Radio Frequency Identification. Contactless technology

Radio Frequency Identification technology (RFID - Radio Frequency Identification) is based on the exchange of information between a radio response, one way or another connected with an object, and a polling device (reader) emitting a continuous or pulsed radio signal through an antenna. When a radio responder, called a radio tag, or a tag, passes through the reader’s reading zone, it changes its signal in a certain way and returns it. Reader determines the difference between the emitted and received signals and sets the identifier of the RFID tag in this way. The radio tag consists of a charger, a transceiver with an antenna, a control unit and a power source (if the label is active). In the absence of a power source (passive label), electricity is supplied from the signal charging the capacitor built into the RFID tag. Depending on the type of memory, tags can be read only or read / write. The distance at which information is read and written varies from a few millimeters to a few meters, depending on the technology used. RFID tags themselves are also quite different - in the form of credit cards, implanted microchips in glass cases or large tags that are attached to huge containers. RFID tags use a specific set of frequencies. The most common low-frequency tags operating at frequencies from 125 to 500 kHz. Mid-frequency devices use 27 and 430-440 MHz, and high-frequency devices use 860-915 MHz, 2.45 GHz (for containers and on railways) and 5.8 GHz (for high-speed vehicles). There is a tendency of wider use of high frequencies both for the purpose of unloading the used frequency range and for increasing the transmission speed. With the appropriate housing, radio tags operate in a wide range of environments. They are sensitive to very high temperatures and thermal shocks. In the cold passive RFID tags work better. It is necessary to note the factor of metal proximity to the tag. The low frequency signal is distorted and attenuated by the presence of a metal, especially containing iron. The RFID tag should not be placed in a full metal case, unless it is part of the antenna system. Microwave labels do not get upset, but in the presence of a significant amount of metal to minimize the effect of reflection require carefully calibrated layout.


A wide variety of radio frequency identification systems are now available. Typically, short-range systems use low frequency and low cost. The cost of radio tags does not exceed a few dollars, and for some simple systems it is even less than a dollar and has a steady downward trend. But if you need to increase the amount of memory, reading radius or speed of information exchange, the cost of the radio tag increases. However, there are no technical restrictions on the amount of information placed on the radio tag. The maximum speed of a radio tag during reading can reach 400 km / h, but one should not forget that the amount of information transmitted is inversely proportional to the speed of movement. Higher frequencies allow higher transmission speeds and are used in more expensive systems. Restrictions on the use of radio frequency identification systems are mainly imposed by the rules of using the radio frequency spectrum and the permissible power of the emitted radio signals. RFID is evolving and becoming more and more economically attractive, not only for identification, but also for data transmission. Around the world, there are now several million RFID tags working in areas such as animal identification, access control, payment collection, information transfer along production lines, along the supply chain and in many other areas. Today, a number of companies produce microchips of radio tags, which successfully combine an identifier, a carrier of personal information with the possibility of updating and an element of protection against unauthorized use or theft. EM Microelectronics, a company known in this field, recently released a family of chips at a frequency of 13.56 MHz for radio frequency identification in security systems, access control, and tracking movements of people and objects. The family, including EM4035, EM4135, EM4034 and EM4094 chips, complies with ISO 15693, provides reading at a speed of 20 to 40 tags / s at a distance of 1 m, operates in a temperature range of -40–85 ° C. The EM4035 chip contains the encryption algorithm required in universal cards for multiple access. The memory stores a unique identifier and a code programmable by the customer. The price is 80 cents (at a batch of 10 thousand pieces).

Intended for logistics and tracking in a high-density environment, EM4135 and EM4034 do not contain any encryption logic, but only the memory available to the user. The devices are mounted according to the inverted crystal method and are powered by RF energy through the antenna. Their price is up to 70 cents (with a batch of 10 thousand pieces). The EM4094 universal RFID reader is compatible with most 13.56-MHz tags. The IC of the reader has an amplitude and pulse demodulator, low-pass and high-pass filters, selective receiver gain and low power mode. Multiple receiving inputs provide enhanced communication reliability. The price is $ 5 (for a batch of 1000). Radio frequency chips, with many applications in various fields, may soon “settle” in the human body. Already hundreds of thousands of different medical devices are implanted in patients annually. After implantation, these devices often require adjustment, repair, relocation, or even replacement, and all this requires large-scale information that must be stored and be accessible throughout the person’s life. To communicate with an implant, you can use Applied Digital Solutions's VeriChip passive radio frequency chip that transmits the necessary information while in the patient's body. The chip is placed directly above the implanted medical device and allows you to "contact" it to obtain fast and accurate information about the patient's name and the presence of certain implanted medical devices. In the future, it is also planned to write on the chips a complete medical history. The use of VeriChip implants is authorized by the US Drug Administration. The radio frequency chip is a capsule of 11.1x2.1 mm in size and can be implanted in any place of the human body. The scanner sends a radio signal that passes through the skin and activates an inactive chip. The identification number and all information stored on it is transmitted to the reader. Information can be displayed on the scanner itself, transmitted by phone or via the Internet to a PC, where it is processed by qualified specialists. The VeriChip RF chip has many potential applications, but this will only be possible if society accepts the use of microchips to identify a person. Chip VeriChip can be used not only for medical purposes. One of the possible areas of its application is security systems. The implantable chip is capable of replacing keys, allowing them to enter homes and cars without their help, and can also be used to ensure the security of bank accounts. Such chips have already been implanted in a million dogs and cats around the world in order to identify them in case of loss. Experts of the company Applied Digital Solutions, which has been dealing with animal chips for several years, claim that the chips for humans are mainly distinguished by a biocompatible coating that protects against the alienation of the implantable chip. Chips can be implanted in children and adults with Alzheimer's disease to help identify people who can not communicate any information about themselves. Analysts predict that the technology of human identification will become especially popular when the chips will be endowed with a large amount of memory and characteristics such as, for example, a connection to a global satellite system. The satellite system will help you find missing children and adults, and more memory will allow doctors to record vital information about the patient on chips. The European Central Bank is working on a project to equip every euro note with a radio frequency tag in order to prevent counterfeiting. This project is planned to be implemented by 2005. First, the chips will be "implanted" in the banknotes in denominations of 200 and 500 euros. Radio tags will help law enforcement agencies practically “follow the money” and track any illegal movements. In addition, tags can contain information about where and when notes were last scanned. Representatives of banks and chip suppliers agree that the radio frequency antenna and chip in banking is quite real, but no bank has yet applied this technology. On the eve of holidays and sales stores expect a large influx of buyers. And here a problem arises - you need to follow the goods with special care. According to the National Anti-Theft Service (USA), holiday sales are the most favorable place for shoplifters.

The stores accumulate a large number of people, they scurry from one department to another, and therefore it becomes almost impossible to track the movement of each product in the store. RFID compared with other controls at retailers offers the most realistic solution to the problem of theft, and also saves a significant portion of funds. Smart labels with a built-in RFID tag that transmit information to a reader allow you to track the movement of any product. In the read field, the device can automatically read information from hundreds of tags per second. Manufacturers have the opportunity to receive information about the location of each manufactured product until use. The RFID technology was applied by Marks & Spencer, replacing the existing barcode system with radio frequency smart labels that are attached to 3.5 million pallets and containers used throughout the supply chain. Radio frequency technology has allowed Marks & Spencer to reduce costs and increase the speed of tracking and managing batches of frozen products. Compared to bar-coding technology, the use of RFID tags reduces the time required to read information by about 80%. A container with 25 pallets can be scanned in 5 seconds (29 seconds when scanning barcodes), just passing by, and this will be done accurately and reliably. This innovation was implemented with the help of Intellident. The use of radio frequency identification technology leads to improved accounting, management and security of resources, lower costs, increased productivity, reduced time loss and more efficient use of equipment and personnel. Today it is a key technology in such areas as security, transportation, manufacturing, medicine, trade, etc.

Electronics. Science, technology, business, 2004, No. 6 by E. Ruvinova