When selecting an RFID Tag, there are nearly limitless antenna designs from which to choose. So how do you know which one is the right one for your application?
There is no such thing as a “one size fits all” RFID tag antenna. The tag’s antenna design will affect compatibility with reader antennas and effective frequency ranges. It will also interact with environmental factors in different ways depending on whether the tag is suspended in free space or affixed to metals or liquid-backed substrates.
If you select the wrong antenna, you can end up with a poor performing, inaccurate system or a system with strict limitations on what items can be read. But choose wisely and you can ensure a system with high accuracy and excellent performance across a wide range of tagged items. In pharmaceutical applications, this can mean the difference between failure during inventory tracking (or limitations to which medications can be tagged) and high accuracy and performance with a wide range of medications and form factors.
Antenna Shapes
Most RFID tag antenna designs fall into two general shape categories: The Coil and The Squiggle.
The Coil
The Coil is designed for short-range RFID applications. This type of tag is often seen in library books or identification card applications where one (or very few) item(s) are scanned at a time.
Coil designs harvest energy from the induced magnetic field from the RFID reader antenna. The range of these tags is very limited and is used in what is referred to as the antenna’s “near field.” This design is typically used in low frequency (LF) or high frequency (HF) applications.
Generally, these are not the best choice for pharmaceutical inventory tracking because of their short range. Designing tag and reader antennas that can read these tags at distances greater than a few centimeters is very expensive.
The Squiggle
The Squiggle, on the other hand, is designed for long-range RFID and is typically used in ultra-high frequency (UHF) applications. These tags are generally low cost and high performing and have become the standard for inventory tracking.
Squiggle designs harvest energy from the radiated electric and magnetic field (via electromagnetic waves) from the RFID reader antenna. This kind of communication occurs in what is known as the reader antenna’s “far-field”. The boundary between the near field and the far-field of the reader is typically around 30 centimeters. An additional benefit of the Squiggle is that it is often designed to work in both the near field and far-field of the RFID reader’s antenna.
Specialty Tags
There are also specialty antennas with application-specific designs for supporting specific form factors or host materials. The antenna’s size, shape, trace thickness, and added materials will affect the antenna’s performance in different applications/conditions. Certain antenna designs may perform better in free space whereas others may perform better when affixed to a metallic host. Form factor of the tag is also a factor; For example, a large tag may be significantly physically deformed when wrapped around a small object which would negatively affect performance.
Every host/tag/environment combination is unique so it is important that the right combination is selected for a given environment/application.
Manufacturing Challenges
Complex antenna designs make the manufacturing process more challenging. And poor manufacturing processes can lead to symptoms that are hard to distinguish from those of poor antenna design. So, when issues occur, it can be difficult to diagnose the root cause — a problem with the manufacturing process or the tag design itself. This inevitably leads to poor performing systems with ambiguous technical issues that can be impossible to solve after deployment.
DoseID Can Help
DoseID certification includes quality audits which ensure that inlay manufacturers and label converters have proper quality management systems (QMS) in place. Performance tests are also done to ensure that the tags scan well in the often-harsh healthcare environment composed of liquids, metals, and high tag density payloads.
The DoseID quality and performance certifications are performed by an independent 3rd party, The ARC Program (part of the RFID Lab at Auburn University). ARC audits a manufacturer’s QMS, conducts site inspection and interviews, tests each new inlay model. ARC’s inlay testing procedures are rigorous and are designed to change and grow as DoseID applications emerge and evolve.
Due to the importance of inlay selection, we take an active role in helping pharmaceutical partners select the right inlay for their products. We have a number of recommended inlays for various use cases. If the right inlay doesn’t exist yet, we can also work with inlay manufacturers on custom designs to suit new applications which solve for both the technical and business requirements of the application.
More information on DoseID’s quality and performance standards, can be found on our website.
For help choosing the right inlay, contact DoseID and we can begin the conversation.