Let the Competition Begin

By Mark Roberti

April 3, 2006—Last week, I wrote in this column that the issue of which frequency is best for tracking items was going to be the next great debate in the radio frequency identification community (see The Great RFID Debate: HF or UHF?). The debate is already in full swing and, as expected, it's very intense.

In an RFID Journal Webinar last week, sponsored by Impinj (a company that provides chip designs for silicon used in UHF RFID tags), Richard Ulrich, solutions architect for Wal-Mart Stores, made it very clear that Wal-Mart would like to see UHF used at the item level. He said using a single frequency to track pallets, cases and items lowers the total cost of ownership for the RFID system (see Wal-Mart Seeks UHF for Item-Level).


In the same Webinar, Chris Diorio, chairman, founder and vice president of RFID engineering at Seattle-based Impinj, laid out a compelling case for why UHF tags based on EPCglobal's second-generation Electronic Product Code standard could be used to track items. Diorio said that most of the common assumptions about UHF—that it doesn't work around water and metal, that tags can't be read when they are stacked one on top of another, and that tags are too big for many small items—are wrong.

HF and UHF tags use different methods of “coupling”—establishing a radio link for communicating—with the interrogator. HF tags operate in the near field, or from within one wavelength, while UHF tags use the far field. But Diorio explained that by changing the design of the UHF antenna, it can also communicate in the near field. In effect, it can operate like an HF tag and enjoy some of the same advantages HF has for item-level tagging. If you didn't have a chance to attend the Webinar, it’s worth viewing the archived version when it's posted on our Webinar site in a few days.

On the day of the Webinar, ODIN Technologies, a Dulles, Va., systems integration firm, announced the results of a battery of tests the company conducted using three commercially available UHF EPC Gen 2 tags and four commercially available HF tags compliant with the ISO 15693 standard. ODIN ran the tags through five performance tests and against three pharmaceutical use cases, for a total of eight test categories. Its "Battle of the Frequencies" report said HF tags beat UHF tags by a “technical knockout.” HF tags performed best in five of the categories, while UHF tags won in two. In one category, the two frequencies performed equally well (see Study Says HF Rules for Pharma Items).