When it comes to radio frequency identification (RFID) solutions, ultra-high frequency (UHF) passive RFID tags are an extremely popular option because they are very cost-effective, yet still have one of the longest read ranges. They have no power of their own — which is why they are called “passive” tags — so they are powered by the radio frequency energy transmitted from RFID readers/antennas. A UHF passive RFID tag consists of four sub-components: and RFID chip, an antenna, an inlay, and a carrier.
The RFID chip is an integrated circuit that provides several key attributes related to operating frequency, memory type and capacity, data transmission/receipt, and power. In other words, the chip is the brains of the RFID tag. The antenna, which is attached to the chip, collects radio frequency waves used to power the chip. The antenna also transmits attribute data from the chip. Together, the chip and the antenna comprise the RFID inlay.
Integrated Circuit (IC)/Chip – the integrated circuit, also called the chip, contains four memory banks, processing information, send and receive information, and anti-collision protocols. Each IC type is unique, and there are only a handful of manufacturers. The main variation between ICs is the number of bits in the respective memory banks.
The four memory banks are as follows:
EPC Memory Bank – contains the Electronic Product Code which can vary in length from 96 to 496 bits. Some manufacturers use a randomized, unique number, while others use random repeating numbers.
User Memory Bank – the User memory bank can range from 32 bits to over 64k bits and is not included on every IC. If the tag does possess a User memory bank, it can be used for user defined data about the item. This could be information like item type, last service date, or serial number.
Reserved Memory Bank – the Reserved memory bank contains the access and lock passwords which enable the tag memory to be locked by the user and require a password to view or edit.
TID Memory Bank – the TID memory bank contains the Tag Identifier which is a randomized, unique number that is set by the manufacturer and cannot be changed. In order for the reader to read this number instead of the EPC, the reader settings must be changed to accommodate.
Antenna – A tag’s antenna is unique to that specific type of tag and its job is to receive RF waves, energize the IC, and then backscatter the modulated energy to the RFID antenna. For general purposes, the size of the tag’s internal antenna will be a strong indicator of the tag’s read range. Small RFID tags contain small antennas which leads to shorter read ranges, while large RFID tags (with larger antennas) will have longer read ranges. Additionally, RF antennas can be strongly influenced by their surrounding environment. Water and metal absorb and reflect RF energy respectively and, in doing so, may decrease an RFID system’s performance (read ranges and read rates).
Inlay – An inlay is typically a plastic substrate that the chip and antenna are placed on so they can be connected. Inlays come in two types: wet and dry. A wet inlay features an adhesive so it can be applied to a surface; a dry inlay has no adhesive. The choice of inlay depends on the purpose and placement of the tag on an object. There are literally hundreds of different types of inlays, each designed with a specific application in mind. Different industries have different requirements for inlays, so there are inlays for pharmaceutical, automotive, retail, manufacturing, and healthcare applications. The inlays are designed for optimum performance when affixed to the material they are intended for. Inlay manufacturers ship their products to RFID tag producers, like Lowry Solutions, who then produce finished products that are ready to be applied.
Carrier – The carrier is the material or package that the inlay is placed in. The simplest carrier is label stock (think barcode label), where the inlay is laminated into the label stock using specialized converting equipment. Examples of other carriers include plastic capsules or ID badges. Sometimes carriers are made of specialized materials that make it easy to mount the RFID tag on liquid containers or metal, or in high-heat or hazardous environments. These types of carriers are often referred to as “hard tags.”
The Ultra High Frequency (UHF) band is the frequency range from 300 MHz to 1 GHz. RFID systems that operate in this frequency band are called Ultra High Frequency (UHF) RFID Systems. UHF RFID tags/readers usually operate at 433 MHz and from 860 to 960 MHz. UHF RFID tags operate using the far-field radiative coupling principle or backscatter coupling principle.
Ultra high frequency technology, is the fastest growing segment on the RFID market. The majority of new RFID projects are using UHF, as opposed to HF or LF systems. To date, UHF technology has over 20 billion connected items providing real-time visibility and data to a myriad of everyday items. UHF systems are known for generating long read ranges, up to 15 meters (50 feet), whereas HF systems carry a much shorter read range of approximately one meter (3 feet). UHF allows for a faster data transfer rate, up to 20 times the range and speed of HF systems. This enables quicker transaction capture times and faster data processing.
As UHF solidifies its position as the global standard and preferred RFID technology across vertical markets, tag prices continue to drop. In 2017, UHF RFID tags cost approximately $.05 to $.15 per tag, whereas HF tags range from $.50 to $2.00 per tag.
UHF RFID tags have a much higher read range when compared to LF and HF tags. The high data transfer rate makes UHF RFID tags ideal for applications that need to read multiple items at once, such as boxes of goods as they pass through a door into a warehouse or racers as they cross a finish line.
The read range of UHF RFID tags can be as high as 50 feet which is much higher than that of LF and HF tags. The longer read range opens up a set of new applications for RFID such as electronic toll collection and parking access control.
UHF tags do have some downsides, one being that they operate at a higher frequency and thus have shorter wavelengths which attenuate fairly quickly and are also very sensitive to interference. These tags cannot easily be read while attached to objects containing water and animal tissues because water absorbs UHF waves. The UHF tags also do not work well with metals, as they get detuned when they are attached to metal objects.
Using a UHF RFID system eliminates the need for manual processes, thus increasing inventory visibility and automating workflows. Such as, there are countless benefits to incorporating UHF RFID systems into healthcare and life science markets, including:
•Gain real-time visibility of inventory
•Automate inventory tracking and workflows
•Prevent use of expired or recalled products
•Meet industry regulations such as FDA, UDI, and JHACO
•Remotely monitor temperature and inventory alerts
•Reduce shrinkage and prevent inventory stock-outs
•Secure access to specified areas or products
•Improve overall business operations
|UHF RFID Tag Properties|
|Tag Type||Passive / Battery Assisted / Active|
|Frequency||433 MHz and 860 to 960 MHz|
|Read Range||Up to 50 feet|
|Read Speed||Very Fast|
|Read Multiple Tags Simultaneously||Yes|
|Works with Metal||No|
|Works with Water||No|