Conventional and Low Cost RFID
May 24, 2004
Nowadays Radio Frequency Identification (RFID) is a term used for any device that can be sensed at a distance by radio frequencies with few problems of obscuration or misorientation. The origins of the term lie in the invention of tags that reflect or transmit a radio-frequency signal. Now ones working below 300 Hz and those working above 300 MHz, such as microwave (GHz) tags are included. For example, one type of REMOSO chipless RFID tag works at only a few hertz (modulated on 2.45 GHz). Others work at a few hundred Hertz. Inkode chipless taggants operate at around 20-25 GHz. Higher frequencies such as visible and infrared devices are excluded as these systems have very different properties. For instance, they are frequently very sensitive to obscuration, heat or light or orientation.
We use the term 'tag' to describe any such small device: shapes vary from pendants to the shape of postage stamps, beads, nails, labels, wires and even printed surfaces and thin tabs and microwire, thinner than a human hair, that can be laminated inside a product during manufacture.
In the last few years, the term "low cost RFID" has begun to be used and this may seem an artificial distinction at first sight. However, low cost RFID tags, typically taken as those costing less than one dollar each (less than $5 for long range, say over three meters), are different from conventional tags in several important respects. These differences mean that low cost RFID tags can be applied in very different, new applications and interest very different groups of suppliers and end users. Most importantly, they are usually cheap enough to be disposable and thin enough to go in new locations, even inside sheets of paper in some cases, so they are usually called smart labels. They create new markets.
Some conventional RFID devices are being re-designed as smart labels that are a fraction of the size and price, road tolling labels being an example.
Almost all conventional RFID devices contain a transistor circuit employing at least one microchip. By contrast, the potential in low cost RFID is equally split between chip-based technologies and "chipless" tags. Chipless tags can still be interrogated through many obstructions and at different orientations and hold data. However, they are about ten times cheaper but more primitive in electronic performance than the best low-cost chip devices.