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'Read This': How RFID will work in metal

environments

By David Adams (SVP Corporate Strategy & Technology, TrenStar Inc.)

Published byUsingRFID.com in April 2005.

Metal containers and RFID don't mix too well, unless you know how. But they canbe tracked with RFID just as reliably as anything else if you simply apply scienceto the art of RFID implementation...

Metal containers are, among other nice things, reusable, returnable, sturdy, safe,protective, durable and "green" all you could wish for in a container. But you may bethinking that they are a pain in the tail to track and manage, and you might not be lookingforward to having to comply with mandates (environmental, HAZMAT, Sarbanes Oxley,etc.) requiring that you use them or track them. But metal containers can be tracked withthe latest in RFID technology and managed efficiently with the latest mobile assetmanagement solutions. It's just a matter of simple science.

The problemIt is true that radio waves bounce off metal and are absorbed by water at ultra highfrequencies. It turns out, for instance, that the human body makes a very good shieldagainst RFID signals because we have so much saltwater in us. Interference from metalalso disrupts the RFID signal and especially makes a challenge of RFID enabled supplychain management, an area of operations teeming with metal, liquid and harshenvironments.

Metal causes eddy currents in the vicinity of the RFID reader antennae which absorb RFenergy, thus reducing the overall effectiveness of the RFID field. These eddy currents alsocreate their own magnetic field that is perpendicular to the metal surface. Thisperpendicular magnetic field "cancels" the reader field:

Figure 1: The perpendicular magnetic field's effectSource: TrenStar Inc.

Detuning

Metal can also detune both reader and tag antenna, causing added parasitic capacitance(which means energy drain caused by the electromagnetic "friction" from the metal) and

reduced system performance. Finally, at some frequencies the energy reflected by metalcreates interference between the tag and reader. RFID in heavy metal environments canmean reductions in actual read and write rates, ranges and reliabilities far below those

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experienced in the clean lab environments of RFID pilots. But what's also true is thatproper system design and engineering will overcome most interference obstacles, and oneuse in particular has led companies to believe that this solution is worth looking into.

Tracking and managing high value, reusable mobile assets and their contents has beenone area of supply chain management that has successfully applied RFID technology in ametal environment. These mobile assets are broadly used in many different supply chainsto carry raw material, work in progress and finished goods. Examples include beer kegs,stainless steel bulk food and chemical containers. They even have some characteristicsthat make RFID an ideal technology investment for tracking them:

First, these assets are usually relatively expensive anywhere from US$75 US$2,000.

Second, often the contents of these assets are either expensive or time critical.

Third, the information generated by the RFID network can be used to better plan andexecute the distribution channel itself.

The ROI gets easierThe high value of these assets and their contents combined with the actionable quality ofthe data generated makes building an ROI on RFID much easier. RFID has demonstrablyreduced loss rates, maintenance costs, distribution costs and improved asset and customerservice. In addition, the information generated from the RFID enabled supply chain canhelp provide reduced cost of goods sold and even rapidly identify market trends.Companies can even align the costs of the container with the value stream derived fromthe investment in the container, its delivery and the technology involved. Not in pilots, butin real world, high volume, high velocity supply chains.

According to the Aberdeen Group's recent survey of 200 companies, of those that alreadyhad an RFID system in place, more than half were using the technology for asset tracking.Tracking of high value assets is considered a good RFID entry point because it can provide

the return on investment that is eluding manufacturers taking a "slap and ship" approachto RFID adoption, which means the tags are not being used for any internal application butsimply to comply with retailer mandates. However, even these companies could find andimplement a successful tracking system and find value in RFID given the right partner.

Mobile asset trackingProviders of mobile asset management solutions combine asset acquisition andmanagement services with technology including RFID to enable the discovery andelimination of hidden supply chain costs including asset and finished goods inventory,transportation costs, and product waste. These technology enabled management servicesare outsourced on a pay per use basis so that customers can offload total responsibility fora non core business function and as a result improve their customer service, reduceoperating expenses and manage assets and asset contents effectively.

Mobile asset management solution providers also offer proper RFID solution design andreliable, low cost RFID solutions that can be deployed in environments with high metalcontent. The value of RFID is generated by the solution provider from the subsequentcreation of improved business rules that drive more efficient processes and procedures.

Seven basic guidelinesBut of course you don't have to outsource management of your mobile assets. If youchoose to go it alone, for the best chance of successfully tracking metal containers throughyour supply chain you should use the following guidelines:

1. Clearly define what you are trying to accomplish with an RFID solution. Consider theapplications that will consume the data generated and the business processes that willneed to adapt.

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2. Pick an RFID partner that has experience working in real world, high metalenvironments. Nothing beats experience when dealing with the complicated issuesaround tuning tags and readers for metal environments.

3. Pick the right frequency. Lower frequencies suffer less energy losses to eddy currents

and parasitic capacitance than do higher frequencies.

4. Design the right tag antenna including ferrite cored transponder coils. The highpermeability of the ferrite core allows a small transponder to be energized by theweaker field that exists close to the metal surface. The reduced size also means thatless energy is lost through parasitic capacitance.

5. Design tags to take advantage of the detuning that occurs on metal. For example,design tags that have a resonant frequency of 123kHz in air, so that they would have aworking frequency of 125kHz when attached to metal containers.

6. Design the tag antenna to insure the magnetic axis is parallel to the metal to ensurethe maximum coupling to the magnetic field parallel to the metal surface (see Figure 1above).

7. Choose the right reader antennae that are a compromise between a very sharp tune(maximum performance without detuning) and a very flat tune that is less affected bydetuning.

ConclusionDon't look at metal containers as a weight on your shoulders. Interference obstaclespresented by metal shouldn't stop you from adopting RFID tracking technology, whetheron your own or through a solution offered by mobile asset management providers. Thebeauty is that proper system design and engineering are really the only challenges, and

now finding the answer is easier with the introduction of mobile asset managementsolutions.

For more RFID related feature articles: www.usingrfid.com

Copyright 2005 TrenStar Inc.

About the author...

David Adams is Senior Vice President of Corporate Strategy & Technology for TrenStar Inc.Before joining TrenStar in 2002, he had emerged as an industry thought leader with 12

years of logistics operations experience and an additional 10 years of logistics technologydevelopment and supply chain and network optimization experience.

Adams is former vice president of operations at McKesson Primary Care, a Fortune 35company and division of McKesson Corporation, where he managed the day to dayoperations of a US$1 billion supply chain. He also helped to position supply chaintechnology companies Viewlocity and i2 Technology.

At the beginning of his career David held planning and operations positions at Pepsi Cola,Frito Lay and the US Navy. He received a B.A. in Economics from The Virginia MilitaryInstitute, a Masters of Business Administration from Troy State University, and a Mastersof Science in Operations Research from The Naval Postgraduate School.

TrenStar can be contacted through its web site, at http://www.trenstar.com

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