HF RFID Tag
HF RFID tags use near-field inductive coupling to power and communicate with the reader. They have a higher memory capacity and are less sensitive to metals or liquids than UHF tags.
This makes them well-suited to applications like inventorying kegs in a beer store or tracking construction equipment in a laydown yard.
Read Range
The read range of an RFID system depends on many factors such as RF transmit power, sensitivity, surroundings (like how much water is present), orientation, frequency of operation and the care that’s gone into designing, planning and installing your RFID system. In general, the higher the operating frequency, the greater the read range.
High frequency (HF) RFID operates at frequencies ranging from 300 MHz to 1000 MHz. The HF spectrum is used by passive tags and interrogators that use far-field radiative coupling to communicate with each other using backscatter signals. These signals HF RFID Tag are the result of reflected RF waves that are picked up by the reader antenna after they are absorbed into the tag’s integrated circuit.
HF RFID waves can pass through most materials except water and dense metals. This makes HF RFID suitable for many item-level applications like document tracking, casino chips and playing cards, and laundry.
The orientation of the tagged items and the reader antenna also affects read range. Circular antennas work well in situations where the orientation of the tags or readers varies, but linear antennas are better when the tagged items and readers all need to be in the same exact orientation to achieve maximum read range. Some readers have special directional antennas that help focus the energy into a beam. This can improve the performance of your system, especially in environments with a lot of background electrical noise or moisture.
Power
HF RFID technology is more advanced than LF, works well tracking metal objects and has the ability to read multiple tags at once. It also has a lower cost per tag and is widely used for inventory tracking, asset management and in retail item-level applications. HF RFID tags can be embedded in various materials to allow for flexible placement. For example, a tag can be embedded in a plastic or laminated to make it resistant to harsh environments. HF RFID reader hardware is compact enough to be integrated into handheld devices like smartphones used in inventory and picking operations. The RFID data captured is then processed by a connected computer to automate business functions.
Passive HF RFID tags use the energy from an RFID interrogator’s signal to power their microchip and return a backscatter signal. The signals are read through the antenna and attenuated by the environment due to the diffraction, reflection and refraction of radio waves. The result is a zone called the interrogator field, or IZ, that is read at different strength levels by the RFID tag.
HF ISO 18000-3 Mode 2 tags have fast data transfer, limited issues with liquids and metals and are popular for documents, casino chips and playing cards. They are not as durable as passive LF tags and have a shorter operating frequency, making them more susceptible to interference.
Coupling
A HF RFID tag antenna can employ either electric or magnetic coupling. Inductive coupling is used for proximity-coupled HF tags, and this uses the reader and tag’s shared magnetic field to transfer electricity between the two. Closed-loop systems rely on electric field coupling, where the tag’s secondary winding coil is connected to a primary reader coil and when they are within close proximity their fields combine to transmit data to each other. This type of communication is less prone to interference from metal and liquids, and the reading range is based more on transmission power than on tag size and antenna design.
Electromagnetic waves are transmitted from the interrogator to the tag antenna via far-field coupling, and a small amount of energy is reflected back to the interrogator by the tag. The energy reflected back to the interrogator is modulated by changing the resonant properties of the tag’s antenna. The resulting signal is interpreted by the interrogator as data.
Some UHF readers use backscatter to communicate with a passive tag, and this is most common in applications that require close contact such as race timing, file tracking and inventory control. However, many UHF readers will switch to magnetic/inductive coupling when the tag is farther away from the interrogator, and this is the preferred method in logistics and supply chain applications.
Security
There are a few security measures that can be taken to prevent hacking and other malicious activities. Most of these involve some form of encryption that encrypts the communication between tag and reader, making it difficult for outsiders to read the information. This does require more computational power on the tags, which can impact their cost and read ranges.
HF RFID tags are popular for item-level tracking, supply chain management and customer experience applications like ticketing payments or brand/item interactive experiences. They are also commonly used in items that are sensitive to liquids and metals, such as pharmaceuticals, medical devices and laundry. They are less expensive than UHF tags and are typically able to read multiple tags at once due to their smaller size and more advanced technology.
In addition to anti-collision, HF RFID tags are designed with serialized Transponder ID (TID) numbers and passwords that must be programmed into them at the factory to prevent cloning. This combination of password and TID allows the HF RFID Tag tag to be authenticated if tampered with and will stop any unauthorized reading or data transfer.
Pepperl+Fuchs HF systems and tags support ISO/IEC 15693, allowing you to reliably track and trace vaccines in the supply chain at box and item-level. The technology also helps to prevent grey-market diversion by identifying where the product was shipped from and its intended destination in the supply channel. Electronically tamper-evident seals and labels can be attached to vaccine packaging to ensure it is not opened illegally or diverted into unauthorized channels.
