Five RFID Myths Exposed - Page 2
January 06, 2004
A global UHF tag could reduce tag manufacturing costs. In general, the UHF frequency varies by continent (although more granular differences exist). The Americas use 915 MHz, Asia uses 950 MHz, and Europe uses 869 MHz. Companies like Intermec and its peers will have to develop frequency agile interrogators and tags to realize this dream, but it promises products that can be used globally, and that can be shipped from one continent to another.
Within a warehouse, tags could improve logistics, helping the industry use oldest components first. A tag would say, "I'm right here. I am #35 of the December 2003 batch of steering wheels."
Just in Time logistics (JIT) is a manufacturing process imported to the U.S. and Europe from Japan several decades ago. The essential idea is that if components are used when delivered, and delivered immediately before they are needed, both manufacturers and their suppliers can realize substantial cost savings by reducing lost and destroyed inventory and also by reducing warehousing costs. RFID technology should eliminate the out of stock problems that JIT can create.
The eventual aim of RFID in retail and manufacturing is an aim once touted for the Internet itselfeliminate the intermediary. A perfect supply chain would require no distribution center. Products would be delivered directly from the factory to the retail center.
The two dimensional bar code label can realize some of these goals. It can enable unattended fixed reading or attended wireless reading, providing many of the warehousing and manufacturing improvements described above. In many implementations, it also complements the RFID tag, providing backup information if the RFID tag is damaged.
Myth 2: The simple RFID application
As mentioned in the previous article, RFID works in the RF environment, which is effected by moisture, weather, radiation, invisible RF interference, and even by the material of the building in which it is used and the materials stored in that building. It also varies depending on the material to which the tag will be affixed.
The read/write range is not adjustable but may vary with environmental conditions (and will certainly vary if RF interference varies).
The invisibility of RF, as those who deploy it in WLANs know, makes it difficult to find the source of problems, even with sophisticated RF mapping tools. The issue of polarization further complicates troubleshooting.
The RFID command language is not intuitive and anyone creating an application for it needs to learn to use it and should also have previous RFID deployment experience. The language can change over time, requiring continuing education.
One example of the complexity of RFID is the case where you pull the trigger of a handheld interrogator and read the tag behind you. Experienced WLAN managers know that the propagation path of an antenna's signal is not intuitive. Many antennas propagate to some extent behind them as well as in front of them. In the case of handheld RFID readers, users have to be told to hold the reader in front of their body because humans, filled with water, are perfect RF barriers. This will prevent the reader from reading a tag behind them.
Of course, the above example doesn't take into account other common RF issues such as reflection, diffraction, attenuation, and interference. The reflection of a circular polarized signal is particularly complex, too complex in itself to describe in this article.
In short, each individual RFID application requires unique programming and customized database software. Each class of items to be tagged requires a unique tag designed for that item's material composition and usage environment. There is therefore no universal tag. Instead, tags are application specific.
Of course, some applications, like car tires and cardboard boxes, could consume hundreds of millions or even tens of billions of the same tag. These applications could command and create the equivalent of a universal tag.