LF RFID Tag
LF RFID tags are passive and require no battery to operate. These tags have low read ranges and are often used for item identification.
LF tags have the benefit of working well in metals and liquids, which can interfere with higher frequency RFID frequencies. Understanding the advantages and limitations of each frequency can help businesses choose the right tag for their application.
LF RFID Tag Applications
The low frequency range (LF) has been around since 1979 for RFID applications. This technology is used for things like animal tracking and point of sale/retail identification. It has a limited read range and is not well suited for metal or liquids. It works on inductive coupling where a magnetic field generated by the reader’s coil induces electricity in the tag’s coil and communicates with the microchip.
LF tags have the lowest cost but can be difficult to work with in environments where they must be read over long distances or through thick materials such as RFID Keyfob plastic or wood. They are better suited to a more centralized tag reading system such as a store’s inventory.
High frequency (HF) is more advanced than LF and offers higher memory capacities but also has lower read ranges. HF is very sensitive to metals and liquids and can be affected by other radio waves. This technology is commonly found in things like library books and ticketing payments.
Ultra high-frequency (UHF) offers the highest read ranges and fastest data transfer rates but requires more expensive tags and readers. UHF is often used in warehouses and manufacturing facilities. It can be used for a variety of applications including asset tracking, laundry, automotive control as vehicle immobilizers and various point-of-sale applications (like Mobil/Exxon SpeedPass). It is also often used in contactless payment systems such as credit cards and NFC technology.
LF RFID Tag Technology
LF RFID tags use radio frequency transmission that uses electromagnetic induction to communicate with a reader. When the RFID tag antenna comes within range of the RFID reader, it receives energy from electromagnetic waves sent from the reader’s antenna, allowing the IC on the tag to transmit data to the reader. When the tag signals its data to the reader, the RFID reader interprets those signals and turns them into useful information for the business.
Compared to higher-frequency technologies, LF RFID systems have a shorter read range and slower data transmission speed. However, LF technology is less sensitive to interference and works well in moist environments, as well as with metals and liquids (which can interfere with other types of radio wave transmissions).
The most popular application for LF tags is animal tracking. They’re also used for access control, LF RFID Tag asset tracking and vehicle immobilizers.
LF RFID systems are more affordable than other technologies, but they do have some limitations. Their read ranges aren’t as long, and they may not be able to access a tag behind certain materials. For example, a grocer’s meat case might be filled with aluminum foil. HF or UHF tags might be needed in those conditions to get a complete reading. In addition, LF tags don’t provide anti-collision capabilities, meaning that multiple tags might transmit at the same time.
LF RFID Tag Cost
The LF RFID tag has lower cost than many of the other RFID tags. The LF RFID antenna and reader combination costs a few hundred dollars or less to get started. However, the more sophisticated active RFID tags cost significantly more than LF passive tags. These are the ones that emit a continuous radio “beacon” to identify assets, and they communicate with a database to update information as needed. Active RFID is typically used in more expensive inventory management systems that need to track and update high-value or highly variable assets.
A key consideration in the cost of any RFID system is the read range required. LF RFID tags can be read up to 1 foot away from the reader, but the HF and UHF RFID tags offer much greater reading ranges, allowing them to track or locate items over a longer distance.
As with all RF technology, environmental influences can have an impact on LF RFID tag and reader performance. For example, metal objects can interfere with LF signals, and objects made from reflective (e.g. metal) or absorbing materials (e.g. water) can block the signal or decrease the read range (Segura-Velandia et al. 2016; Verein Deutscher Ingenieure 2008).
Other environmental factors that can influence read range include the temperature of the tag and the reader, as well as moisture and other weather conditions. For example, a hyrophobic radome can be used to protect an RFID tag from water and prevent it from becoming wet or damp and thereby reducing its read range (Le Breton et al. 2017).
LF RFID Tag Features
LF tags operate at a lower frequency, requiring the tag and reader to be very close together (centimeters or inches). They have a long wavelength that easily penetrates metal surfaces such as those found on containers of milk and produce. They also work well in liquids and aqueous environments. This makes LF tags ideal for animal tracking and pet ID, or for items such as towels and books that might be damp.
As the technology continues to develop, LF tags are now available with more memory, longer read ranges and faster data transfer. LF RFID readers can typically provide a Software Development Kit (SDK) with samples of API code, documentation about the reader and its capabilities as well as test software to help a developer integrate RFID tags and systems into their own applications.
The most significant downside to LF tags is their limited lifetime, which is based on the type of battery used. The presence of a battery necessitates more complex circuitry that requires more power, which in turn decreases the lifespan of the tags. This is not a deal breaker, as the cost of the tag is still less than that of a barcode, making RFID systems more economically viable. As a result, companies are rapidly adopting the use of LF tags for their inventory and tracking needs.
