RFID (radio frequency identification)

RFID. They are the initials of Radio Frequency IDentification , in Spanish Radio Frequency Identification . It is a remote data storage and retrieval system that uses devices called RFID tags, cards, transponders, or tags. The fundamental purpose of RFID technology is to transmit the identity of an object (similar to a unique serial number) using radio waves. RFID technologies are grouped into so-called Auto ID (automatic identification).

RFID tags are small, sticker-like devices that can be attached to or incorporated into a product, animal, or person. They contain antennas to allow them to receive and respond to radio frequency requests from an RFID emitter-receiver. Passive labels do not require internal power, while active labels do. One of the advantages of using radio frequency (instead of, for example, infrared) is that no direct vision is required between emitter and receiver.


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  • 1 Architecture
  • 2 Types of antenna
  • 3 Standardization
  • 4 Benefits and advantages
  • 5 Current use
    • 1 Textile-health sector
    • 2 Human implants
  • 6 Sources


The mode of operation of RFID systems is simple. The RFID tag, which contains the identification data of the object to which it is attached, generates a radio frequency signal with said data. This signal can be captured by an RFID reader, which is responsible for reading the information and passing it in digital format to the specific application that uses RFID. An RFID system consists of the following three components:

  • RFID tag or transponder: composed of an antenna, a radio transducer and an encapsulated material or chip. The purpose of the antenna is to allow the chip, which contains the information, to transmit the tag’s identifying information. There are several types of labels. The chiphas an internal memory with a capacity that depends on the model and varies from ten to thousands of bytes .

There are several types of memory:

  • Read only: the identification code it contains is unique and personalized during the manufacture of the label.
  • Reading and writing: the identification information can be modified by the reader.
  • Anti-collision. These are special labels that allow a reader to identify several at the same time (usually the labels must enter one by one in the reader’s coverage area).
  • RFID reader or transceiver: consisting of an antenna, a transceiver and a decoder. The reader periodically sends signals to see if there is any tag in its vicinity. When it picks up a signal from a tag (which contains the tag’s identifying information), it extracts the information and passes it to the data processing subsystem.
  • Data Processing Subsystem or RFID Middleware: provides the means of data processing and storage.


  • Own power supply by long-lasting battery (generally lithiummanganese dioxide batteries )
  • Writing reading distances greater than 10m to 100m generally.
  • Various technologies and frequencies.

Up to 868 MHz ( UHF ) or according to applied standards. Widely used 2.4 GHz ( ISM , Industrial Scientific and Medical band), the same as for 802.11b wireless LAN devices .

  • Memory generally between 4 and 32 kB
  • Manufacturers: TagMasterIdentec Solutions , Siemens , Nedap , WhereNet , Bluesoft , Syris RFID .

The main advantage of active RFID tags over passive ones is the high reading range, in the order of tens of meters. As disadvantages, it is worth noting the price, which is much higher than passive tags and dependence on battery power. The life time of batteries depends on each tag model and also on its activity, it is normally in the order of years. To facilitate battery management, it is common for active RFID tags to send battery level information to the reader, allowing them to replace in advance those that are about to run out. In the market there is a varied range such as the TagActive RFID SYTAG245-2C that has the aforementioned characteristics: Communication frequency: 2.45 GHz Frequency range: between 2.40 and 2.48 GHz (125 kHz or 13.56 MHz option ) Channel: 255 Address: 65536 Wake on radio addresses: ON / OFF RSSI: 0-255 ID: 64 bits. Programming: configurable from commands. Led: action or status. Switching: configured as active tag or ON / OFF tag. Memory: 4 to 32 kbytes (optional). Battery: 3 VDC CR2032 × 1 or × 2 Battery life: 1 to 10 years Consumption at rest: 3 uA @ 3 VDC. Operating consumption: 24 mA @ 3 VDC Operating temperature: between -10 and 55 o C Storage temperature: between -20 and 65 oC Relative humidity for storage and operation: 5% to 95% Active RFID tags SYTAG245-2K, SYTAG245-2S, SYTAG245-TM can also be found.

Types of antenna

The type of antenna used in a tag depends on the application for which it is designed and the frequency of operation. Low frequency (LF) tags typically use electromagnetic induction. Since the induced voltage is proportional to the frequency, the necessary voltage can be produced to feed an integrated circuit using a sufficient number of turns. There are compact LF tags (such as glass encapsulations used for human and animal identification) that use a multi-level antenna (three 100-150 turns each) around a ferrite core. In high frequency (HF, 13.56 MHz) a flat spiral with 5-7 turns and a form factor similar to that of a credit card is used to achieve distances of tens of centimeters. These antennas are cheaper than the LF since they can be produced by means of lithography instead of expiration, although two metal surfaces and an insulator are necessary to cross connect the outer level to the inside of the spiral, where the condenser is located. resonance and integrated circuit. Passive ultra high frequency (UHF) and microwave tags are often radio coupled to the reader antenna and use classic dipole antennas. Only one layer of metal is required, reducing cost. Dipole antennas, however, do not conform very well to the characteristics of typical integrated circuits (with high input impedance, slightly capacitive). Folded dipoles or short loops can be used as complementary inductive structures to improve feeding. Half-wave dipoles (16 cm at 900 MHz) are too large for most applications (for example, tags for use on labels cannot measure more than 10 cm), so antennas must be bent to meet needs of size. Broadband structures can also be used. The gain of compact antennas is usually less than that of a dipole (less than 2 dB) and can be considered isotropic in the plane perpendicular to its axis. Dipoles experience coupling with radiation that is polarized on their axes, so the visibility of a tag with a simple dipole antenna depends on its orientation. Tags with two orthogonal antennas (double dipole tags) depend much less on it and on the polarization of the reader’s antenna, but are usually larger and more expensive than their simple counterparts.mm to achieve good bandwidth, plus a ground connection is required which increases cost compared to simpler single layer structures. HF and UHF antennas are usually copper or aluminum. Conductive inks have been tested on some antennas finding problems with adhesion to the IC and stability of the environment.


RFID standards address four fundamental areas:

  • Air Interface Protocol – Specifies how RFID tags and readers communicate via radio frequency.
  • Data content: Specifies the format and semantics of the data that is communicated between labels and readers.
  • Certification – Tests that products must meet to ensure they meet standards and can interoperate with other devices from different manufacturers.
  • Applications: uses of RFID systems.

As in other technological areas, standardization in the field of RFID is characterized by the existence of several groups of competing specifications. On the one hand is ISO, and on the other Auto-ID Center (known since October 2003 as EPCglobal, [11] from EPC, Electronic Product Code). Both share the goal of getting low-cost labels that operate in UHF. EPC standards for labels are of two kinds:

  • Class 1: simple, passive, read-only label with a once programmable non-volatile memory.
  • Class 2: read-only label that is programmed at the time of chip manufacturing (not reprogrammable later).

Classes are not interoperable and are also incompatible with ISO standards. Although EPCglobal is developing a new generation of EPC standards (called Gen2), with the aim of achieving interoperability with ISO standards, the 8-bit AFI (Application Family Identifier) ​​is still under discussion. For its part, ISO has developed RFID standards for automatic identification and management of objects. There are several related standards, such as ISO 10536, ISO 14443 and ISO 15693, but the series of standards strictly related to RFID and the frequencies used in such systems is the 18000 series.

Benefits and advantages

  • Combination of different technologies, RFID and the Internet.
  • Audio book for young people: when Nabaztag recognizes the RFID chip, it initializes the reading of the book in a live voice, and allows it to be enriched in different ways with interactive and online applications, while preserving its form on paper.
  • Supplier of identification and location of articles in the most immediate, automatic and precise supply chain of any company, in any sector and anywhere in the world.
  • Faster, more accurate readings (eliminating the need for a direct line of sight).
  • Lower levels in inventory.
  • Improves cash flow and potential reduction in overhead.
  • Reduction of stock breaks.
  • Ability to inform staff or managers when shelves need to be replaced or when an item has been placed in the wrong place.
  • Decreased unknown loss.
  • It helps to know exactly what elements have been removed and, if necessary, where to locate them.
  • Integrating it with multiple technologies – video, location systems, etc. – with RFID readers on shelves help prevent shoplifting.
  • Better use of assets.
  • Track your reusable assets (packaging, packaging, trucks) more accurately.
  • Fight counterfeiting (this is essential for the administration and the pharmaceutical industries).
  • Withdrawal from the market of specific products.
  • Reduction of costs and damage to the brand (breakdowns or loss of sales).

Current usage

Depending on the frequencies used in RFID systems, the cost, range, and applications are different. Systems that use low frequencies also have low costs, but also low usage distance. Those that use higher frequencies provide longer reading distances and faster reading speeds. Thus, low-frequency ones are commonly used for animal identification, beer keg tracking, or as a car key with an anti-theft system. Sometimes they are inserted into small chips in pets, so they can be returned to their owner in case of loss. In the united states Two frequencies are used for RFID: 125 kHz (the original standard) and 134.5 kHz (the international standard). High frequency RFID tags are used in library and book tracking, pallet tracking, building access control, airline baggage tracking, clothing item tracking and now latest in hospital center patients to track their clinic history. An extended use of high frequency labels as identification of accreditations, replacing the previous magnetic stripe cards. It is only necessary to approach these badges to a reader to authenticate the wearer. UHF RFID tags are commonly used commercially in pallet and container tracking,Asturias – Spain ) or even in flat clothing, as long as the tag is encapsulated in epoxy resin, for greater resistance to the calendering process and water extraction garment. Textile-health sector

Textile-health sector

At present the costs of textile RFID have been dramatically reduced. The most resistant are encapsulated in epoxy resin, which are also suitable for automatic garment distribution systems (cabinets, lockers or hanger systems). These can be inserted into the garments very discreetly, inside the hems, heat-sealed or simply sewn. The ideal is the correct one inserted in the garments, because the position is very important since being located in certain areas, can give an error in the reading. The importance of reading quality is essential, having previously selected the hardware, antennas and readers, as well as being located in a non-metallic or properly isolated environment is crucial for achieving 100% of reading. Today, thanks to the anti-collision protocol, dozens of garments or objects can be read in bulk without having direct visibility or without having to remove the garments from the laundry bags, boxes or plastics in just a few seconds. Thanks to this product in the textile sector, the processes of laundry, lingerie and automatic dispensing of clothes in sectors such as healthcare or fashion, the optimization of human resources and a reduction in stockpiles are achieved, which are extremely important up to 35% in the Direct stock and a reduction of up to 50% in the loss, loss or theft of garments. Elements such as reading tunnels are devices that help the user of these systems very precisely, reaching 100% of reading. In Spain the rise of this technology, It is clearly growing, although there are very few companies that can offer guarantees of success in the implementation and advice on the devices to be used, always HF. A good technological partner in this field is important that it is able to perfectly size the system. In the case of flat clothing, its use is highly conditioned to the selected tag, being the most important part to ensure the correct operation of said clothing. The tags encapsualdos in epoxy resin, have proven to be the only ones resistant to the demanding washing processes, where garments are used to extract the excess water after the car wash and resistant to the calender, which due to the pressures exerted on the clothing, up to 9 bars, although it is recommended to reduce it to 3 bars (enough to secure the fabric),o C. If its use is required in this clothing, the epoxy encapsulated tag is the most recommended, since other flat cotton or plastic tag solutions end up breaking or melting, with the consequent damage to the project. There are several expert companies in this type of tags, although TagsysRfid is the one that can bring the most experience, due to the large number of references in the textile-health sector.

Textile chip, uniformity. Resistant to any washing process

Rfid HF chip (better than UHF in this environment, due to washing processes) “Passive” Encapsulated for use in uniform and textile sector. Special Laundries

Human implants

Implantable RFID chips, originally designed for animal tagging, are being used and are also being contemplated for humans. Applied Digital Solutions proposes its chip “unique under-the-skin format” as a solution to identity theft, secure access to a building, access to a computer, storage of medical records, initiatives anti-hijacking and a variety of applications. Combined with sensors to monitor various body functions, the Digital Angel device could provide patient monitoring. The Baja Beach Club in Barcelona (Spain) uses an implantable Verichip to identify its VIP clients, who use it to pay for drinks. The Mexico City Police Department has implanted the Verichip on some 170 of its police officers, to allow access to the police databases and to be able to follow them in case they are kidnapped. However, some studies without contrast assure that the implantation of the chips poses a high risk to health, since they are highly carcinogenic.


Amal Graafstra, a businessman from the state of Washington , in the United StatesHe had an RFID chip implanted in his left hand in early 2005. The chip was 12 mm long by 2 millimeters in diameter and had a range of reading for two inches (50 millimeters). The implantation was performed by a plastic surgeon, although the doctor’s name was not disclosed. When asked what he intended to do with the implant, Graafstra replied: “I am writing my own software and I am welding on my own material, practically this is what I want. Well, more precisely, something that I have the time and inspiration to To be able to do it. Ultimately though, I think true keyless access will require an implantable chip with a very strong encryption system – now I only see this kind of thing in a personal context. ”


by Abdullah Sam
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