The AD9361 Tested in a UHF RFID Reader
The AD9361 Tested in a UHF RFID Reader
The AD9361 is used in the RF front end of an UHF RFID reader to test system-level RF performance. An adaptive SJC algorithm and the RF envelope of an RF transmission are tested to meet China GB/T 29768-2013 and GB/T 35786-2017 standards.
The range of an UHF RFID tag depends on its chip characteristics, the operating environment and the RFID reader parameters. A pattern reconfigurable UHF RFID reader antenna increases reading range.
What is UHF RFID?
Ultra-high radiofrequency identification (UHF RFID) operates in the 840 to 960 MHz frequency range and has a longer read range than LF or UHF RFID Reader HF RFID. This makes it a popular choice for tracking assets in many different applications, such as manufacturing, retail, supply chain, and parking (vehicle) access control.
A UHF RFID tag consists of an integrated circuit (IC) and an antenna. To communicate with a reader, the tag transmits a continuous wave (CW) signal to power the transmitter and then receives backscattered signals at the same frequency from the reader. Depending on the tag, an algorithm determines the order in which the tags reply to the reader, and a memory bank contains unique data for each tag that is used to identify it.
As the popularity of RFID grows, it’s important for businesses to understand how different protocols and standards work so they can choose the right solution for their needs. Choosing the right RFID system helps companies streamline critical business processes, improve operational efficiency, and increase return on investment.
UHF RFID Tags
UHF RFID tags consist of a chip that contains all the data needed for identification and a transponder antenna that sends that information to the reader. The tag also has a user-interactive sensor that can be programmed to trigger specific actions or report conditions.
The choice of a UHF RFID tag depends on the specific business needs and physical environment. Factors include the type of surface material on which a tag will be attached, the size of the item to be tagged, and the desired read range. The tag’s surface materials can affect its performance, so it is important to test readability in a variety of locations and positions.
A tag’s design and materials can impact its ability to withstand environmental factors such as heat, cold, moisture, and chemicals. The type of RFID chip used also determines how the tag can perform and its sensitivity to electromagnetic waves.
Some UHF RFID tags are designed for use in hazardous environments, with some ATEX certified. In addition to requiring the approval of an authorized agency, these tags must pass tests to ensure they are safe to be used in hazardous settings where flammable gases or vapors may be present. These tags are usually more expensive than non-hazardous RFID tags. They can be printed with a unique identifier and have higher memory capacity, which can store more information for more advanced applications.
UHF RFID Readers
UHF RFID readers use radio-frequency waves to wirelessly transfer data between themselves and an RFID tag/label. This information is then used to identify, categorize, and track objects. The reader uses GS1’s EPC UHF Gen 2 air interface protocol to communicate with the tag/label and receive identification, read/write, and status data.
UHF readers are available in a variety of form factors, but are typically mobile and handheld. This allows them to travel between sites with ease and be operated by shift workers without removing their gloves. While fixed systems offer a more comprehensive range of coverage, they require substantial installation and equipment costs which impedes their return on investment for many applications.
Choosing an appropriate antenna, directional coupler, and receiver are critical to achieving good system performance. Often the directional coupler limits the transmitter/receiver separation, which in turn reduces the read/write performance. This can be mitigated by using a high-performance RF front end. Analog Devices has a number of RF front-end options, including the ADF9010 and AD9963, as well as the AD9361. These implementations are designed to test system-level link UHF RFID Reader budget requirements and meet the GB/T 35786-2017 sensitivity specification of -65 dBm (receiver sensitivity at BLF 640 kHz uplink signal). The ADF9010/AD9963 solution has superior performance, providing a large margin over this requirement. The AD9361 solution is also very flexible and offers a good trade-off between sensitivity and size.
UHF RFID Applications
The most common UHF RFID application involves tracking inventory within a large facility. The technology can be used to automate supply chain processes, and the real-time inventory data provides visibility into the supply chain for improved inventory management and supply chain optimization.
The long read ranges of UHF RFID make it ideal for tracking high-value items, including pharmaceuticals, medical devices, and laboratory equipment. The technology is also more advanced than HF or low-frequency RFID, and works well even through materials like metal and water that disrupt RF signals.
Passive UHF RFID tags operate by being energized by the RF waves backscattered from their antenna. However, the CW reader signal transmitted by the interrogator can leak into the receiver and interfere with the backscattered response, degrading the sensitivity of the RFID system. To mitigate this effect, a UHF RFID reader RF front end requires good transmitter-to-receiver isolation.
An active UHF RFID tag contains a chip that can store its own data, and instead of being energized by the RF waves of the interrogator it will proactively beacon at a predetermined interval using its internal battery power. This can give the tag a very long reading range, and some tags are engineered to withstand harsh environments like extreme cold and even being buried in snow or dirt.
The ADF9010 evaluation board incorporates an SJC circuit that includes a transmitter monitor gain and a receiver baseband filter and PGA. It is cascaded with the AD9361 RF front-end to test transmitter and receiver system-level RF performance.