What on earth is? RFID

Imagine, if you will, a supermarket without queues; a retail paradise where you could conclude your weekly grocery shop by simply pushing your trolley through the checkout, pausing only to sign the payment slip.

No need to unload your goods onto the conveyor belt and no time wasted as the person on the checkout scans the barcode on each product before you grab them again to reload your trolley.

Better still, never again will you find your fingers drumming a ditty of impatience while customers ahead of you go through the same laborious process.

If this sounds a bit far-fetched then prepare yourself for a pleasant surprise. In just a few years, this situation is likely to be a reality, thanks to a technology known as radio frequency identification (RFID).

Perhaps even more surprisingly, RFID isn't a new idea; it's been around since the late sixties. RFID is an umbrella term for systems that use radio waves to identify items bearing suitably equipped tags.

At its simplest, an RFID system uses an antenna to send out waves of electromagnetic pulses. These in turn prompt any in-range RFID tags to respond by beaming back the information they contain.

All technologies take time to mature and it's only recently that RFID has developed to the point where it's cheap enough to be a viable replacement for the humble barcode.

Advanced manufacturing techniques have seen the cost of basic RFID tags fall to just a few pence, meaning that retailers will soon be able to afford to affix them to almost any product.

It's not just shop shelves where you'll find RFID technology popping up. Many modern vehicles are fitted with an engine immobiliser, which calls on RFID technology, while many business premises have imposed office access controls based on RFID-bearing 'smart' cards.

On an even grander level, industrial strength versions of RFID are being installed on toll roads worldwide.

The science
The driving force behind retailers' burgeoning interest in the technology is the development of low-cost RFID transponders, little adhesive tags that combine a microchip with a coiled antenna and, in some cases, a minuscule battery.

RFID tags fitted with power cells are known as 'active' and those without power cells are called 'passive'.

The interrogator (reader) sends continuous electromagnetic pulses that, depending on the application, may extend from the transmitter just a few centimetres (for passive tags) or several metres (for active tags).

Either way, when an RFID tag passes through this magnetic field, an inductive coupling is formed, enlivening the microchip and setting in motion the identification process.

RFID systems work in one of three frequency ranges. The lowest, 100-500KHz, is cheap to install and operate and is designed for short-range applications, such as stock control or the arming of your car's immobiliser function, These tags will be passive.

The intermediate band occupies the 10-15MHz frequency and is designed for short- to medium-range interrogation, for example unlocking an office door with an RFID pass card. These tags will be active.

High-band RFID (also active), at 850-950MHz/2.4-5.8GHz, is designed for industrial use, such as gantry-mounted road toll collection systems.

The basics
As the technology's names implies, RFID relies on radio waves to detect and/or track tagged goods. It is essentially a two-piece system, comprising antenna-based 'interrogators' and RFID-bearing 'transponders'.

Considered in terms of the more familiar barcode, an RFID interrogator is akin to a barcode reader/scanner, while the transponder is similar to a barcode.

The key difference is that barcode technology is line-of-sight; in order to be read, the barcode must be presented against the electronic eye of the scanner.

But the information contained on an RFID transponder can be collected at a distance and without the need for direct contact with the goods bearing the tag.

The information that the RFID sends back to the interrogator can range from a simple code number up to a few dozen pages of information.

This capacity affords companies with RFID systems incredible versatility when it comes to tracking tagged goods.

A supermarket, for example, could study how often customers remove items from shelves for viewing as well as those they buy. A courier firm, meanwhile, could maintain a history of goods as they're moved around warehouses or shipped around the world.

Why you need to know about it
Over the coming years, it's likely that almost every product on shop shelves will bear an RFID tag. This is a shift that could revolutionise the way store checkouts operate.

Theoretically, items labelled with RFID tags can be scanned while remaining in the basket or trolley. Similarly, any products secreted in a coat pocket or bag can be 'seen' by an RFID scanner, improving store security.

Already in this country, Tesco is testing the application of RFID tags on certain high-value products in some stores.

The company has teamed up with razor manufacturer Gillette, which has affixed RFID stickers to its Mach 3 razor packets. This is apparently the item most favoured by shoplifters.

In the longer term, this means that shoppers will have to adapt to new procedures at checkouts, not to mention accepting that shopping will inevitably mean entering an envelope of electromagnetic activity. However, most RFID systems rely on low-power radio frequencies.