LF RFID Tag
LF RFID Tag are used in applications that require a small footprint. They can be made into different form factors such as card, glass tube, coil and plastic brick tag.
These tags work by inductively coupling with the reader antenna using magnetic fields. Unlike HF and UHF, LF technology is suitable for tracking metal objects and water-containing substances (like fruit and beverages). They also offer more data capacity than HF and UHF tags.
Low Power Consumption
The LF RFID tags do not emit any radio waves until they receive a signal from the interrogator, thus conserving power. LF tag antennas are very short, about half of the wavelength at 900 MHz (about 16 cm at 2.4 GHz). The reader antenna also has a much shorter length, and the whole system consumes significantly less power.
LF tags use near-field inductive coupling to obtain power and communicate with the interrogator. When the tag is within a few inches of the reader, the magnetic fields from the reader’s antenna induce voltage in the LF tag’s coil windings, just like primary and secondary windings of a transformer. This power is enough to activate the LF chip and transmit data, but not so strong that the tag radiates energy into the environment.
The LF tag’s read range is limited to a few centimeters or inches, but it is more than enough for most applications, including access control. It is also used in animal identification and in automobile control as a vehicle immobilizer tag. LF tags are available in different form factors, LF RFID Tag such as LF card tag, LF glass tube, LF coil, LF plastic brick and LF disc.
Short Range
Low Frequency tags operate in the frequency range 125 kHz134.2 kHz and are passive tags that use inductive coupling to receive power and transmit data to the interrogator. They have a very short read range and a relatively slow transmission rate, but they are less susceptible to interference from liquids and metals, which makes them well-suited for applications like inventorying beer kegs and automobiles.
The reading distance for LF RFID Tags falls off rapidly as the tag moves away from the reader, even if the two are at the same physical contact point (this is referred to as the induced field). This short read range can make the technology difficult to use in some situations.
To overcome this limitation, LF RFID Tags have multiple antenna turns to increase the range. For example, the tag pictured here, a glass encapsulated RFID tag that can be implanted into animals, has several hundred turn coils. Other types of LF tags are available that have planar, single-turn coils or even whip antennas — a design that works best when mounted on or in metal.
LF tags can be manufactured in many form factors, including a plastic brick, a glass ampoule and a disc tag. The LF card tag is often used for access control, the LF glass tube tag is widely used in animal tracking and livestock management and the LF brick tag excels at applications requiring a small footprint that can fit into tight spaces or be embedded in metal.
No Hazardous Environment
As with UHF tags, LF tags do not require the same precautions around metals and liquids to prevent complications such as de-tuning or multipath. This makes them a more versatile solution for industrial identification in environments like harsh warehouses or outdoors, where conditions can be unpredictable. For example, healthcare industries use RFID to track instruments that are sterilized in punishing autoclaves, but these tags must be completely encased in plastic and withstand high temperatures to work properly.
LF transmission is also able to read tags behind thin-metal substances, such as aluminum foil. It can even work in moist conditions where higher frequencies such as HF struggle for reads. This feature is particularly useful in food manufacturing applications where LF tags can be used to track items in moist situations, such as in a meat case or on a ham wrapped in aluminum foil.
LF RFID tags can be found in a variety of form factors, including cards, glass tubes, coils and plastic bricks. They can also be embedded in assets for a range of uses, from immobilize management to inspection and work-in-process management. Additionally, LF 125KHz RFID disc tags can be applied to a variety of containers and are popular for tote or pallet identification. These tags are also available in a pot core version, which allows them to be mounted flush into metal without degradation of performance.
Cost-Effective
Unlike UHF tags that require an active power source to transmit a signal, LF RFID tags are passive. They get their power from the magnetic flux of a reader, and are able to transmit data in all directions. The technology is also much less expensive than high-frequency RFID.
As an added bonus, LF RFID systems work well in moist conditions where other frequencies like UHF struggle for reads. LF tags are commonly used for access control, laundry, animal identification, automotive control (such as vehicle immobilizers), and various point-of-sale applications (such as Mobil/Exxon SpeedPass).
While some staff may be concerned about the additional workload that RFID requires, they should realize the value of this system in terms of cost-efficiency. In healthcare environments, for example, the system can help limit waste by limiting the amount of time equipment is left out of service due to misplacement. Additionally, the system can reduce manual tracking and inventory costs by allowing for a more efficient supply chain management process.
The cost-efficiency of RFID is even more apparent for businesses that frequently move costly equipment between locations. Whether it is test equipment, computer tech, or LF RFID Tag field vehicles, keeping track of these assets can be extremely expensive. With RFID, this cost can be dramatically reduced by enabling the tracking of equipment from warehouse to retail floor with no need for manual labor.
