storage is typically low-especially in supply-chain applications-is that many systems interface to extensive universal product databases providing exhaustive, up to date information about the product at any point in time.

What is the detection range for RFID tags?

The read range of passive tags (tags without batteries) depends on many factors: the frequency of operation, the power of the reader, whether repeaters are used, and interference from metal, water or other RF devices. In general, low-frequency tags have a range of a foot or less. High frequency tags have a range of about three feet and UHF tags can be read from 10 to 20 feet. When longer ranges are needed, such as for tracking railway cars, active tags (tags that use batteries to boost the signal) have read ranges up to 300 feet or more.

Do individual items need to be tagged with RFID?

In supply-chain applications, it is usually not practical to use RFID tags for individual items unless the items are particularly valuable. Normally, RFID tags are only used at the pallet and case levels. It is likely that at some point tags will be used on most individual products, although it is estimated that it could be at least 5 years before the cost of tags becomes low enough to cost-justify individual item usage.

Will RFID lead to massive layoffs of workers?

RFID technology is a labor-saving technology so it's likely that some jobs will be affected as fewer workers will be needed to scan bar codes. But this transition won't happen quickly as it could take a decade or more before RFID is implemented on a wide enough scale to cause a sizable displacement of workers. Considering that many of the jobs that currently include the scanning of bar codes also include moving products and/or restocking shelves, most of these kinds of jobs will not likely be eliminated because of the use of RFID.

Will RFID become a means for unscrupulous characters to steal identities or for the government to impinge on civil rights?

As with other technologies, RFID can be used to benefit people or to harm them. There are certainly opportunities for abuse with RFID and its use will need to be tightly regulated and enforced to minimize this possibility.