First antenna technology boosting UHF RFID-tag read performance

By Control Engineering Staff March 30, 2006

OMRON Corp. has developed a new electronic control antenna technology that it claims to be the first of its kind* that’s embedded in UHF-band RFID reader, improving RFID-tag reading performance—a patent is pending.

UHF offers significantly greater communications range than other frequency bands. Consequently, use of UHF RFID systems for full product traceability has seen tremendous growth in logistics industries, mainly in the United States, but also in other parts of the world. UHF tags, however, are subject to multipath interference**, an inherent problem of electromagnetic signals, which can make an RFID tag unreadable even if it is within the range of the reader.

So OMRON developed a new type of antenna technology that can electronically control the electromagnetic field emitted from the reader. By adopting this technology for UHF RFID systems, reflections are reduced, minimizing degradation of system performance due to multipath interference.

While a conventional antenna’s electromagnetic wave propagates over a wide area as it travels in a given direction, OMRON’s new antenna technology allows a wave with directivity to propagate in any specific direction, with the direction of the propagation controllable from the reader. This makes it possible to direct the wave’s direction of propagation, avoiding objects in the vicinity of the beam that may cause signal reflections. Reduced multipath interference results, leading to significantly improved tag read performance of UHF RFID readers.

End-user benefits include faster data transfer and more stable communications between the reader and RFID tag compared to conventional RFID systems. Moreover, it lessens the need for adjustment in varied system installation conditions and minimizes impediments to system performance.

OMRON plans to conduct experiments verifying and evaluating the validity of the technology for various potential applications, with the goal of commercializing and implementing the technology into RFID readers by the latter half of fiscal 2006.

Effects of electronic control antenna. With a conventional patch antenna, there are numerous holes in the electromagnetic field which can disable communications. OMRON’s new antenna technology is effective in eliminating these holes.

*Claimed to be the world’s first to be embedded in UHF RFID readers, according to a company survey as of March 2006.
**Multipath interference is caused by multiple waves taking different paths, creating spots in which waves attenuate each other within a communications area. When reading UHF RFID tags, multipath interference often occurs when a radio signal from the reader is reflected off of nearby objects, such as the floor and walls, resulting in multiple reflected waves in addition to the wave that directly arrives at the RFID tag.

Richard Phelps , senior editor, Control Engineering