About my blog...
RFID: Just another 4-letter word.  From this title alone, you probably think you know what my feelings are concerning RFID.  Actually, you would be wrong.

My name is Karen Radde and I have been living and breathing RFID since 2004.  My division of BlueBean, RFIDSupplyChain.com, takes calls from all types of people and companies thinking about implementing RFID.  We provide help for those who are looking to purchase a RFID reader for internal testing or RFID equipment for project implementation.

This blog title reflects the feelings we hear from the other end of the call.  We can't tell you exactly how far you will be able to read in your environment.  We can't tell you exactly what hardware will perform the best in your environment.  There are so many variables that affect the performance of RFID that it is as much of an art as a science.  What we can do is provide you with guidelines and recommendations based on our extensive knowledge (or recommend an excellent RFID consulting company), the ability to purchase RFID hardware and RFID solutions at great prices and the knowledge to support you and your products after the purchase.

After all, our goal is to turn your view of RFID from a 4-letter word to a technology that allows you to seamlessly improve your business.
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How Metals and Liquids Affect Read Range
Posted Thursday, April 3, 2008 by Karen Radde
In general, liquids tend to absorb UHF RF energy while metals tend to reflect it. 

Liquids:  As stated above, liquids absorb UHF RF energy.  What is important to note is that the liquid does not have to actually be in liquid form.  If the item has the ability to hold or attract moisture, you will have to take that into consideration.  For example, a large paper manufacturer found out that because paper has a high moisture content, their large rolls of paper proved more challenging than expected.

Metals:  In most cases, metals reflect UHF RF energy.  This can be a positive or a negative.  In some cases, the metal may reflect the signal in random and unwanted directions. If done correctly, it can help reflect the signal back to the antenna thereby improving performance.  There are many items that have metal content that are not easily apparent.  For example, the shiny packaging you see on grocery items is metallic. 

Therefore, it is important to test your RFID solution thoroughly in your environment with your items as liquids (or high moisture content) and metals (or mineral compounds) will definitely affect the UHF RF energy.  Neither of these should stop you from implementing RFID technology.  With proper system design and engineering, the issues can be addressed and overcome.
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How Tag Placement Affects Read Range
Posted Wednesday, March 19, 2008 by Karen Radde
In the early days of RFID, RFID tags were placed haphazardly on the cases and packages with no thought on how it would affect the read range.  Now we know better!

We now know that there are locations on every package that are hostile to RF and others that are friendly.  This is important to not only the individual package, but also when the packages are stacked or in a line.  Why does this happen?  Packaging material and item materials play a major role.  For example, if you have a case of liquid laundry detergent, the tag will perform better when away from the liquid.  There is software that shows you the RF-friendly locations (in green) and the RF-hostile locations (in red).

Software displaying tag placement analysis

This is a small but critical step in any RFID solution.  After all the time, money and resources utilized in the design and implementation of an RFID solution, wouldn't it be a shame if the warehouse personnel placed the tag right in that big red spot?

Next time I will discuss the challenges of metals and liquids.
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How Tags Affect the Read Range
Posted Tuesday, February 19, 2008 by Karen Radde
With RFID UHF tags, there is a general rule of the thumb:  The larger the tag, the longer the read range.  This is generally true when comparing tags from the same time period.  As with any technology, performance improves while the size decreases over time.  Therefore, a 4' x 4" tag from 2005 will generally not perform as well as a 2" x 2" tag from 2008.

A critical component is the antenna design.  Unfortunately, there is no one best antenna design.  The optimal design is dependent on the application which includes form factor, size limitations, dielectric characteristics of the material to which it is being attached, frequency optimization, etc.
Various RFID tag antenna types

Another general rule of thumb is that a single dipole tag properly lined up with a linear antenna will have a longer read range than a dual dipole tag with a circular antenna.  In my earlier post about RFID antennas, I discussed the difference betwen linear and circular antennas.

Although this is a high-level view, the basic RFID tag factors which affect read range are:
     1.  size
     2.  antenna design
     3.  type

The next in this series will discuss how the item itself affects the read range.
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How RFID Readers and Antennas Affect the Read Range
Posted Tuesday, February 12, 2008 by Karen Radde

As I mentioned in my previous blog about the million dollar question, "How far will it read?", two of the factors are the reader and antennas (and remember we are discussing passive RFID).

Passive UHF RFID readers can affect the read range depending on the manufacturer and the power level.  In the US, FCC regulations cap the output power at 4 watts, whereas in Europe it is only 1 watt.  There are studies available for purchase that detail the testing results of readers and antennas in a controlled, RF-friendly environment.  These are appropriate for general guidelines, but each environment is different and a reader that did not test at #1 in the study may be the better one in your environment.

Passive UHF RFID antennas can also affect the read range depending on the manufacturer, the type of polarization and the gain.  Antennas can be either linearly polarized or circularly polarized.  When the direction of the electric field is in one plane, it is called "linear polarization".  When the direction of the electric field is rotated around the axis of propagation, it is called "circular polarization".  Linear polarized antennas will provide a longer read range as compared to circular.  Also, an improvement in antenna gain is achieved by focusing the radiated RF into narrower patterns for the purpose of increasing the power in a specific direction.  In general, the higher the gain the longer the read range. 
Polarization of a Linear AntennaPolarization of a Circular Antenna




My next post will cover how RFID tags affect the read range.

 

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What's Frequency Got to Do With It?
Posted Monday, February 11, 2008 by Karen Radde

Contrary to Tina Turner, frequency like love has everything to do with it.  RFID technologies operate at many frequencies, but I will only cover the most common passive ones here:  low-frequency (125 MHz), high-frequency (13.56 MHz) and ultra high-frequency (860-960 MHz).

Low-frequency (LF) passive solutions operate around 125 MHz, use less power and are less susceptible to liquids.  Read ranges are in inches.

High-frequency (HF) passive RFID solutions operate around 13.56 MHz, use more power and are less susceptible to metals.  Read ranges are at most a few feet.

Ultra-high-frequency (UHF) passive RFID solutions operate between 860-960 MHz (depending on the country), uses the most power of the three and are less likely to pass through materials.  The data transfer rate is faster than LF and HF and the read ranges can be as high as 30 feet or more.

As you can see, frequency plays a role in determining the read range of a solution.  Next time I will continue with the role the reader and antennas play.

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Super Bowl - What a plan!
Posted Tuesday, February 5, 2008 by Karen Radde
I don't know about you, but this Super Bowl had to be one of the most Steve Spagnuolo, Defensive Coordinator for the 2008 Champions New York Giantsexciting games I've ever seen.  If I had a vote on the MVP, it would have to go to Steve Spagnuolo, Defensive Coordinator of the New York Giants.  Although there were many players that played exceptionally well, it was the defensive plan of Spagnuolo that won the game. 

So what does this have to do with RFID?  Bear with me while I try to explain.  Any implementation is as only as good as the plan - whether we are talking football or RFID projects. 

Many clients call because they have an issue that they feel RFID can help.  Some clients try to do the design of the RFID project themselves - or they hire a company that offers RFID consulting as one of many services in their portfolio.  I've heard many people say that they are technical so they should not have a problem.  Would someone be able to do your job properly if he only did it once with no experience?  As you can imagine, the resulting "plan" is not solid and problems multiply as time goes by.

For this reason (and others), it is valuable to hire a RFID consulting and systems integration companythat focuses only on RFID technology for at least the design phase.  That way you are guaranteed a plan that will best meet your needs and allows you to triumph over your competition!

As a Vikings fan, I patiently await for next season...
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The Million Dollar Question: How far will it read?
Posted Monday, January 28, 2008 by Karen Radde
Invariably, every discussion about an RFID solution comes down to the same question:  How far will I be able to read the tag?  And, of course, everyone expects a quick and reliable answer.  For those of us that deal with RFID every day, we know that this seemingly innocuous question is anything but. 
RFID waves with RFID tags
For passive RFID (where the tag does NOT have its own power source), there are many variables that affect the read distance including:
    • the frequency of the RFID hardware 
    • type of antenna 
    • placement of antenna 
    • type of tag 
    • placement of tag 
    • item being tagged 
    • what the item is made of 
    • what the items contains 
    • the packaging around the item 
    • presence of metal 
    • presence of liquids 
    • temperature 
    • humidity 
    • other RF interference 

You get the picture.  It is easy to now see why there is no exact answer to this question without testing in your envirornment.  In following posts, I will discuss some of these points in additional detail.

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