A Technical RFID Primer

gManZboy writes "Roy Want, principal engineer at Intel Research, has a pretty meaty technical overview of RFID up at Queue. If you ever wondered how these little things actually work it's worth a read. For instance, I was intrigued to find out how the tags (which are generally battery-free) can absorb enough energy from RFID readers to then power up and transmit their own signal back to the reader."

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[chrisopherpace]

Bloody thing's getting slow here:

Just how do those little things work anyway?
Radio Frequency Identification

Many modern technologies give the impression they work by magic, particularly when they operate automatically and their mechanisms are invisible. A technology called RFID (radio frequency identification), which is relatively new to the mass market, has exactly this characteristic and for many people seems a lot like magic. RFID is an electronic tagging technology (see figure 1) that allows an object, place, or person to be automatically identified at a distance without a direct line-of-sight, using an electromagnetic challenge/response exchange. Typical applications include labeling products for rapid checkout at a point-of-sale terminal, inventory tracking, animal tagging, timing marathon runners, secure automobile keys, and access control for secure facilities.

Click for Figure

In fact, various forms of crude RFID have been used since World War II. In the 1960s the technology became more practical, but the applications since then have resulted in relatively small tag deployments in narrow high-value areas without much public visibility. Also, given a tag's small size and ability to be hidden or molded into the casing of a product, some people may have encountered RFID without realizing it was present.

In the last couple of years many RFID stories have appeared in the popular press. Why is RFID making a splash now, given that the idea is at least 40 years old? Most technologies have a window of opportunity for deployment, which is related to the scope of the problem it solves, the maturity of the technology, and the cost of deployment. On all three of these points the world has changed over the past 40 years. Inventory tracking is now necessary on an unprecedented scale to support growing consumer markets at low operating costs and to remain price competitive despite the relatively high labor cost in the developed countries. Furthermore, the components used to build the tags and tag readers have become more sophisticated. Today, they provide greater functionality, reading range, and speed of data transfer. As a result, they support the ability to accurately read a large number of co-located tags at the same time. Standards also play a role--an important new standard created by the former Auto-ID Center (whose work is now being carried forward by the not-for-profit EPCglobal) has recently brought together a number of influential organizations such as Wal-Mart, Tesco (UK), and the U.S. Department of Defense (DoD), all of which recognize the opportunity RFID brings to improve operational efficiencies.

Lastly, the ultimate incentive for deployment of a technology is cost. When the benefits and cost savings brought about by the technology are greater than the deployment cost, the time is right. Since tags would most often be attached to large inventories of relatively inexpensive products, the tags need to be inexpensive. Some analysts say a tag must cost less than 5 cents (others below 1 cent) for the technology to be truly competitive. By comparison, existing tagging technologies such as bar-code systems involve little more than the very low cost of printing lines on packaging. At present, RFID tags are in the 50-cent range for small quantities, a number that could be reduced to the target price if their use were to grow as expected.

Initially, commercial deployment is likely to focus on pallet- or crate-level tracking in a warehouse, and depending on its success, may lead to item-level tracking in the future. RFID could improve the efficiency of warehouse management considerably. RFID tags would allow crate identities to be checked at a distance when entering or leaving the building, whether or not the tag is directly visible. A bar code used in the same application could well be facing the wrong direction, making it impossible to scan automatically. Once RFID has proved beneficial and has been well established, economies of scale such as mass production s