RFID TAGS, CLASSIFICATION ON FREQUENCY OF USE

RFID tags are classified according to well-defined operating frequency bands:

• 125/134 kHz (LF Low Frequencies, for passive tags only, valid worldwide)
• 13.56 MHz (HF High Frequencies, for passive tags only, valid worldwide)
• 433 MHz (UHF Ultra High Frequencies low, for active tags only, in Europe only)
• 860-960 MHz (UHF Ultra High Frequencies medium, depending on the continents which have different maximum powers and frequency bands)
• 2.4 GHz (UHF Ultra High Frequencies High, mainly for active tags, although passive tags also exist, worldwide)
• 5.8 GHz (SHF Super High Frequencies, active tags only, used for automatic access to toll highways via Telepass)
• 5.8 GHz (UWB Ultra Wide Band – 3.1 GHz-10.6 GHz -, active tags only).

LF and HF tags are foreseen by ISO standards as passive (without batteries) while UHF and UWB tags can be active, semi-active and passive.

VM Vision distributes UHF tags, ideal for applications where high reading distances, even of a few meters, are required. UHF tags are mainly used for the identification of pallets and packages, in the automotive sector for the traceability of vehicles along assembly lines for production control, for the labeling of products within the logistics chain, for the control of highway tolls.

UHF technology is used to implement the GS1 EPCGlobal (Electronic Product Code) standard which allows the sharing of logistical information between manufacturers, distributors and retailers, similarly to what happens with barcodes or 2D Datamatrix codes.

EPC is the GS1 standard that uniquely and unequivocally identifies individual products, records important information for the movement of goods along the supply chain and makes it available thanks to radio frequency. EPC is a unique code that also contains a serial number. Number that identifies the single piece unequivocally, not just the type of reference, as the EAN code does.

EPCglobal is a joint venture between GS1 and GS1 US. It is an organization established to achieve worldwide adoption and standardization of Electronic Product Code (EPC) technology. Currently the group’s main goal is to create both a global standard for RFID and to use the Internet to share data via the EPCglobal Network.

RFID TAGS. TRANSPORT CAPACITY AND DATA TRANSFER SPEED

Considering the data transport capacity, tags range from 64 bits to a few dozen kbytes and transfer speeds start from a few hundred bits per second up to a maximum of 1 Mbit/s.

RFID TAGS. CONNECTION TYPES

There are two types of RFID Tag connection:

• Inductive or magnetic
• Electromagnetic

Inductive, or magnetic, coupling is typically used for systems with frequencies up to 27 MHz and operating distances of no more than 1.5 meters. Magnetic transponders use the propagation of magnetic fields to transmit energy and data from the reader to the transponder and data from the transponder to the reader. Their advantage is that they can be inserted into almost all objects since the magnetic field is difficult to shield and permeates almost all materials, excluding magnetic and highly conductive metals. One of the limitations is that, in order to be read correctly, the tags must be facing the reader in a specific direction. Other causes of disturbance for magnetic transponders can be the presence of powered electrical wires that create other magnetic fields or polar liquids (such as distilled water) that absorb the magnetic field. VM Vision distributes transponders with magnetic connection. Electromagnetic coupling is used when the signal frequency exceeds 27 MHz. Electric transponders exploit the propagation of electric fields and are able to communicate with the reader regardless of its orientation. Their operation may not be correct in the presence of materials impenetrable to radio waves or in the presence of other radio sources having the same frequency or a multiple of the frequency used. Electric transponders are ineffective at very short and very long distances. They typically have an operating range of 1 to 10 meters.
In order to reach greater distances, active transponders must be used which, thanks to the built-in battery, are able to communicate even at distances of the order of kilometers. Of course, the greater the distances, the larger the antennas and batteries will be.