An introduction to RFID labels
RFID (Radio Frequency IDentification) technology has been used in industry since the 1970s and incorporated into self adhesive labels for the past decade. As one of the 3 categories of SMART labels it offers a function that no other label type can, the ability to be programmed with different data and interact with users outside the line of sight. Long speculated to be a replacement for barcodes for use at item level, the RFID label has found markets in high volume logistics, typically at case or pallet level, in brand protection and ticketing,for libraries and document management and premium value retail applications.
RFID tags operate in three frequency bands:
- o High Frequency (HF) – 13.56 MHz
- o Low Frequency- (LF) 125 – 134 KHz
- o Ultra High Frequency (UHF) – 868 – 915 MHz
LF and HF systems use the Magnetic Field of the electromagnetic spectrum to transfer power by induction. This field has a well defined zone but the strength of this field falls off quickly.
UHF systems use the electric field of the electromagnetic spectrum to transfer power by capacitive coupling. The strength of this field doesn’t fall off as quickly, so potentially longer read range is possible. However, reflections mean that the reading zone is less well defined. UHF systems also suffer signal loss or attenuation through materials. LF and HF systems do not.
Passive LF RFID
Passive LF RFID devices are constructed using a wire wound antenna around a ferrite core. They are a mature technology that has used for 20 years, using tags of variable sizes that have the benefit that the signal penetrates most materials apart from metal with little signal loss. They are however relatively expensive and bulky compared to HF and UHF RFID label tags.These are used in many areas i.e. transportation, vehicles car keys and in animals (dogs)
Passive HF RFID labels
Passive HF RFID labels are paper thin and can be converted into Smart RFID Labels in sizes from 20 x 40 to 45 x 80mm. They are an established technology that has been around for 8 years and is a lower cost than LF tags, but again suffers from signal attenuation in proximity to metal.
HF tags capacity is high though at 2048 bits including 64 bit Unique ID. There are standards in place (ISO 15693, ISO 14443 and ISO 18000-3) to ensure conformity between hardware suppliers. Readers and antenna are widely available.
HF tags are used in short to mid range multiple read applications such as stock control, ID badges and document and media management applications.
HF RFID technology is also used in the emerging ISO14443a NFC (near field communication) standard, commonly known as “NFC stickers” or “NFC labels” that can be retrofitted to smartphones and other devices.
UHF RFID labels
UHF RFID labels are significantly different from both LF and HF tags in that UHF tags are di-pole antennas and for best performance they are long, commonly over 100mm and are limited by the fact that the signal does not pass through many materials and the tags need separation from fluids and metals. Signals are also not well ready when both the tag and reader are stationary. There are standards in place (ISO18000-6 not fully ratified) for UHF readers.
RFID labelling is still in its infancy and applications need careful specification to determine suitability. If you are interested in investing in an RFID labelling application then please contact the leader of our NPD team Dr Adrian Steele with a brief outline of your needs.