How RFID technology works?

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Published: 31st October 2012
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Writer: Tzachi B

RFID technology uses radio waves to send information between a reader and an electronic tag attached to an object for identification and tracking purposes.

Tags (or inlays) contain a memory chip and an antenna. Information contained in the memory chip can write, read and update many times during the life of the product. Users can also perform a variety of actions with special RFID readers, including locking the data inside the chip, writing new data to the chip, creating private areas, and even "killing" the tag electronically after its final use.

Radio signals from the reader stimulate the tag. In response, the tag transmits the unique identification number of the tagged object back to the reader, as well as other data stored on the chip. The writing process, or the update of the tag data, is accomplished in a similar manner, by sending a suitable command from the reader.

In general, the RFID tags can be classified into three main categories:

Passive tags contain no internal energy source, and normally do not transmit at all. When there is a query from the reader an electromagnetic field transmitted from the reader and absorbed by the antenna of the tag the tag utilizes the absorbed energy to activate the chip and transmit the requested information back to the reader for decoding and processing data. Passive tags have a reading range of up to 8 meters.

Active tags have an internal energy source. A battery integrated into the tag enables the chip to transmit a signal back to the reader even without a reader query. These tags can reach a reading range of over a hundred meters.

Semi-active tags are sometimes called semi-passive tags or Battery Assisted Passive (BAP). Similar to active tags, they contain an internal energy source, but it is relatively small only large enough to provide energy to run the chip alone. Like passive tags, broadcasting information back to the reader requires energy absorbed from the reader's query but because the chip has its own internal source of power, semi-active tags can reach a range of tens of meters.

The communication process between the reader and the tag is well-defined by a number of international protocols and standards which are applied by both the tag and the reader. Protocols define the details and exact order of steps that are required for communication between the tag and reader, including the definition of radio wave frequency, transmission power, transmission time, process ID of the tag, decoding process of the transmitted information and more.

Frequency ranges commonly used for RFID systems are:

LF-Low Frequency range: 125-134KHz, reading distance up to 30 cm.

HF - High Frequency range: 13.56MHz, reading distance up to 1 meter.

UHF - Ultra High Frequency band: 868-928MHz range, reading distance of several meters.

RFID technology has many advantages over uni-dimensional and bi-dimensional barcode technology, including:

Line of sight is not needed between the reader and tag

Tag information can be added, updated or changed countless times

Fast reading time - you can read dozens of tags simultaneously (vs. a single barcode at a time)

Durability tag can be placed inside the product or beneath a label, in contrast to a barcode label, which must be located on the outside of the product and thus exposed to dirt and damage that can disrupt the operation.

Contact Tadbik Advanced Technologies for help in selecting the most appropriate tag to use for your needs. We'll help you find the ideal T-RFID product based on the physical dimensions of the tag, required memory size, read range, speed reading, final position of the tag, environmental conditions...and, of course, the system costs.

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