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Tag Placement

As a result of our research in tag performance and the effects of products and environment we have developed a complete testing system. Tag-reader-product (TRP) testing accounts for the three major factors in the performance of and RFID system. We have found that simply testing tags in isolation is not enough to understand how they will perform, it is important to examine the interaction of tag and product to properly model how a tagged product will behave in various scenarios. The TRP testing system which has been developed allows a product to be completely mapped, and its surfaces rated for their suitability for RFID tags. The system provides three important pieces of information about products:

• Best tag placement: Plots are produced of exactly how a product appears to an RFID reader, clearly showing not only the best places to install a tag, but also the effects the placement will have on the tag's range. The tests are performed with actual tags, to guarantee that they are accurate.
• Imperfect tag positions: Another important factor in tag position is position error: when a tag is accidentally installed some distance away from its optimum position. Our testing can determine the allowable margin of error to achieve the performance required. For example a difference in tag position of only 1cm can sometimes halve the range at which a product can be read by a reader.
• Angled or moving reads: Most of the time products are not read head-on and stationary. They might be moving along a conveyor, or turned sideways on a pallet. Products in these situations do not behave as they do when they're directly in front of a reader. The testing system can model these situations as well, so that the final product analysis will cover a product through the entire supply chain, not simply when it's sitting stationary in front of a reader.

This plot is of a case of bottled water. Tags installed in the dark areas see very poor or no response. The yellow areas see the best response, and the difference can mean a four-fold increase in read range.

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For further details about this project, please write to Hugo Mallinson at hfm21[at]cam.ac.uk