RFID

What is RFID?
RFID Stands for Radio Frequency Identification. The technology itself has been around for decades, but only recently has it attracted a great deal of attention. Older tags (see “What is a tag?”) were very large, required batteries, and were only practical for a few applications, such as keeping track of livestock.

RFID does not require line-of-sight. Radio frequencies are used to communicate between the tag and reader. This means that an item can contain its label on the inside, so it doesn’t get damaged in shipping or handling.
 

There are a number of frequencies that RFID operates at, with each having its own advantages and disadvantages.
 

What is a tag?
A tag is a small electronic device that will transmit information upon request. Tags come in many shapes, sizes, and ranges. Tags can be built that are as small as the head of a pin, as flat as a sheet of paper, or even as a small disc that withstands extreme temperatures.

For high frequency tags, the size of the tag determines the distance the tag can be read from. A tag that is as small as the head of a pin may have a range of less than an inch, while a tag that is the size of a credit card has a range of about 5-6 inches. In cases where more range is needed, you can compensate for a smaller tag by increasing the size of the reader antenna or the signal power.
 

For ultra high frequency tags, the size of the tag is set. The distance the tag can be read from is determined by the power of the reader.
 

Tags can contain different amounts of information. Some tags can’t hold more than a serial number, while others can hold pages of information. Like range, you need a larger tag to store more information (although this size is negligable because the antenna is the majority of the size, not the space on the chip used for memory).
 

Tags also come in a wide range of costs. The cheapest tags have a short range, and don’t store anything more than a serial number. These tags cost under a dollar. Tags that store more information and have a larger range cost over a dollar. The price on tags is dropping constantly, and it is only a matter of time before it becomes cheap enough to tag anything.

What can RFID be used for?
Any application where inventory, organization, tracking, labeling, or routing is used has a potential for RFID use.

Taking an inventory becomes simple with RFID. Instead of having to handle each item, the user simply runs a scanner by the items that need to be inventoried, or moves the item past a scanner. The process can become even more automated by adding shelves that can tell what products are on them, removing the need for someone to take inventory. In warehouses, stations can be set up to scan and identify all the tags near them.

Organizing and labeling items can be made simpler by storing information about the item itself on the tag. Need to organize product by date built? Simply include that information on the tag.

Tracking and routing items becomes simpler—you can tell when an item passes through a door, which box an item is in, where it came from, and where it is supposed to go.
 

What are the differences between frequencies?

There are a large number of differences between the frequencies. In order to clear up confusion, we have created a chart to help companies decide which frequency is best for them.
 

Can RFID replace Bar Codes?
Most applications that use bar codes can be replaced with RFID. However, don’t expect every product in your grocery store to use them anytime soon—RFID tags are more expensive than printing a barcode, so their use will be limited to products that have an additional benefit from using them. To continue the grocery store example, you might see RFID on dairy products first in order to keep track of expiration dates.

The cost of RFID tags can be offset by its many advantages over barcodes. RFID tags can store more information, and is more durable than a barcode. In addition, you don’t need to keep an RFID tag on the outside of the item being scanned. RFID tags can contain unique serial numbers, which can be used to track individual items.

How does RFID work?

In this simple example, the RFID reader sends out a signal to the tag, which then transmits its information back to the reader. A reader can then do whatever it wants with the information, but in general it sends the information to a computer for processing.

What about privacy?
Recently, there’s been some concern with privacy. Benetton(TM) had planned to embed RFID chips into their clothing line for inventory tracking and theft prevention. Because each of these tags contain unique information, the theory is that a person could be tracked by reading the tags in their clothes.

Fortunately, RFID is impractical for tracking people using these tags. These are High Frequency tags. As mentioned before, range is determined both by tag size and reader size. In order to effectively track people, it would be necessary to read their tag from a considerable distance. The tags that can be embedded in clothes are small, and a huge reader would be required to read information from more than a few inches away.

An additional measure to ensure privacy is being implemented in the latest tags that are being released. These tags have a “Self Destruct” command that can be triggered when the device leaves possession of the person tracking the information. For example, a tag embedded in a shirt could be deactivated at the time of purchase.

What are active and passive tags?
Active tags contain their own power source, like a battery, while passive tags get their power from a reader. Active tags will typically have a larger communication range and can perform tasks when the reader is not present. Active tags do have a downside: They are physically larger, more expensive and require maintenance to replace or recharge their battery. Passive tags do not contain a power source, so they can be smaller, less expensive, and no maintenance is needed.

Is there a standard for tags?
 

The ISO 15693 standard was created for 13.56Mhz (HF) RFID tags and reader electronics. Tags that adhere to the ISO 15693 standard are the most common type of RFID tag currently on the market.
 

Standards for UHF tags exist, but aren't solidified.
 

There were many proprietary RFID tags that have been developed for specific market niches before an ISO standard was created. RFID tags that are developed and produced today are typically based on an ISO standard. New standards for other frequencies and applications are being created to facilitate the growth of the RFID market.