RFID Analyst

It is popularly believed that HF (13.56 MHz) RFID is limited to one meter range. However, there are many reasons to seek longer range at HF and it has even been available and in use for some time. The reasons for not using UHF, popularly portrayed as "the only way to go" for longer range with a passive tag, include fear of heating and molecule damage to drugs in healthcare and the effect of water and metal that can make UHF tags very short range in certain circumstances. Icelandic Fisheries successfully trialled HF for wet fish in pallets and cases because UHF did not work but range was only one meter with the usual credit card sized HF label. More would have been welcome.

 

At Metro, the world's third largest supermarket chain, they want to tag at item level using one frequency and one standard system if possible. For short range smart shelving, HF seems best because of the small size of the tag, so it fits easily on even the smallest container such as drugs. Also valuable is the fact that that the range is controlled (you know exactly what range you are achieving) and there is therefore no problem distinguishing one item from another. A UHF label may have long or short range depending on what is near to it at the time so it may be looking at the wrong thing. UHF labels have been too big for small items.

 

However, in any attempt to standardise on HF for item level tagging, the problem lies with large items such as apparel, where most practitioners in Japan, the UK and US see UHF as best because there is no water and little metal to worry about and at two meters range the UHF tags have been much smaller than HF tags (the opposite of the situation with short range tags) and potentially cheaper, or so it is argued, because the antenna on the tag can be cruder and of poorer conductivity and still work well.

 

There are even those who argue that the total cost of ownership can be lower with an HF system working at, say two meters. For example, there are no royalties to pay to Intermec and ten times as many HF tags have been made, giving economies of scale. (However, the volume story is changing fast in favour of UHF). More importantly, UHF can give interference between interrogators and it is only approved in Europe for narrow bandwidth and low power, restricting its range to one meter or so, and then only if water and metal are not causing problems. For that reason alone, although some 15 million RFID air baggage tags were sold in 2005 and 60 million will be sold in 2006, almost none will appear in Europe. That is leading some European retailers and airports to look at HF. Indeed, Airport World recently reported that Symbol Technologies had achieved a satisfactory 2 to 3 meters range with air baggage tags working at HF in Europe.

The inaugural Active RFID Summit hosted by IDTechEx was attended by 150 delegates from nine countries, a turnout greater than anticipated. The event looked at the technologies and application of active RFID (tags with a battery) and how it is embracing other wireless technologies such as Wifi, Zigbee, Bluetooth, sensors and DSRC. Some of the latter technologies go beyond the traditional definition of active RFID, but nevertheless we include them because they now provide similar functions. As with passive RFID the choices of Active RFID are diverse - from the range of frequencies useable, read ranges achievable, shapes and sophistication. Delegates were highly inquisitive with much discussion.

 

A strong ROI case for Active RFID made throughout the event is that despite the high tag price compared to passive tags ($5 to $100 versus sub $0.50), if it is reused many times, the cost per use can be very low. For example, a $50 tag used 10,000 times on containers of expensive equipment has a cost per use of just 0.5 cent. Savi Technology, Axcess, IDTechEx, Siemens and others made the point well. IDTechEx note that many companies that have been selling Active RFID systems or hardware for a few years say the business is profitable. Presenters also covered how Active RFID does not necessarily replace another technology but often does something new - from car clickers (about half a billion active RFID tags have been used to date for this application for the entire auto industry) to real time location of people and things.

 

Major applications of Active RFID covered at the conference were the tracking of cargo, proof of tamper evidence on containers, long-range asset tracking, peer-to-peer networks for sensing, real time location of assets and people, and remote identification in difficult environments (such as high water and metal presence). Wavetrend, the lead sponsor of the event, covered their diverse range of Active RFID case studies including tagging artwork in galleries for security and fast audit to tagging beds in hospitals, whereby insurance companies could monitor the time patients were in hospital and check this with the consultants recorded fees. They found the consultants were overbilling.

KSW Microtec have developed a dual antenna ePC Class 1 Generation 1 and 2 inlay - known as the Taurus, as pictured.

It consists of two antennas. The smaller antenna connected to the silicon chip allows for optimal coding at short range, which can otherwise be a problem with today's UHF antennas which are usually designed to optimise long range. A second antenna provides long range read and write capabilities. The two antennas are not connected to each other, which offers another significant advantage - the long range antenna could be independently printed, such as on a case or product, and the chip connected to the short range antenna assembled elsewhere, and then attached at high speed. Because placement of the "inner" antenna does not have to be as precise as attaching a silicon chip or even a strap to an antenna, this could potentially be done very quickly - overcoming a major bottleneck issue today.