Jul 09, 2008This article was originally published by RFID Update.
July 9, 2008—Metal is not the same strong shield it used to be for blocking UHF RFID reads, according to new benchmark test results released today by ODIN technologies. "There is a well circulated myth that passive RFID does not work on metal. There are other myths that only one or two tags will actually work reliably on metal objects. Both myths are conclusively 'busted' by the Metal Mount RFID Tag Benchmark," ODIN said in its press release.
ODIN issued the report after testing 17 varieties of UHF tags designed specifically for use on metal objects. The testing found that RFID can be used reliably in high-metal environments, but using metal-mount tags does not guarantee success.
"We found substantial differences in performance among the tags tested," Bret Kinsella of ODIN told RFID Update. "Sometimes when engineers optimize a tag for a particular use case, they make it inherently harder to perform in other settings."
Some metal-mount tags actually performed worse than general-purpose RFID tags that ODIN evaluated in previous benchmark tests. ODIN has published 10 previous benchmark studies on tag and reader performance, but this is the first time it has released a report on specialty tags, according to Kinsella. The better metal-mount tags significantly outperform general-purpose tags on metal, and ODIN will recommend their use to clients, Kinsella said.
"We've seen significant improvement in metal-mount tag performance over the last couple of years," Kinsella said. "Even a year ago, there were very few metal-mount tags that were versatile and could provide reliable performance. There are more now, but I should note that some tags that have been available for awhile have not improved."
While the metal-mount testing found major performance differences among different tags, performance did not vary significantly based on the type of metal present, Kinsella said. ODIN's test environments were designed to simulate common RFID use cases, such as identifying servers in a data center and tracking parts and tools in an industrial setting. To make the results more applicable to real-world conditions, ODIN tested for material dependency and metal proximity, which were not evaluated in previous benchmark tests. The new tests were designed to predict performance when tags were placed next to other metal surfaces and used around other metals and tagged items. Tags were also tested for the amount of power they needed to communicate, sensitivity to reader orientation, and range.
"A lot of tags that are very good at identifying a single unit are very poor as soon as you introduce another metal object, such as when the item is put onto a metal table, or put into a rack with other servers," said Kinsella. "A lot of people may not be aware that these situations are causing their reading problems."
ODIN has a video clip on its website that provides more details about the testing.
The 17 tag types tested came from six vendors: Avery Dennison; Confidex; Emerson & Cuming; Intermec; Omni-ID; Sontec; and TROI.
Avery Dennison was the only vendor whose products were also evaluated in testing released by the European EPC Competence Centre (EECC) in June. The EECC tests were not specific to metal-mount tags but evaluated performance of 20 UHF tag inlays on a variety of materials (see Report Reveals RFID Performance on Different Surfaces).
ODIN is headquartered in Dulles, Virginia, and provides RFID testing, development, and integration services. In addition to the metal-mount tag report, ODIN also offers benchmark studies on Gen2 tags, RFID readers, medical cabinets and other topics, all of which can be purchased from its website.
