Once a tag chip is designed, how can I test its operation?
—Name withheld
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There are two essential elements to passive RFID transponders: the chip and the antenna. The chip is tested in the same way that all microchips are tested—there is special hardware that confirms whether gates and other components are operational. Typically, when an antenna is attached, a reader attempts to communicate with the tag. Sometimes, it writes a serial number to that tag, assuming the tags are preprogrammed. If the tag can successfully communicate with it, then it is properly functioning.
However, I suspect that you may be referring not to testing whether the tag operates, but rather how well it performs. Typically, companies design a new tag antenna and then place the tag within an anechoic chamber, which is intended to block out electromagnetic energy from exterior sources and absorb energy within the chamber, in order to prevent reflected energy from reaching the tag. A reader antenna or antenna is placed within the chamber to measure the strength of the signal from the tag; a stronger signal correlates to longer read distance and better performance. The tag is usually rotated in 5-degree increments, enabling testers to ascertain the tag’s performance in various orientations to the reader antenna.
By comparing the results of these measurements within the anechoic chamber, you can determine a new tag design’s expected performance. Some tags, of course, are built to work on objects containing water, or on a specific material, such as glass. Obviously, in such a case, you would need to test the tag design on a piece of glass to determine its performance characteristics.
Voyantic offers a product called Tagformance, which helps companies assess new tag designs (see Voyantic Helps Companies Put RFID Tags to the Test).
—Mark Roberti, Founder and Editor, RFID Journal
