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Yet another technical hurdle in the development of small and efficient low-cost UHF transponders has been crossed by South African RFID tag manufacturer, TrolleyScan, whose simultaneous close-proximity tag-reading system also featured in the news recently (Dec. 5th, 2003).
The firm's new EcoTag product variation delivers a credit card-sized UHF (ultra-high frequency) transponder that needs less than 250 microwatts of RF (radio frequency) power to operate, while achieving an effective operating range of up to 9 metres.
According to TrolleyScan's managing director, Mike Marsh, the 'holy grail' of RFID (radio frequency identification) is to produce simple, small, yet efficient transponders that are easy to mass produce, and that offer a good operating range.
Key development
The technology for low power operation of transponders is one of the more important recent developments in passive UHF RFID. In the same way that recent developments in mobile telephony allow for smaller mobile telephones with longer battery life, the efficient use of RF power by transponders allows low power passive transponders to operate over long ranges, despite very low energising fields.
Printed antenna
TrolleyScan has produced, for commercial consumption, its latest transponder which is smaller than the common credit card in size, needs only 250 microwatts of radio energy to operate, where its antenna can be produced using simple manufacturing processes such as printing directly onto the packaging with a printing machine using conductive ink.
A typical efficient UHF antenna will be 160mm long. But market demand is for shorter antennae that are closer to the sizing of goods being labelled. Shortening a 160 millimetre antenna to 80 millimetres results in only 3% of the efficiency being left, and it is this impact that is of great concern to UHF RFID producers. The challenge is to increase efficiency in order to get greater coverage and range. Trolley Scan's 80mm by 33mm flat antenna recovers the lost efficiency as well as increasing the performance of the chip, allowing the firm's low power transponders to still work efficiently.
The credit card sized version is produced in a single plane and is ideal for production using conductive inks applied with a printing press. According to TrolleyScan, this is an important development because the volume application of RFID will mean the antennae need to be made directly on the packaging of each product. TrolleyScan has commenced commercial production, and its EcoTag technology is now protected by a series of patents granted in the US, Europe, and other countries.
Source: Trolley Scan (Pty) Ltd
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