Technical – RFID

What is RFID


Radio Frequency Identification (RFID) is the generic name for a type of auto-identification technology that uses radio waves to identify unique items. Typical RFID systems are made up of two major components: the reader and the tag.
The reader, which is also known as the interrogator, may be either a fixed or mobile reader or indeed, in many applications, can be a combination of both. Its role is to read and write information from/to the tag through radio waves via the reader’s antennas.
The tag, or transponder, is made up of a microchip that stores the information, an antenna and a carrier to which the chip and antenna are mounted. RFID tags come in many different forms and sizes and can be either Active or Passive.
System Label’s RFID technology is used in many applications from security and access control through to transportation and logistics. Essentially, RFID can be used in any application where there is a need to collect multiple pieces of data on items for tracking and counting purposes and where other auto-ID technologies such as barcodes, etc. are not suitable.


In any RFID application one of the most important considerations will be what data is stored and retrieved, as well as how this data will then be used by your organisation in order to gain competitive advantage. To a large extent this will be determined by whether your application is a closed loop system, in which the RFID readers and tags are all part of a single RFID system, or whether it is part of an open-loop system, which requires it to share information with other applications. The use of various data collection software applications and middleware applications will be key here.




System Label’s RFID labels contain a small microchip that is attached to an antenna. The microchip is capable of storing encoded information such as a unique ID number which can be retrieved when activated by a suitable RFID reader. The main advantage of RFID is that it does not require a line of sight unlike competing solutions such as barcodes. A number of frequency bands exist for RFID making RFID suitable for a wide range of applications. For more information on RFID or to discuss your specific RFID application in more detail, please contact us.


Active Tags


Active RFID tags have their own internal power source and continually transmit a signal, or beacon, usually at a set time interval so as to optimise power. They generally have bigger memories than both passive and semi-active tags and the read ranges achievable are typically much larger also, with up to 100m ranges possible in many cases. Active tags are typically found in enclosed housings and come in a range of different sizes and designs to suit many different applications. While the lifetime of each tag is dependent on the time interval of the signal, it is possible to achieve a battery life of between 5 and 10 years.


Passive Tags


Passive tags, as their name implies, have no internal power, or if they do they do not use it in the transmitting of the signal. Passive tags are energised via the incoming Radio Frequency (RF) signal from the reader, which generates a small current in the antenna. This current activates the silicon chip in the circuit, effectively waking it up and thus enabling the RFID tag to send out a response to the reader. The aerial or antenna of passive tags is designed to both pick up and transmit an RF signal.
Since they do not require their own power source, passive tags are typically smaller than active tags and can come in a variety of different forms, such as self-adhesive labels, laminated paper tickets, laminated plastic cards or enclosed in specialist housing for application on difficult surfaces such as metal. Passive tags can have read distances from 2mm (ISO 14443) to a few meters (ISO 18000-6) depending on the particular Radio Frequency used and the design of the antenna. Passive tags may also contain batteries, but these batteries are not for transmitting data but for retaining the memory of the tag. As passive tags do not generally have an internal source of power they are cheaper than Active tags.




RFID readers, which are often called Interrogator or scanners, send and receive RF signals that transmit data to and from the tag via antennas. A reader may have multiple antennas for the transferring and receiving of data. RFID readers are usually in the on state waiting for a response from any tag that comes within the vicinity of the read zone. However, there are situations (for example with hand held readers) where they are activated via a trigger so as to conserve power. Tag readers can come in many shapes and sizes from small hand held PDA type readers to more industrial fixed readers such as those typically found in warehousing loading bays.