RFID is in use all around us. If you have ever chipped your pet with an ID tag, used DARTtag or an Oyster Card you've used RFID. In addition, RFID is increasingly used with biometric technologies for security.
Unlike ubiquitous bar-code technology, RFID technology does not require contact or line of sight for communication. RFID data can be read through the human body, clothing and non-metallic materials.
Active or Passive or …
RFID tags are categorized as either active or passive. Active RFID tags are powered by an internal battery and are typically read/write, i.e. tag data can be rewritten and/or modified. An active tag's memory size varies according to application requirements; some systems operate with up to 1MB of memory. In a typical read/write RFID work-in-process system, a tag might give a machine a set of instructions, and the machine would then report its performance to the tag. This encoded data would then become part of the tagged part's history. The battery-supplied power of an active tag generally gives it a longer read range. The trade off is greater size, greater cost, and a limited operational life (which may yield a maximum of 10 years, depending upon operating temperatures and battery type).
Passive RFID tags operate without a separate external power source and obtain operating power generated from the reader. Passive tags are consequently much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. The trade off is that they have shorter read ranges than active tags and require a higher-powered reader. Read-only tags are typically passive and are programmed with a unique set of data (usually 32 to 128 bits) that cannot be modified. Read-only tags most often operate as a license plate into a database, in the same way as linear barcodes reference a database containing modifiable product-specific information.
Frequencies
RFID systems are also distinguished by their operating frequency. Low-frequency (125-134 KHz) systems have short reading ranges (< 20 cms) and low data rates. They are most commonly used in asset tracking, and animal identification applications. High-frequency (13.56 MHz) systems have a much faster data rate, enabling both longer data messages and the reading of multiple tags (so-called anti-collision), and a read range of 1 meter. Compared with LF tags, they are thinner, flexible and lower cost. HF tags are used asset control, security access, diamond and jewellery tracking and general logistics work. UHF systems (860-960 MHz) operate at country-specific frequencies. Their data rate is very fast, allowing anti-collision and the ability to select specific tags from a moving population. Read ranges of up to 7 meters can be achieved. UHF tags are used for such applications as general logistics, asset tracking and automated toll collection.
Advantages
The significant advantage of all types of RFID systems is the noncontact, non-line-of-sight nature of the technology. Tags can be read through a variety of substances such as snow, fog, ice, paint, crusted grime, and other visually and environmentally challenging conditions, where barcodes or other optically read technologies would be useless. RFID tags can also be read in challenging circumstances at remarkable speeds, in most cases responding in less than 100 milliseconds. The read/write capability of an active RFID system is also a significant advantage in interactive applications such as work-in-process or maintenance tracking. Though it is a costlier technology (compared with barcode), RFID has become indispensable for a wide range of automated data collection and identification applications that would not be possible otherwise.
Developments in RFID technology continue to yield larger memory capacities, wider reading ranges, and faster processing. It is highly unlikely that the technology will ultimately replace barcode — even with the inevitable reduction in raw materials coupled with economies of scale, the integrated circuit in an RF tag will never be as cost-effective as a barcode label. However, RFID will continue to grow in its established niches where barcode or other optical technologies are not effective. If some standards commonality is achieved - whereby RFID equipment from different manufacturers can be used interchangeably - the market will very likely grow exponentially.