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 RFID tags have their own internal power source and continually transmit a signal, or beacon, usually at a set time interval so as to optimize 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, 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 energized 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 to a few meters 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 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.