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Voyantic Webinar Recap: Choosing the Right RAIN RFID Antenna

Nov 01, 2024

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32Voyantic Marketing

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Watch the full webinar recording here!

How Does Antenna Choice Impact Your RAIN RFID System?

Selecting the right antenna can make or break the performance of a RAIN RFID system. Our recent webinar on October 10, “Choosing the Right RAIN RFID Antenna”, provided a deep dive into the critical aspects of antenna selection for RAIN RFID systems. 

We explored the fundamental principles of antenna choice, essential parameters to consider, and ways to match antenna features with specific application needs.

The webinar featured insights from industry experts including Daniel Eisen, RFID Engineer at Times-7, Jos Kunnen, CTO at Times-7, along with Sami Rautanen, Senior Hardware Designer, and Teemu Ainasoja, Sales Director, both from Voyantic. 

Together, they shared valuable insights into antenna fundamentals, best practices, and considerations for optimizing RFID system performance.

Key Highlights of the Webinar

  • Key Factors in Antenna Selection
  • RF Fundamentals in RAIN RFID Systems
  • Choosing the Best Antenna Polarization for Your Needs
  • Practical Advice for Antenna Selection
  • Questions to Ask Your Antenna Supplier

Key Factors in Antenna Selection

Every application has unique requirements, so understanding the essential factors in antenna selection is crucial. Our speakers discussed parameters like frequency, wavelength, and RF (Radio Frequency) characteristics, all of which affect how antennas interact with RFID tags in various environments.

  • Frequency and radiation pattern: Each antenna has an operating frequency. RAIN RFID operates in 860 – 960 MHz, so make sure you choose the right antenna for your reader. Understanding the radiation pattern is important in order to read the datasheet and select the best antenna for your application.
  • RF Characteristics: Factors such as RF field strength and energy distribution influence how well an RFID system reads tags, especially in environments with metal, liquids, or other RF interference sources.

RF Fundamentals in RAIN RFID Systems

RAIN RFID technology relies on RF signals in the UHF range of 860-960 MHz. Understanding the behavior of these signals is key to optimizing system performance.

  • Link Budget: Losses in the RF link may cause excessive signal loss and destroy system performance. This problem can be solved with a right reader antenna with a suitable radiation pattern and polarization.
  • Signal Polarization: The webinar explained how linear and circular polarization can impact read accuracy and range. Linear polarization works well for specific orientations, while circular polarization offers flexibility for tags at various angles.
This picture shows lind budget in RF link.

Choosing the Best Antenna Polarization for Your Needs

Polarization is central to antenna effectiveness. Our experts explained how different polarization types function and when to use each based on application requirements.

  • Linear Polarization: Suitable for applications where tags are consistently aligned with the antenna. It provides strong signals in a specific direction, ideal for scenarios with controlled orientation.
  • Circular Polarization: A versatile choice when tag orientation is unpredictable, as it allows signals to be read from various angles. This reduces errors in environments like retail, where items may shift.

Practical Advice for Antenna Selection

Our webinar offered practical tips for balancing gain, beamwidth, and radiation patterns—critical parameters that influence coverage and reliability.

  • Gain: Higher gain antennas provide a stronger, focused signal ideal for long-range reads, whereas low-gain antennas are better suited for wider coverage in close proximity setups.
  • Beamwidth and Radiation Patterns: These factors determine how broadly the antenna transmits signals. For example, narrow beamwidth is optimal for focused, direct reads, while a wider beam is suitable for scanning larger areas with multiple tags.

Questions to Ask Your Antenna Supplier

To conclude, our experts provided a checklist of questions to ask when selecting an antenna supplier. Knowing terms like dBi, EIRP, and ERP, as well as understanding compliance requirements, allows you to make informed decisions that ensure efficiency and regulatory alignment.

  • dBi (Decibel Isotropic): A measure of an antenna’s gain compared to an idealized isotropic antenna. Higher dBi indicates a more focused signal.
  • EIRP (Equivalent Isotropically Radiated Power) and ERP (Effective Radiated Power): These metrics help determine the actual power output and range capacity, both essential for meeting regulatory standards.

Watch the Webinar On-Demand

Did you miss the live session? You can still access the full recording here. 

The webinar is packed with expert insights to help you make confident, data-driven decisions for your RAIN RFID applications.

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Tracking Tools with RAIN RFID – Webinar Recap

Jun 18, 2024

About the author

32Voyantic Marketing

Content

The use of RAIN RFID is increasing across industries. One of the applications where RAIN RFID has demonstrated great value is tool management – especially with the expanding availability of specialty tags designed specifically for tool tracking from multiple vendors in the industry. 

Organizations have started using RAIN RFID for better inventory management, loss prevention, and accountability.  Also, several tool manufacturers are beginning to tag tools with RAIN RFID at the point of manufacturing before tools are delivered to customers. 

Earlier this month, we hosted a webinar to address the benefits, challenges, and use cases of tracking tools with RAIN RFID. We also covered the importance of understanding the RF performance of the tagged tools when planning the applications and how you can test the performance of the tagged tools. 

Our expert speakers at the webinar were Bhavik Ghaghada from Xerafy and Rajiv Anand from InThing. 

If you missed the webinar, you can watch the recording here ›

Or you can read on for a summary of some of the key points from the webinar. 

Different tools on a red board

Why are companies using RAIN RFID for Tool Tracking?

Tool tracking with RAIN RFID provides many of the same benefits as any other application: 

  1. Enhanced inventory management – RFID enables efficient tracking and management of tool inventory, reducing losses and misplacements
  2. Increased operational efficiency – Automated tool management reduces manual labor, leading to cost savings
  3. Real-time location intelligence – RFID tags on tools can be used for tracking the location and the movement of tools within work processes, facilitating pattern detection and preventive maintenance. 

There are also some unique benefits arising from safety, compliance, and work process considerations. 

Unique RFID Use Cases for Tool Tracking

In addition to the obvious benefits of improved inventory management and loss prevention, many industries have specific regulatory, safety, and compliance requirements that require accurate and efficient tool management solutions.  

During the webinar, Rajiv covered a few interesting industry-specific examples where accurate tool management is critical: 

  • FOD in Aviation – FOD stands for Foreign Object Debris. In aviation, it is critical to ensure that no tool is left behind, for example, in a plane’s engine when it’s being maintained. FOD can potentially have catastrophic consequences.
  • FME in Nuclear – In the nuclear industry the term used is FME – Foreign Material Exclusion. Similarly to FOD, a tool left behind in the reactor or other critical locations can lead to disastrous consequences. 
  • RSI in Healthcare – RSI stands for Retained Surgical Instruments and refers to a situation where a surgical instrument is accidentally left in the patient’s body, leading to serious consequences.
  • Calibration in Research Labs – Research labs often have thousands of tools that require regular calibration for specific research projects. Missing the calibration time can lead to inaccurate research results and delays. 
  • Equipment and tools in Manufacturing – In some manufacturing processes tools are also calibrated and designed for specific jobs. A misplaced tool on the wrong workstation can lead to serious errors in the manufacturing process and product defects.
Different industries where accurate tool management is critical: FOD in Aviation, FME in Nuclear, RSI in Healthcare, Calibration in Research Labs and Equipment and tools in Manufacturing.

Why is Tool Tracking Challenging?

Tools are versatile objects, coming in many shapes and sizes. Tools are typically made from metal, which is a challenging material from an RF perspective. RAIN RFID tags that are used on tools need to be specifically designed to be used on metal objects and specific form factors.  

Tools are also often used in challenging environments. Exposure to dirt, oil, chemicals, heat, and cold also creates unique requirements for the durability of the tags. 

Tools inventories are also typically large and often stored in bags or containers where tools can freely collide with each other and are not stored in fixed positions. This also poses challenges and requirements for the RFID system and hardware. 

All these challenges can be addressed with careful system planning, testing, and deployment.

Tool Tagging saves time used on inventory checks

Why is RFID a great technology for tool tracking?

During the webinar, three key benefits could be identified that make RFID a great technology for tool management: 

  1. Digital identity – RFID provides a unique digital identity for tools and enables an efficient way for automated inventory and batch management, for example, compared to barcode technology where each item needs to be scanned individually. 
  2. Durability – RFID tags come in various sizes and form factors, including very small sizes for smaller tools. RFID tags can be protected with hard enclosures and other protective materials to make them durable enough for tools. Barcode labels and stickers with printed information are subject to wear and tear when tools are used. 
  3. Scalability – RFID systems are scalable and can be expanded to new applications and future needs of the organization. Utilizing the existing infrastructure can potentially bring additional cost savings.

Best Practices and Considerations 

First step – Tag Selection 

A critical step in an RFID-based tracking project is to select the right tag for the application. Smaller tags are suitable for tracking hand-held tools whereas power tools and larger equipment may require more rugged case and attachment options. The tool’s material also affects the choice of the tags as tags are always designed to work optimally with specific materials.  

Step two – Tag attachment

The tag attachment phase is critical for reliable system performance and a longer tag lifespan. If the tags are not properly mounted on the tool, it can lead to tags detaching from the tool or being damaged when the tool is used. 

A typical tag attachment process includes applying a base adhesive, then placing the tag on the adhesive and letting it cure.  The next step is to apply an epoxy encapsulation over the tag to protect the tag. The last step is to add heat shrink tubing that protects the tag from external factors and keeps it tightly attached to the tool.

A tag is attached to the tool with base adhesive. After the tag is mounted an epoxy encapsulation will be made. Last heat shrink tubing will be installed.

Tag Position and Orientation 

Tool tags are typically designed to be mounted to a specific orientation in relation to the tool. One reason for this is that the metal in a typical tool, such as a wrench, also affects the tag’s performance. When the tag is aligned with the tool as designed by the tag developer, the performance of the tags will be more consistent, leading to more consistent application performance. 

You should also avoid placing the tags where they interfere with using the tool. Also, tags should not be covered by metal that interferes with the tag’s performance. 

Tools with embedded tags

Tool manufacturers are increasingly activating in offering tools with RFID. Manufacturers have started to provide tools with RAIN RFID tags integrated into the tools at the point of manufacturing. Embedded tags will eventually eliminate the tag attachment process steps.

Different tools with embedded RFID tags.
Tools with embedded RFID tags. 

Why is testing the RF performance of the tagged tools important?

Realizing the full benefits of using RFID in tool tracking requires that the application works as planned – in other words, the RFID tags on tools are read and detected accurately and reliably. RFID tags designed for tools are optimized to work well on metal items and specific form factors. However, the RF performance is always affected by the object it is affixed to and how it is positioned towards the reader. Testing the RF performance of the tags is important to ensure reliable and consistent read ranges and to help choose the best tag for the application. It will be difficult to design a reliable tool-tracking system if there is a high variance in the tagged items’ read ranges.

Testing the performance of a RFID tagged tool.

If you would like to learn more about testing the performance of the tagged tool with Voyantic Tagformance Pro, watch the webinar recording from 25:00-33:48.

Some of the key takeaways from the performance testing presentation included: 

  1. Ensure the correct testing setup: Adjust the reference tag position and orientation to match the tool tag position
  2. The threshold sweep test reveals the maximum read ranges for the tag and the tuning of the tag – to which frequency range the tag is optimized for.
  3. The orientation sensitivity of the tagged tool reveals how well the tool can be read from different angles. 
  4. The Tagged-Item Grading tests reveal whether the tagged-items pass pre-defined performance criteria, for example, if the tool passes the same grades as the end-users currently used tools, providing good information for the RAIN RFID system designers and end-users when adding new tags to the system. 
  5. The performance of the RFID-tagged item should be well documented to help systems designers and end-users!
  6. Testing the tagged tools’ RF performance on the production line is critical when tools are tagged in volumes!
RFID tag's performance testing with Voyantic Tagformance Pro.
This orientation sensitivity test revealed that the tool can be read well when the tool’s long side faces the antenna. When the endpoints are facing the antenna, the read range drops dramatically.

Considerations for the Tracking System Features 

The software component of the tracking systems is equally important to the capabilities of the RFID tags and reader hardware. Especially when tools are tagged and traced for compliance and safety applications, the software platform needs to have the right features to handle the workflow and process requirements. Use cases are unique in many cases, but some of the main considerations include:  

  1. Process Automation – For example, if a tool is missing or misplaced, or due for maintenance or calibration, the software component of the system must be able to alert the right individuals at the right time. For real-time operations, seamless workflows are the key to realizing the system benefits. 
  2. Data management features – How data is managed and added to the database, what information can be included, and how data is configured and managed.
  3. Robust user and rights management – Employees from different functions in the organization often need to access the same system. For example, the tool users and people responsible for maintenance do not need to access the same features as the system administrators. 
  4. Location management – If real-time location is required, the software must provide the functionality for configuring locating applications and timely information based on the item’s location. 
  5. Workstation requirements – Does your application require a fixed station with self-service kiosk features for processes such as checking tools in and out or auditing the available tools?
  6. Requirements for mobility – how is inventory management done? Is there a need for hand-held readers and mobile workstations? 

If you would like to learn more about tracking and tagging tools with RAIN RFID, watch the webinar recording or contact us with any questions. And be sure to sign up for our blog updates!

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RAIN on Metal – How to Test the Performance of RAIN RFID Tag on Metal Plate

May 31, 2024

About the author

46Bill Hsieh

I am a Technical Support Engineer at Voyantic, with over 12 years of experience in RFID technology, including both HF and UHF applications. I specialize in helping customers troubleshoot issues with our products and providing timely support to ensure their operations run smoothly. My role also involves conducting product training and guiding customers in using our solutions effectively.

Content

Although RFID and metal can be a challenging combination, tagging metal items with RAIN RFID will work as well as any other application, if you choose the right kind of tag designed for metal, and also plan the system and infrastructure carefully. On-metal tags are commonly used in industrial settings, where they need to endure harsh conditions and have reliable performance and readability. It’s great to see how the rapid development in specialty tags helps RAIN RFID usage expand in industries outside of retail. 

We often get asked for advice on testing tags on metal and other materials. So I decided to make an application note on how you can use Tagformance Pro to measure an on-metal tag attached to a metal plate, both inside and outside an anechoic chamber. I will also discuss the impact of the measurement environment on this application. The interesting question is to see how the performance of the tag change when attached to a metal plate, and how much the form factor of the metal plate has an effect.

In the tests, I used the Voyantic Tagformance Pro system and tested Confidex Silverline Blade printable on-metal labels with four different size metal plates.

The confidex tag used for testing

Download the Application Note for the Results and Method

To see the full measurement results and learn how I conducted the measurements, download the application note:

Download the Application Note

Key Findings

To intrigue your interest in taking a closer look at the application note, let me share some findings:

An on-metal tag on a metal plate is highly sensitive to the testing environment, especially outside of the chamber with external RF interference. Testing in an anechoic chamber is thus something I highly recommend for consistency in results.

What do you think? Are these results measured inside or outside of the C50 chamber?

Secondly, the size and shape of the metal has effects on the performance, thus making tagged-item testing a recommendable step for any metal item tagging project.

Setup for testing outside of the anechoic chamber.

Let us know if you have any questions about the application note or using Tagformance Pro for tag and tagged-item testing. We’re always happy to help.

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EPC Gen2 UHF RFID Standard v3 – What’s Changed and Tips for Hands-on Testing

Mar 04, 2024

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32Voyantic Marketing

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EPC Gen2 UHF RFID standard v3 update was recently published by GS1. The new version came with optimizations in the air interface and new commands aiming at saving time, improving accuracy, and making the inventory process more robust. In this blog, we’ll walk through some of the most significant changes in terms of inventory performance, and provide pointers on how to get started with testing and learning yourself.

More time (and power) for the chip initialization

The minimum carrier time before the first command has been increased from 1500us to 2500us. The change comes with a small compromise on total initialization time but also works for the benefit of chips which require more time to initialize. The delay is likely small enough to go unnoticed in most applications and the extra time should secure the proper initialization of all chips. Moreover, interrogator power-up is required to be faster (500us → 250us) with more allowance for undershoot and overshoot (+/-5% → -10/+20%) during the 1ms waveform settling period. The shorter rise time is unlikely to influence chip performance significantly and the greater allowance for overshoot opens up an interesting possibility to provide a short carrier level boost (1.58dB/1ms) as part of the field initialization. This kind of boost won’t change the active state operating voltage of the chip but might help them to further optimize their performance during initialization process, and ensure optimal performance of tags.

Fig. Interrogator power-up is required to be faster, but field strength is allowed to undershoot/overshoot by -10%/+20% during the 1ms waveform settling period. The total time before command was increased to 2,5ms. Source: https://ref.gs1.org/standards/gen2/3.0.0/

Field-strength adjustment filters out fringe tags

The third update on the air interface is to allow interrogators to perform field strength adjustment during Select, Challenge, Query, or QueryX commands in an attempt to prevent ghosting tags from slowing down the inventory process. Ghosting tags, also referred to as fringe tags, are tags that have such a low operating voltage, that they might get activated and respond to Query, but do not have enough energy to follow through the response to Acknowledge command. Such tags cannot be inventoried, but since they will reply to Queries, more iterations are required in the inventory process, and the time to complete the inventory cycle gets increased.

The interrogator performs the field adjustment by dropping the carrier level by 0-20% (0-1,93dB) for the duration of the command modulation. The level is adjusted down at least 500us (RF Adjust lead time) before the start of command and brought back up monotonically at the end of the command. Tags are required to tolerate such a waveform pattern and guarantee that the minimum power needed to complete the response to Acknowledge is not more than 1,93dB higher than the power needed to start replying to QueryX. In effect, with the field adjustment in use, the tags shouldn’t have enough power to respond to the adjusted Query/QueryX command unless they’re capable of replying to Acknowledge as well, which reduces the unnecessary overhead from the inventory process.

Fig. Field-adjust before Query/QueryX (upper) and after Query/QueryX/QyeryY (lower). Field-strength adjustment can be used to bring Query sensitivity closer to Ack sensitivity which may help reduce ghosting tags and improve inventory efficiency through the reduction of unnecessary iterations. Source: https://ref.gs1.org/standards/gen2/3.0.0/

New commands further improve filtering and allow simpler memory access

QueryX and QueryY, combine classic Select + Query commands in a single timed package. Unlike Select(s)+Query, they’re effectively packaging the whole series of Selects and the following Query into a single command frame. This blocks external readers from interfering with the filtering process and makes the inventory process more robust. It also prevents tags from participating if they only heard part of the QueryX/QueryY command frame. This could be the case if they’ve been moving in/out of the reader’s field of view during the inventory cycle. Lastly, the new commands come with optional configurations such as an option to choose whether the tag shall include EPC or TID into the ACK response (AckData), whether RN16 is protected with a checksum (ReplyCRC), and flexible filtering conditions: ≥, ≤, ≠, = (Comp). These parameters add flexibility to the inventory process and can be used to make the process more efficient.

Fig. QueryX/QueryY commands effectively package Select(s) + Query into a single command and provide new parameters for more efficient and robust inventory process. (click to enlarge image). Source: https://ref.gs1.org/standards/gen2/3.0.0/

ReadVar, is an alternative to Read (which also remains mandatory in the standard). The two are very close to each other, but the tag reply to ReadVar contains additional informative data. NumWords indicates number of words returned as part of the reply, MoreWords indicates the amount of data yet available in the memory to read beyond the read space, and there’s a parity bit computed over data transmitted (Parity). Overall, ReadVar command is more flexible in comparison to Read and makes tag memory access easier as the user doesn’t need to know the available memory size of the bank targeted.

Fig. ReadVar is a more flexible version of the classic Read command.
Source: https://ref.gs1.org/standards/gen2/3.0.0/

Use custom commands to test new protocol features

Tagformance Pro comes with an option to utilize user-defined custom commands in tag performance tests providing a practical means for testing some of the new Gen2 v3 features. Custom commands can be created using a standard text editor, imported to the software, and used in the performance test programs. For example, it’s possible to generate a custom Query command waveform with field adjustment and testing the effect on tag performance using Threshold sweep (see figures below). Furthermore, a custom command can also be combined with ISO 18000-63 inventory into a custom command sequence, which allows preparing e.g., ReadVar test command.

Fig. Custom command feature allows generating used-defined command waveforms which can be utilized in standard test programs, such as Threshold sweep. (Left) Normal Query waveform Query, (right) Query with field-strength adjustment and 500us RF adjust lead time.
Fig. Measurement example – Query threshold with and without field adjustment. Read sensitivity threshold provided as a reference to give an idea of difference of Query vs. Query+Ack sensitivities of the tag tested.

For more information on the updates discussed in this article and other important changes in the protocol, go to the new version of the protocol on GS1 official website. Of particular interest might also be Snapshot sensor reading procedures which were mainly mirrored from ISO-18000-63. Also, remember to check what’s new in the Tag data standard to stay current with the latest changes in the tag encoding.

Download – Example Custom Command Package ›

Presentation – Extend Tagformance Testing Capability with Custom Commands

Download a quick overview on Tagformance Pro Custom Commands feature including application examples.

Download
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Testing Tags for ETSI EN 302 208

May 05, 2023

About the author

21Jesse Tuominen

I joined Voyantic as a partner in 2005 to design Voyantic's first commercial product, and I've had a front-row seat since then to see how the RAIN technology has evolved and matured while bringing my own contribution to it. As a background, I have a MSc level in electronics after which I made my PhD in the field of photonics. UHF RFID slots nicely between these two worlds and they offer a lot of perspective into my work. Currently, as the CTO of RFID technology, I work with new measurement methods, RF design, proofs of concept, standards, protocols, industry collaboration and IPR.

Content

We are getting a fair amount of questions on “how to approach ETSI EN 302 208” and I figured I would first give you all the painful details and then summarize what I believe is the right advice. My message is: EN302 208 testing can be made really fast and easy. Read on to find out how!

A bit of history

Right from the early days of the European Union and the UHF band RFID, the “EN 302 208” has been the well-known and unified standard describing how to set up and test RFID equipment to be declared as radio devices in Europe.

The first version was published back in 2004 describing reader requirements, but also briefly touching on the subject of RFID tags by setting a limit for their out-of-band spurious emissions. Most probably this was taken more as input by reader designers to limit Back Link Frequency (BLF) in their ETSI mode, and not really as impacting the work of tag designers. After all, it’s the reader that sets the carrier frequency, and power level and has command over all of the tag’s settings, right?

Well, nine standard versions later we are now at v3.3.1 which has limits for both tag out-of-channel emissions as well as outright limits for backscatter levels both for the ~865 MHz “lower” and ~915 MHz “upper” band ETSI channels. In the last few years, tag manufacturers’ interest to produce and offer labels fulfilling the standard has steadily grown. Most probably as a result of RAIN technology entering new market verticals with longer and stricter traditions of following all kinds of standards.

Feels a bit complicated, why is it so?

The standard has been a tough one for tag manufacturers to decipher as it is written in the form of a traditional EMC standard talking about power spectral densities, transmit masks, and resolution bandwidths.

This makes it harder to compare the limits against more typical RFID tag results that we have gotten accustomed to, such as “power on tag reverse”. However, the greatest layer of fuzziness comes from the fact that the standard is a generic standard, as it understandably needs to be, providing absolutely no help in associating the tests with RAIN technology, GS1 Gen2 protocol, and the equivalent ISO counterpart 18000-63 that 99% of all the UHF tags utilize. This unfortunately leaves a lot of room for interpretation.

The actual test to be performed, according to the standard, sounds relatively straightforward: 1) Radiate the tag by a field strength equivalent to 2W ERP from 20cm away. 2) Record the tag’s modulation spectrum. 3) Compare against limits. Well, a tag doesn’t backscatter anything on its own unless a proper command is given. So, a command is needed in the form of Query, Query+Ack or Query+Ack+ReqRN+Read. For the lower band a BLF of ~300kHz should be targeted and for the upper band ~600kHz. In Gen2, these in practice will often be rounded up to 320kHz and 640kHz as those are the frequencies that all tag ICs can divide their clock down to. The problems arise trying to capture the tag’s response with a spectrum analyzer. The response is always very short, typically only a few hundred microseconds and inconveniently only some 30 µs apart from the immensely more powerful command itself. Accidentally analyze any part of the command or any part of the silence after the tag’s answer and the outcome will be hugely incorrect.

So what is left for interpretation?

According to the standard, the answer should be recorded with a resolution bandwidth of 1kHz around the carrier frequency. This indirectly implies that the answer should be much greater than 1ms for this to be even theoretically possible. So, the exact correct resolution bandwidth can rarely be used except for some high Miller modes in combination with the lower ETSI band’s lower BLF.

This brings us to the perhaps biggest question: Which modulation type and data content should be used in the tests, and is the test supposed to be passed for all of these modes, a typical one, or for any selected single mode of use? The difference in passing or failing the test can be as big as 15 dB between these several modes! In simple terms, a tag that always modulates with a fixed amplitude between the same two impedance states while backscattering will always produce an equal amount of total backscatter power. What is different, is how spectrally spread or focused this power will be. And for the ETSI test, what is recorded in the end, is the strength of the peak spectral feature. So, it will be much easier to pass the test with the power spread across the frequencies as evenly as possible. 

Let’s compare the spectra

The absolute worst case for the ETSI tag emission test will be a “continuous square tone”. That is, a symmetric square wave modulation as in the case of sending a long train of data zeros with FM0 decoding. The same square wave modulation also happens in the miller modes when the extended preamble is requested by the reader. The square-wave backscatter modulation of the tag will create a Fourier-series type of spectrum with almost all of the power concentrating on exactly carrier +/- (n*BLF), where n is an odd integer. This is the absolute most difficult mode to pass the test with and that’s why in the Tagformance system this is referred to as the “worst case” from release version 13.5 onwards. Pass this and you will pass everything else too with no need to test for anything else.

Comparison of spectra of equal power backscatter signals with different coding type and data content.

Ironically, if FM0 is the “worst case” to pass, it is also the “easiest case” when the packet data is randomized. Having a roughly equal distribution of zeroes and ones in random patterns will with high probability create a very spread out spectrum. A spectrum with no predictable high peaks which could breach the mask and fail the test.

Somewhere between the worst and easiest cases fall all the Miller modes producing their tell-tale double-peak “rabbit ear” spectra. Miller modes, ranging from M2 through M4 to M8, are often favored by the readers for their decode sensitivity. This is why we have chosen the M4 with a randomized data packet to be our most “typical case” for tag emission testing.    

The Voyantic way

Currently, Voyantic offers two approaches in the Tagformance system to test for tag emissions. The perhaps more traditional and thorough approach makes use of a separate calibrated Rohde-Schwarz spectrum analyzer which is synchronized to the Tagformance system to record just at the correct moment and for the correct duration to hit the tag answer.

The alternative method is the “simulated spectrum” method, as it is referred to in the Tagformance user interface. Despite its name, it is a tag measurement, where the tag backscatter is measured for amplitude and frequency. The point where a measurement turns into a simulation is when the measured parameters are taken to recreate a prototype of a waveform, the spectrum of which is then evaluated against the mask limits. The simulation assumes a sharp backscatter modulation between two discrete states utilizing a random data packet which is selected to be as average and representative as possible. This is very close to reality, and what is important, is that the reality can only be more forgiving. So, if you pass with the simulation, you will pass in the spectrum analyzer measurement too. The great advantage of a recreated data packet is that it can be created to be of any suitable length and thus analyzed with any resolution bandwidth.

A simulated backscatter spectrum in relation to the ETSI limit in Tagformance. A finer ResBW of 1kHz is used in the central 2MHz according to the standard.

Conclusion

An easy option is to take the EN302 208 testing as a part of the design process as the testing can be made really fast and easy. It is adequate to use the simulated mode as in reality, things are not going to be worse. So if you pass, you pass.

This really means that the measurement system and setup are exactly the same as you would use for tag measurements.

Using Tagformance Pro and a Voyantic measurement cabinet, the result is just a few clicks and a few seconds away at any given time. Simply place the tag on the measurement platform as you would with e.g. threshold or read range measurements and run the tag emission test.

Finally, Just wanted to take this opportunity to mention that our C50 cabinet has a really nice very-low-echoic rotation system, and having a Tagformance Pro and C50 on one’s lab enables truly complete measurement capabilities from basic frequency response (threshold, read range) measurements to EN302 208 and ARC pre-testing. All in one system, easy to buy and use – and to maintain for several years to come.

Ah, one more thing, get the latest version of Tagformance Pro UHF software to have the well-recommended “typical” simulated results at your disposal! No spectrum analyzer? No problem!

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Hospitals, Logistics, Automotive,… RAIN RFID is Everywhere – A look into RFID Research in 2022

Jan 03, 2023

About the author

15Teemu Ainasoja

I am Sales Director at Voyantic. I have over 15 years of experience from the RFID industry in Europe and the USA. I have two master's degrees: in industrial engineering and in marketing, and two patents in auto-ID technology. I am actively participating in RAIN RFID alliance activities.

Content

It’s a new year and, again, a time to take a look at what’s been published in RFID research in the past year. I have done these yearly recaps a few times now (see posts from Jan 2022 here and from Feb 2021 here) as looking at the research field gives a good indication of what might become available for business applications in the coming years.  

Numerous RFID-related themes and topics were researched in 2022. Some popular themes were again sensor tags and healthcare applications. The RFID industry has grown strongly and that growth may have boosted research topics that are very close to practical implementations.

Advances in RFID Sensing

Sensor tags continue to be a popular research theme within RFID. Temperature is the most popular physical property being measured. Temperature sensing is followed by humidity sensing and pressure sensing. RFID sensors are being studied, for example, in pharmaceutical and food logistics applications.

RAIN RFID is used widely in tracking applications in logistics. Expanding the use of existing processes and infrastructure to also monitor freshness seems like a smart addition.

RFID sensing is not limited to the major physical properties. In 2022 many countries have seen energy prices soaring. 

RFID Sensing in Healthcare

Non-invasiveness of RFID is a driver of the study of healthcare applications. Researchers from University Tor Vergata have published studies of several applications such as:

Research Assisting RAIN RFID Implementations

Some research papers are tightly connected to RFID implementations, solving practical problems that have occurred.

RFID could be used to monitor underground pipes for corrosion and leakage.

The Voyantic Tagformance system with anechoic chambers has been used as a measurement and testing tool in many of the RFID research projects. Publications of several RFID research projects utilizing the Voyantic Tagformance system can be found at Google Scholar. Stable and purpose-built RF test conditions ensure reliable results in academic and commercial research projects.   

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Tagformance Pro UHF 13.3 Released

Nov 15, 2022

About the author

25Voyantic

Content

The latest version introduces new features that improve testing efficiency, expand configurability for the tests, and introduce a new JSON result file format.

Voyantic has released new software and firmware versions for Tagformance Pro UHF and Tagformance Pro HF. The new versions are available for download for existing customers with Tagformance version 13 and for all customers with an active Support & Maintenance contract.*

Change log:

  • New fail-fast mode saves time with TIPP and ARC measurements by skipping tests where a result is not possible
  • ARC test: Y specification added
  • Custom command waveforms: control over timing and modulation depth
  • JSON file format
  • NOTE: Tagformance Pro HF users need to update the software too

Fail-fast Mode Saves Time with TIPP and ARC Measurements

Tagformance 13.3 release introduces a new feature to the Tagged-Item Grading System and ARC Pre-compliance testing. The new “fail-fast” test mode option skips unnecessary tests which are bound to fail, saving valuable testing time. For example, if there is an angle where the tag does not reply at all, the rest of the test for the given cell is simply skipped after the first failure. This is particularly useful when testing for all TIPP grade or ARC categories.

The 13.3 version also adds support for the new ARC Y-specification.

Custom Command Waveforms: Control over timing and modulation depth

V13.3 adds new options for custom command waveform generation with control over timings and modulation depth, plus a configuration possibility for ISO18000-6C link parameters. These will add more flexibility for testing and enable new kinds of test scenarios, such as emulating filtered modulation signals.

JSON File Format

The new release also introduces a new result file format that will replace the TFF format in the long term. The new JSON result file is more machine-friendly and allows programmatic post-processing of results, as well as more flexible management of metadata. The old TFF format is still available as a legacy option (import, export), but JSON is the recommended default export format.

Voyantic Tagformance is used in UHF and HF RFID tag design, deployment, item tagging, protocol testing, technical sales, and academic research. It is the industry standard solution for RAIN RFID and NFC testing and measurement.

Schedule an online demo to learn more ›

*V13.3 requires V13 license. Contact sales@voyantic.com for assistance.

Note: Tagformance Pro HF users will need to update the software too.

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RFID for Challenging Environments – Durability Considerations and Environmental Standards [Webinar Recap]

Jun 21, 2022

About the author

32Voyantic Marketing

Content

A couple of months ago, we held a webinar that addressed different environmental standards and durability requirements for RAIN RFID and NFC tags used in challenging conditions. The webinar also covered how tags typically get damaged, how damages in the inlay affect the performance of the tag, and how the durability of the tags can be tested. Our guest expert for this webinar was Richard Aufreiter from HID Global.

Watch the webinar recording ›

In case you missed the webinar and would just like to hear the main points, read on for a short recap and links to more information.

What Breaks an RFID Tag?

As a starting point for diving into the durability of RFID tags, knowing the RFID tag structure helps understand where the breaking points are and how a typical label tag can get damaged without a protective hard shell.

Typical retail hang tags can be easily bent and damaged.

An RFID inlay consists of an IC, an antenna, and the bonding between the IC and the antenna. This inlay structure is what creates the RF performance of the tag and in practice the read range and the reading angles. The rest of the tag components are non-RFID components, e.g., the baseliner, the label surface materials, the hard case, etc.

RFID tag structure

The typical part that has the most effect on the performance, and is also the most likely spot to fail, is the bonding glue between the IC and the antenna. When the tag is bent, it creates stress in the bonding glue and as a result, possible microfractures that can advance gradually in continuous use and deteriorate the tag’s performance also gradually. A damaged tag needs more power to work affecting the read range and causing tags to fail.

Bending and stressing the tags affect the read range of the tags

Tag inlay models have differences in durability and testing is a good way to find the most suitable design for different use cases.

Learn more about durability testing methods ›

Another reason for a tag to fail is a cracked IC. And when the IC crack, the tag typically stops working completely.

The third component of the RFID inlay, the antenna, can also get damaged. A damaged antenna typically does not completely stop the tag from working, but it affects the tuning and the sensitivity of the tag when the geometry of the antenna changes.

A disfigured antenna

The non-RF components of the tags can also get damaged, but those damages do not typically affect the RF performance if the inlay is still intact. The damages can be cosmetic, for example, damaged print on the label. The attachment of the tag to the item can also get damaged, or the hard case of the tag may break.

RFID Tag Durability Standards in Harsh Environments

Some RFID use cases require the tags to endure harsh environments and handling. Tags may need to endure extreme temperatures, high pressure, impacts, vibration, water, etc. Examples can be found in the typical use cases of logistics, life-cycle, and inventory management, and in various industries, for example, manufacturing, hospitality, healthcare, logistics, aviation, etc.

During the webinar, Richard introduced various challenging environments, applicable standards, and testing methods for those environments. There are not necessarily standards available for all the different environments and use cases, but the suitability of the tag for the specific challenging environment should be verified with testing, nevertheless.

Watch the webinar ›

The typical RFID use cases for harsh industrial environments include logistics, maintenance, life cycle management, and inventory, both indoor and outdoor. Things like washing, exposure to chemicals, potential impacts, and extreme temperatures make these environments challenging.

Below, I listed the environmental standards covered in the webinar. Not every use case or environment has a dedicated certification or a standard, but the unique requirements posed by the environment should always be considered.

Yard Management in Rugged Environments

Items kept in stock need to be identified to make sure you have accurate inventory and to verify you take the right items. The tags may need to endure vibration, impact, and pressure when tagged equipment is being moved and may hit other objects in the process. Tagged items may include things like drilling pipes, shipping containers, and other heavy objects.

Vibration durability can be tested with a rattling table. Testing makes sure there are no parts inside the tag that get loose or damaged the chip or the antenna or break the housing of the tag.  Pressure is also tested to make sure the housing doesn’t break. Metal housing can make the tag highly impact resistant.

See a video of HID’s tag testing ›

Related standard;

  • Impact Resistance: IK rating defined in EN62262, measured in Joule

Explosive environments

Explosive environments can be found, for example, in the oil and gas industry and the mining industry. In explosive conditions, tags need to be safe to use and should not cause an explosion due to overheating.

There are two certifications that apply to explosive environments:

  • ATEX (European)
  • IECEx (global)

ATEX defines zones based on how explosive the environment is and what the tag needs to endure. Both certifications are more relevant for devices that are powered and not so much for passive tags.

Extreme Temperature Environments

An example of an extremely cold environment can be found in healthcare, where medical sample vials may be stored in liquid nitrogen. If you want to tag the vials with RFID, the tags must withstand that same temperature and also be readable.

On the other end of the spectrum is flame resistance. One example use case Richard mentioned during the webinar was a tag designed to be used in an aircraft engine. A flame-resistant tag will not ignite when hit by a flame and will not burn by itself after the flame is removed.

Applicable Standard for Testing:

  • UL94 HB = IEC 60695-11-10 (former ISO 1210)

Washing Environments

Washing is a very common use case. There are different levels of washing resistance. Tags need to endure anything from a splash of water to long-term underwater submerging and high-pressure power washing. The IP rating developed by the IEC defines the level of water resistance depending on the use case need.

Relevant ratings:

  • IP 66, 67, 68, and IP69K for power washing

Chemical Exposure Environment

Chemical exposure resistance also starts with waterproofness, but tags need to also endure the effects of chemicals, for example, detergents in laundry applications or sterilization in the healthcare environment. The standards for laundry are not RFID specific but they ensure that tags on textiles are safe to be used and do not pose a health risk.

Relevant Standards:

  • Laundry Testing / Tags on Clothing
    • ISO 15797 for the workwear washing process
    • OEKO-Tex® for certifying there are no harmful substances for human health
  • Medical healthcare environment
    •  MR – using a tag inside a magnetic resonance inspector with strong magnetic fields. The antenna cannot cause any sparks.

UV Resistance

Some plastic materials are sensitive to UV light. UV exposure from the sun and other light sources can lead to discoloration and hardening of the plastic. UV resistance can be tested in accelerated weathering tests where the item is put under extremely strong UV light that simulates a longer time frame in the real environment.

Relevant standard:

  • ISO 4892-2 (Weathering)

Learn more from the webinar

One of the key takeaways from the webinar is to understand the use case and the unique factors that determine which tag is optimal for the application – defining the tag frequency (LF, HF, UHF), IC capabilities, and the tag fixing options.

Check out the webinar recording for a handy reference on the main characteristic of different RFID technologies, and example use cases with different tag types. During the webinar, we also covered tag durability testing method examples from the Aerospace and the tire industry.

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The “Secret” to Ensuring Accuracy and Repeatability in RFID Testing – Properties of an RFID Test Chamber

May 17, 2022

About the author

21Jesse Tuominen

I joined Voyantic as a partner in 2005 to design Voyantic's first commercial product, and I've had a front-row seat since then to see how the RAIN technology has evolved and matured while bringing my own contribution to it. As a background, I have a MSc level in electronics after which I made my PhD in the field of photonics. UHF RFID slots nicely between these two worlds and they offer a lot of perspective into my work. Currently, as the CTO of RFID technology, I work with new measurement methods, RF design, proofs of concept, standards, protocols, industry collaboration and IPR.

Content

When our customers think of where measurement accuracy and repeatability in a tag testing setup originate from, they usually mention things like output power resolution, power setting accuracy, measurement distance measured down to a millimeter, angular alignment, and high quality matched antennas, test grade RF cables, etc…  My claim is, and it’s not even a bold claim, but more like a friendly reminder, that the most significant factor in achieving result repeatability and comparability is actually the environment.

So, what is the best route to a great environment? Well, clearly, the best solution is to use a closed and controlled environment like an anechoic cabinet specifically designed for RFID measurements. At Voyantic, the most iterated and refined cabinet is the C50. It is also the smallest of the offered cabinets, supporting the TIPP/ARC compatible four antenna measurement layout.

  

ARC / TIPP antenna arrangement and the C50 cabinet

Test Distance

The C50 name comes from the 50cm nominal measurement distance and the circular arrangement of the antennas. The choice of the distance is a sweet spot to be as close as possible for best accuracy and dynamic range, but far enough to be in an accurate enough representation of a  far-field for most average-sized tags, tagged items, and item stacks. Any further attempt to still reduce the distance rapidly ends up in the antennas not physically fitting anymore or just coupling into each other as they would sit in each other’s reactive near field.

The Cabinet Size

When you add on top the 50cm test distance the size reserved for the test object, clearance for the Fresnel zone, the volume required by the UHF range pyramid absorbers optimized for each wall, and the outer shielding, you still actually end up with a reasonably sized package. The C50 chamber totals to dimensions of 1,55m x 1,50m x 1,05m. This typically doesn’t sound important in any way, until one is planning the location for the cabinet and the transport route up to the very spot. These dimensions have not evolved by accident but rather designed from experience so that the cabinet would fit through as many door openings, narrow corridors, and elevators as possible. Also, the total weight remains in the 200kg range, making it movable by a few sturdy RFID test engineers without renting any additional equipment.  

A Sturdy RFID Engineer

Low Reflections

One of the hardest parameters to get right is the level of unechoicity. It wouldn’t be too hard in a totally empty space, but as the item under test requires a computer-controlled rotatable platform withstanding over 10kg of weight and still being totally stealthy, things get a lot trickier. The rotation mechanism and the support platform should not provide alternative radio paths from the antenna to the tag which could create a multipath situation and decrease the accuracy.

Turntable Design

To achieve the required stealth properties, anything bulky, parallel, and flat should be avoided. Also, electrically conductive materials must be avoided at all costs, except for the shortest of screws.  This means that conventional mechanical design is thrown right out of the window and other approaches are needed. Our chambers have fully ceramic bearing structures, Kevlar belts, fiberglass axles, Nylon bolts, and numerous foam structures. Most other structural parts are carefully designed from polyamide with most of the material hollowed out and any parallel and straight lines broken to reduce the RF footprint as much as possible.

Components in the chamber are designed to minimize any RF reflections.

See the full range of available Voyantic anechoic chambers here ›

Is your RFID lab up-to-date? Download R&D Solutions Catalogue

Learn more about the Voyantic Tagformance® Pro system, accessories, and test chambers!

By combining RAIN RFID and NFC testing into one compact test device, our all-new Tagformance Pro is a true all-in-one tool for anyone either developing or using RFID technology.

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Adaptive Front-Ends Are Here to Stay

Jun 30, 2020

About the author

21Jesse Tuominen

I joined Voyantic as a partner in 2005 to design Voyantic's first commercial product, and I've had a front-row seat since then to see how the RAIN technology has evolved and matured while bringing my own contribution to it. As a background, I have a MSc level in electronics after which I made my PhD in the field of photonics. UHF RFID slots nicely between these two worlds and they offer a lot of perspective into my work. Currently, as the CTO of RFID technology, I work with new measurement methods, RF design, proofs of concept, standards, protocols, industry collaboration and IPR.

Content

中文版 Chinese version

Impedance Matching

Matching the transponder antenna well to the chip impedance has always been the cornerstone of a well-performing UHF tag. For antenna designers, it is lightly frustrating that each chip brand and model seemed to have their unique impedances, therefore various versions of the same antenna are needed for different chips models.

On the other hand, from the chip designers’ point of view, it must have been frustrating that the tag antenna is never comfortably operating in free space, but always attached to various materials needing different tuning to operate optimally again.

For a long time, it has been known that impedance tuning does not need to be a permanent compromise, but can be actively re-tuned. This has been the norm in many wireless communications and roughly ten years ago this was introduced to UHF RFID as well. The first company to open the game was RFMicron with their ”Chameleon technology” in the Magnus® family of chips.

The early chips had a 5-bit tuning register, giving 32 different and successive tuning states, wherefrom the chip chose the optimal. Since the register value could be read back, the biggest value proved not to be the improved tuning, but the information of how much was tuned. This was turned into a clever way of performing RFID sensoring and later chip versions had an improved resolution of a 9-bit tuning register.

Today, several mainstream RFID chip providers utilize self-adapting front-ends for the small performance gain it provides. Most notable companies utilizing this are Impinj and NXP. Here we are going to see how this alters the tag performance and how to gain visibility into this.

Visibility Into Tuning

First, let’s take a look into the Monza® R6B chip. Examining the memory map in the datasheet, it clearly tells that there are three bits in the reserved memory where you can read the current suggested tuning state. In addition, there is a single bit, by which adaptive tuning can be disabled.

Part of the Monza® R6B datasheet

So, to set the feature on or off in Tagformance® for testing, the simplest way is to perform any write test with the correct write parameters. Reserved memory, Word pointer 4, and write the last bit high/low to deactivate/activate the tuning. The current state can be verified by reading the same memory.

Write parameters for turning the adaptive tuning off. The memory map of the Monza® R6B reserved memory showing the change (in red) where the disable bit was activated. Read parameters to point to the three tuning bits to read back the current tuning state.

Below is a threshold of the tag both with the tuning activated and disabled. With the adaptive tuning activated, the area of optimal performance is seen to increase by +/- 10MHz for this particular inlay design. To monitor the used tuning state, do the sweep with the READ command and the correct read settings for the chip. This gives the ability to select “response data” from the drop-down menu to see what data the chip responded with to the READ. In this case, you can see the tuning goes from 4 to 0 in the ~20MHz stretch from 880MHz to 900MHz.

Sweeping a tag using a READ command while monitoring the tuning state.

How About the UCODE®?

The UCODE® 8 family from NXP works in quite a similar manner. The tuning state can be read back from the memory by pointing to the correct location as stated in the datasheet. The deactivation of the feature needs more involvement. It seems a non-zero access password needs to be set for the tag, and then the setting bit needs to be “toggled” in the secured state using the proper WRITE command as the BLOCKWRITE will not do it. As the UCODE® has fewer tuning steps, you can sometimes spot from the tuning curve the points where the impedance was changed. It’s as if the curve consists of a few cut-n-pasted curves. Well, because it kind of is.

A close-up of a threshold sweep of a UCODE® 8 based label revealing the discrete tuning steps.

Conclusion

Automatically adaptive tag ICs are here to stay. It might be that the advantage they provide is a little slim at the moment, but if there is a performance gain to be had, why not take it? For the antenna designer and tag producer, it is valuable to be able to also switch the tuning off when needed, to easier judge the antenna itself, perhaps against a simulation.

Alternatively monitoring the read response data “stepping diagram” is a simple tool to see if the design is functioning as it should. Eager to chat more about tag design with us? Feel free to contact our RFID experts HERE.

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