History of RFID tags

In 1945 Léon Theremin invented an espionage tool for the Soviet government. Even though this device was a passive covert listening device, not an identification tag, it has been attributed the first known device and a predecessor to RFID technology. The technology used in RFID has been around since the early 1920s according to one source (although the same source states that RFID systems have been around just since the late 1960s).
A similar technology, the IFF transponder, was invented by the British in 1939, and was routinely used by the allies in World War II to identify airplanes as friend
or foe.
Another early work exploring RFID is the landmark 1948 paper by Harry Stockman, titled "Communication by Means of Reflected Power" (Proceedings of the IRE, pp 1196-1204, October 1948). Stockman predicted that "...considerable research and development work has to be done before the remaining basic problems in reflected-power communication are solved, and before the field of useful applications is explored." It required thirty years of advances in many different fields before RFID became a reality.

Types of RFID tags

RFID tags can be active, semi-passive (=semi-active) or passive.
Passive RFID tags have no internal power supply. The minute electrical current induced in the antenna by the incoming radio frequency signal provides just enough power for the CMOS integrated circuit (IC) in the tag to power up and transmit a response. Most passive tags signal by backscattering the carrier signal from the reader. This means that the aerial (antenna) has to be designed to both collect power from the incoming signal and also to transmit the outbound backscatter signal. The response of a passive RFID tag is not just an ID number (GUID): tag chip can contain non-volatile EEPROM (Electrically Erasable Programmable Read-Only Memory) for storing data. Lack of an onboard power supply means that the device can be quite small: commercially available products exist that can be embedded under the skin. As of 2006, the smallest such devices measured 0.15 mm × 0.15 mm, and are thinner than a sheet of paper (7.5 microns); such devices are practically invisible. Passive tags have practical read distances ranging from about 2 mm (ISO 14443) up to about few metres (ISO 18000-6) depending on the chosen radio frequency. Due to their simplicity in design they are also suitable for manufacture with a printing process for the antennae. A development target is polycarbon semiconductor tags to become entirely printed. Passive RFID tags do not require batteries, and can be much smaller and have an unlimited life span.
Semi-passive RFID tags are very similar to passive tags except for the addition of a small battery. This battery allows the tag IC to be constantly powered. This removes the need for the aerial to be designed to collect power from the incoming signal. Aerials can therefore be optimised for the backscattering signal. Semi-passive RFID tags are faster in response and therefore stronger in reading ratio compared to passive tags.
Active RFID tags or beacons, on the other hand, have their own internal power source that is used to power any ICs and generate the outgoing signal. They may have longer range and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. To economize power consumption, many beacon concepts operate at fixed intervals. At present, the smallest active tags are about the size of a coin. Many active tags have practical ranges of tens of metres, and a battery life of up to 10 years.
Because passive tags are cheaper to manufacture and have no battery, the majority of RFID tags in existence are of the passive variety. As of 2006, these tags cost an average of Euro 0.20 ($0.24 USD) at high volumes. Today, as universal RFID tagging of individual products become commercially viable at very large volumes, the lowest cost tags available on the market are as low as 7.2 cents each in volumes of 10 million units or more. Current demand for RFID integrated circuit chips is expected to grow rapidly based on these prices.

The RFID system

An RFID system may consist of several components: tags, tag readers, edge servers, middleware, and application software.
The purpose of an RFID system is to enable data to be transmitted by a mobile device, called a tag, which is read by an RFID reader and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information, or specifics about the product tagged, such as price, colour, date of purchase, etc. The use of RFID in tracking and access applications first appeared during the 1980s. RFID quickly gained attention because of its ability to track moving objects. As the technology is refined, more pervasive and possibly invasive uses for RFID tags are in the works.
In a typical RFID system, individual objects are equipped with a small, inexpensive tag. The tag contains a transponder with a digital memory chip that is given a unique electronic product code. The interrogator, an antenna packaged with a transceiver and decoder, emits a signal activating the RFID tag so it can read and write data to it. When an RFID tag passes through the electromagnetic zone, it detects the reader's activation signal. The reader decodes the data encoded in the tag's integrated circuit (silicon chip) and the data is passed to the host computer. The application software on the host processes the data, often employing Physical Markup Language (PML).
Take the example of books in a library. Security gates can detect whether or not a book has been properly checked out of the library. When users return items, the security bit is re-set and the item record in the integrated library system is automatically updated. In some RFID solutions a return receipt can be generated. At this point, materials can be roughly sorted into bins by the return equipment. Inventory wands provide a finer detail of sorting. This tool can be used to put books into shelf-ready order.

Regulation and standardization

There is no global public body that governs the frequencies used for RFID. In principle, every country can set its own rules for this. The main bodies governing frequency allocation for RFID are:

  • USA: FCC (Federal Communications Commission)
  • Canada: DOC (Department of Communication)
  • Europe: ERO, CEPT, ETSI, and national administrations (note that the national administrations must ratify the usage of a specific frequency before it can be used in that country)
  • Japan: MPHPT (Ministry of Public Management, Home Affairs, Post and Telecommunication)
  • China: Ministry of Information Industry
  • Australia: Australian Communication Authority.
  • New Zealand: Ministry of Economic Development

Low-frequency (LF: 125 - 134.2 kHz and 140 - 148.5 kHz) and high-frequency (HF: 13.56 MHz) RFID tags can be used globally without a license. Ultra-high-frequency (UHF: 868 MHz-928 MHz) cannot be used globally as there is no single global standard. In North America, UHF can be used unlicensed for 908 - 928 MHz, but restrictions exist for transmission power. In Europe, UHF is under consideration for 865.6 - 867.6 MHz. Its usage is currently unlicensed for 869.40 - 869.65 MHz only, but restrictions exist for transmission power. The North American UHF standard is not accepted in France as it interferes with its military bands. For China and Japan, there is no regulation for the use of UHF. Each application for UHF in these countries needs a site license, which needs to be applied for at the local authorities, and can be revoked. For Australia and New Zealand, 918 - 926 MHz are unlicensed, but restrictions exist for transmission power.
These frequencies are known as the ISM bands (Industrial Medical Scientific). The return signal of the tag may still cause interference for other radio users.
Additional regulations exist regarding health and environmental issues.. For example, in Europe, the Waste Electrical and Electronic Equipment Directive does not allow for RFID tags to be thrown away. This means that RFID tags in cardboard boxes must be removed before disposing of them. This is important because RFID tags disrupt recycling. Health regulations exist as well; see EMF (Electromagnetic field).
Some standards that have been made regarding RFID technology include:

  • ISO 11784 & 11785 - These standards regulate the Radio frequency identification of animals in regards to Code Structure and Technical concept
  • ISO 14223/1 - Radio frequency identification of Animals, advanced transponders - Air interface
  • ISO 10536
  • ISO 14443
  • ISO 15693
  • ISO 18000
  • EPCglobal - this is the standardization framework that is most likely to undergo International Standardisation according to ISO rules as with all sound standards in the world, unless residing with limited scope, as customs regulations, air-traffic regulations and others. Currently the big distributors and governmental customers are pushing EPC heavily as a standard well accepted in their community, but not yet regarded as for salvation to the rest of the world.

From http://en.wikipedia.org/wiki/Rfid