RFID tags are not like bar codes. Just because you see a tag doesn't mean your RFID equipment will see it. Contrarily, if you can't see a tag, it doesn't mean your RFID equipment won't read it. Confused yet?

In order to have a successful implementation, it's important to understand the basic concepts about RFID tags, tag placement, and to take the time to consider how tagged assets and are going to be identified and tracked. If you're implementing in retail, logististics, or transportation operations, that means understanding the complex journey of a product from manufacturer to store and the different ways a tag's readability may be affected. You must choose your real-estate wisely and place RFID tags with consistency. It is time and money well spent because if your tagged product doesn’t read, either your customer will catch it and charge you a handling fee, or worse yet, they won’t catch it so you’ll loose the cost of the product because your customer’s inventory is wrong, AND you’ll may even have to send a replacement product. Exception handling is far the more costly than the price of an RFID tag.

1. Environmental Considerations for RFID Tag Placement

Your customer’s and trading parnter's environment is different than yours. Yes, this is stating the obvious, but up until now, you probably didn’t care. Now, you need to care. Retailers have an extremely different design approach to their RFID solutions than their suppliers because they are dealing with thousands of companies shipping a wide range of products. Therefore, they will optimize their equipment configuration for the average product, not your specific product(s) the way you will.

While the physical layout of a distribution center and a retailer store may be similar, there are several complicating factors that can negatively impact the readability of tags. First, it's at this point in the supply chain that your product may come in contact with other products – either on a conveyor or as part of a mixed pallet. This means that your case could be next to one that includes metal or water - elements that can affect readability. Second, some retailer's distribution centers move cases on high-speed conveyors that operate at 600 feet per minute and the retailers expect tags to be read at that rate. However, few manufacturers have tested their tags on conveyors that run above 300 feet per minute.

But wait, the complications don't end there. The biggest infrastructure challenge is the retail store itself. Stores receive loose cases of products piled into the truck (like in the picture above). Once unloaded from the trailer, products may be placed on push carts, hand carried, and conveyed. The problem lies in the lack of conformity of movement. Retailers are most interested in what direction products are moving. They want to know as products come in through the dock doors, move from the backroom to the sales floor, leave through exterior doors, and finally when the case is put in the trash. Many manufacturers have only taken into consideration how cases are moving in one direction - out.

In simple terms this means that your choice of tag and tag placement must be suited for the most challenging environment, which is most likely outside your facility and scope of control. Since your retail customer has little control over what RFID tag is used and where it is placed, they are relying on you to tag products correctly.

You want to tag it right? Here’s the stuff you need to know:

What RFID Tag To Use?

Most likely, your current bar code label is going to be replaced by a label with an RFID tag in it, also known as a smart-label - like the one pictured left. The characteristics of the tag in your label are very important.

2. RFID Tag Standards

The global standards for RFID tags used with pallets, cases, and items in the supply chain are ISO-180006-C and EPCglobal™ Class 1 Gen 2, which is why our team focuses the majority of our testing on tags compatible with these standards. These two standards are extremely close to one another and interoperate without any problems. You can narrow down your shopping list by only considering tags that are certified by EPCglobal™. The complete list is published and can be found here. The certified tags come in a variety of shapes, sizes, and prices. At this point, you need to select a few different tags for testing with your products. You may decide to use different tags for items, case/cartons, or pallets. Our team has also published a comprehensive set of benchmark reports on durable asset tags.

3. In What Geographic Areas Will The RFID Tag(s) Operate?

In what geographic areas will the tag operate? Different regions of the world have different standards regulating the use of radio frequency (RF) emitting products. Standards are developed and issued by international, regional, national, and industry specific entities. For example, in the US, there's the Federal Communication Commission (FCC) and the E.U. Council in Europe; The Association of American Railroads (AAR) and International Air Transport Association (IATA) have their own standards. The more global the standard, the more entities are involved in the development. If you are tagging in the US and shipping to a US destination, then a tag suited for US FCC is fine. However, if you are tagging in Asia and shipping products to both Europe and the US, then you should consider a tag suited for international operations.

Keep in mind that the differences between reader operation in the various regions goes beyond what frequency range is used. There are differences in emitted power, how the reader hopes between frequencies, and more. It’s more complicated than many realize. To simply things a little, the below table can give you an idea of what kind of performance you can expect based on tag reader combination being used. For example, row 1 explains that a tag tuned for 902-928 (US FCC) will work best with an RFID reader operating within the specifications of 902-928 (US FCC). The tag will still work in Europe, Japan, and other regions, but its performance will not be a good as a tag suited to the region. A tag tuned for global operation should perform well across all regions.

Tag Tuning / Reader	902-928 (US FCC)	865-869 (EU)	952-955 (JPN)	Other Regions
902-928 (US FCC)	Best	Fair	Fair	Fair
865-869 (EU)	Fair	Best	Fair	Fair
952-955 (JPN)	Fair	Fair	Best	Fair
Global Operation	Good	Good	Good	Good

4. RFID Tag Size

Size DOES matter - a larger tag antenna normally provides greater read range and better overall performance. However, a 4” x 4” tag will not fit on a small bottle of medication. Consider the available space for tag placement.

5. RFID Tag Orientation

Few implementations have the ability to control tag orientation 100% of the time. In the supply chain, your product may be flipped in any direction once it leaves your facility. The tag may even end up facing down on a conveyor. Some RFID tag antennas and RFID chips are better designed for operation in environments where orientation is not controlled, such as airline baggage handling.

6. Temperature, Humidity, and Climate the RFID Tags Operate In

Be sure to note the temperature and humidity extremes that your products are exposed to and make sure that the tags you select are rated to operate within those extremes. A special coating on the label face may also be needed to resist water. More importantly, double-check the type of adhesive used to affix the tag on the product. If your tag is going to get frozen or wet, you don’t want it to come off because it no longer sticks. This topic is so important, we have a detailed article: Adhesives and RFID Tags

7. RFID Tag Memory

There are tags that have additional memory capacity that may be used to store information such as date of manufacture or expiration. Additional tag memory may be necessary in applications where needed information must be stored in the tag because it cannot be retrieved using a database lookup with the tag ID.

8. RFID Tag Reading, Writing, or Both?

Consider that there will most likely be the need for RFID tag to be encoded, or written to, during one or more processes. Some companies affix tags to items at the point of manufacture, but don't encode the tagged items at a later point in time, often after they have been packaged.

RFID Bulk Encoding

Bulk encoding can provide additional gains in ROI by allowing manufacturers to delay customer-specific encoding criteria until the end of the packaging process, when it can be done “on-demand”. The process of bulk encoding UHF RFID tagged items has both hardware and software components. When bulk encoding a packaged set of tagged items, the first (and often most challenging) step is to identify all the tags, and only the desired tags, to be encoded. Once uniquely identified, the process of encoding the tags is relatively simple. ThingMagic has written an application note you may download titled, "Designing Bulk Encoding Applications Using UHF RFID Technology".

9. Method of RFID Tag Attachment

You may affix a tag mechanically or with an adhesive, depending upon the situation. In environments that require durability, mechanical fixtures (using cable ties, screws, bolts, pop rivets, or brackets) are the preferred methods of attachment. They are more reliable and less prone to failure, especially in cases of high mechanical stress or variable/extreme temperatures. Our team has not seen an instance where the addition of metal screws or rivets has adversely impacted performance by any measurable amount.

Adhesive fixture must used when the RFID tag cannot be mechanically attached. It is extremely important not to underestimate the importance of the adhesive used to affix the RFID tag to the tagged item. If the wrong adhesive is used, the tag will become detached. We've written a detailed article here: Adhesives and RFID Tags

Certain adhesives have a known lifetime until failure. Our team recommends discussing the adhesive used with your tag provider to ensure it will meet your specific environmental (temperature ratings, impact resistance, and chemical resistance) and lifetime requirements. A quality tag provider will be able to tell you the specifics. Here are a few things to know before contacting your tag provider:
What are the composite materials to be affixed to?
What are the temperature and humidity ranges the tag will be exposed to and for how long?
Will the tag be subjected to washing and if so, what detergents will be used?

10. RFID Tag Placement: Where do you stick it?

You cannot simply place a tag wherever is convenient, and expect it to read 100% of the time. Some factors that affect tag performance are 1) the composite materials of both product and packaging (because some materials, like water absorb RF); 2) the position of products inside the packaging; 3) how cases and cartons build a pallet. Tag placement needs to be carefully considered not only to ensure performance but to prevent damage. The best results require trying different tag placements and testing the results. Consider the following:

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1) The composite materials of both product and the product packaging - Radio frequency waves can easily pass through certain types of materials; while other materials can reflect or absorb the RF. You can’t see this with your eyes, because light waves (and therefore bar-codes) reflect differently. The image to the left illustrates how your RFID reader “sees” a box with a flash-light in it. The red color means the RF waves are not passing through the product, while the green areas show strong signal. The tag will read better in the green areas than the red areas. Click the picture to enlarge it.)

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2) The position of the products inside the packaging. The picture to the left shows an open box with a DVD player in it. The metal components of the DVD player will reflect the RF waves of the tags used in supply chain operations. If you look closely, you can see there is card-board packing between the side of the box and the actual player. Since card-board is a RF-friendly material (something that lets RF waves pass through it easily), it provides a better location for the tag than the area near the metal.

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3) How products sit in the case/carton. For supply chain RFID tags, products that contain water can be challenging. Water will absorb some of the RF signal therefore making it difficult for tags to be read. The tag is less affected when there is an air gap between it and the water. Take the case of water (pictured left) as an example. The air gaps between items can be used to improve tag performance. By placing the carton tag at the top on the outside of the box, read performance is good. There are some tags that work with both far field and near-field antennas. By using a near field antenna and tag combination it is much easier to overcome the water problem.

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4) How the cases/cartons build a pallet. When cases and cartons are stacked on top of each other, it can be very challenging to read all the tags, especially with pallets of mixed goods. The picture (left) illustrates how your RFID reader “sees” through the boxes on this pallet. The darker green, the better the readability. Some cases are missing entirely, which means they cannot be read at all while other cases are white showing they are read very little. As you can see, there are areas that RF waves can not pass through. That’s why it’s important to consider RFID when building pallets. When receiving pallets, the retailers are focused on reading the single pallet tag that describes the contents. But if all of the case/carton tags can be read as well, the retailer can verify that all the products are there. One simple way to help is to have as many tags facing out as possible.

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Test, Record, Re-position, Test, Record…

Now that you know the main factors that affect tag performance, it’s time to start testing your tags in different positions. This can be a very monotonous process. The tags that you selected earlier in the process now get affixed to your products and then (hopefully) read by your RFID equipment. When you consider all the different tags, tag placements, orientations, and hardware configurations, there can be literally hundreds of different test scenarios, each with different results. (That's why we said to only select a few tags.) Ultimately, what you want to know is what tag to use and where does it go on the item, case/carton, and pallet.

Let’s look at the example pictured right - a case of deodorant (click picture to enlarge). You’ll note that when the tag is placed on the bottom right, it gets only 20%, yet the same tag placed in the top left gets a 100%. The water in the product is concentrated at the bottom and absorbs the RF signal. At the top, there is an air gap that lets the RF waves travel through.

A couple rules of thumb to remember :

• Place the tag on the exterior of packaging. It makes it easier to replace failed or poor performing tags.

• Avoid crush/fold points of the box. If a RFID tag is "slapped" on the box just as it goes out the door, and if the tag is on the crush point, the tag readability may be compromised because the antenna can become separated from the integrated circuit.


• Consider the packaging graphics. You don’t want to put a tag over instructions or other valuable consumer information.


• Club stores sell cases/cartons of products as items, so the last bullet applies here too.


• A tag will not read if it's placed on packaging that uses metallic ink.


• Don’t be afraid to redesign the packaging to be more RFID friendly. If you don’t change it, your marketing department will, eventually.

Understand Your Options for determining RFID tag placement

Now that you know about proper RFID tag placement, how do you go about doing it? There are several options:

1) Bring in outside consultants
The right RFID consultant can help you narrow down the search for the right RFID tags quickly, especially if you’re facing a deadline.

2) Use a RFID Lab
The labs have environments similar to retail customers: very fast conveyors and dock door portals. Working with a lab can help you know what kind of performance can be expected once the tagged products leave your control.

3) Tag it yourself
Do you think you can do it?

The video at the beginning of this article shows how much time and can be saved by working with the right consultant or lab. Don't forget to consider how many SKU’s you have: ten, twenty, a hundred? Determining the best tag and placement can take a lot of time.

Tag Selection and Placement : Our Step-By Step Recommendation

1) Start by examining your highest volume SKU’s and the most physically challenging SKUs (those that contain metal and water).

2) Bringing in outside expertise on tag placement to help with those products. The information provided in this article should give you enough education to intelligently interview applicants. We are also happy to recommend an expert that specializes in this area: contact us. Please be sure to mention you are looking for help with tag placement testing.

3) Work side-by-side with the experts so you can learn the techniques and eventually take on the responsibility of tag placement. This will get you up to speed quickly.

4) Even if you're working with an expert, if you’re not 100% confident about a SKU, work with your experts or send it to a RFID lab. We can also help you to select a quality lab.

Don’t forget, you’re going to need to educate operations personnel since they are the people that have to apply the tags. The importance of proper tag placement must be clearly communicated. Some companies have already implemented quality assurance measures to ensure the right tag is being put in the right place – every time. Your customer may not thank you for doing this, but at least they won't charge you - and you'll gain some appreciation of that investment.

11. RFID Tag Warranty

Every RFID tag supplier we've spoken to claims to warranty their tags. However, our team has found it is important to read the fine print. Some guarantee the tag will read, but at what distance? We've seen variances in RFID tag performance of up to a meter! Inconsistent performance between tags causes big problems in production. One of our engineers tested 250 RFID tags of the exact same model to ensure a minimum 12 foot read range. Even though all the RFID tags read, 27 of them had to be discarded because of poor performance. That's more than 10%. Consider that when looking at RFID tag cost.

12. RFID Tag Cost

A better performing tag may cost a little more, but it could result in huge savings later on. For example, if you’re debating between the 10¢ tag vs. the 12¢ tag, consider this: a 2¢ difference adds up when you consider thousands, if not millions of products, but look at what you’re paying per year for replacing lost orders. One supplier was losing $3 million per year in lost product before implementing RFID using a 12¢ tag. They tested the 10¢ tag, but it didn't perform as well. Using he higher priced tag, they only lost < $500,000 per year - a savings of $2.5 million per year. That paid for 20,833,333 tags.

We've published a lot more information on RFID Tag Costs in our Passive UHF RFID Tags & Smart Labels Buyer's Guide.

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