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Researchers Seek Challenging Sites for Multibeam Antenna Pilot

The Fraunhofer Institute for Integrated Circuits has developed an antenna with four elements and nine different beams fed to those elements that can detect the precise location and direction of tags in challenging environments.
By Claire Swedberg
Aug 09, 2017

The Fraunhofer Institute for Integrated Circuits IIS, a German research institution, is seeking companies to pilot its new Multibeam Antenna, which is designed to track the directions of tags as they pass an ultrahigh-frequency (UHF) RFID reader, and to capture tag reads more reliability than traditional antenna deployments in a crowded or environmentally unfriendly location. The antenna can be used with all standard UHF readers. It includes a remote-control interface or it allows for applications to be implemented on a user's reader platform.

Fraunhofer IIS, located in Erhlangen, is an application-oriented research institution for microelectronic and IT solutions. It conducts research into audio media technologies, communications systems, X-ray technology, positioning systems, smart sensing technologies and supply chain services. The company says it designed the Multibeam Antenna as a replacement or alternative to existing UHF RFID installations in which multiple antennas are installed around a reader, often in a wide array to ensure accurate reads.

Fraunhofer IIS's Multibeam Antenna
Some environments are more challenging for RFID technology than others. In spaces such as warehouses, busy retail locations or manufacturing facilities, for instance, ensuring that tags are read reliably can require a complex arrangement of readers and antennas. If a portal, or a series of portals, is installed at a warehouse dock door, for example, tags may pass quickly in large numbers and in multiple directions, and capturing each tag ID and identifying its location can thus be difficult.

Traditional installations consist of a reader with several antennas to detect a tag's precise location and the direction in which it is moving. Common readers provide up to eight RF ports, each connecting an antenna with a fixed beam. A typical gate can be equipped with eight antennas, with four antennas installed at each side. To distinguish the direction in which tags are moving, the antennas needs to be mounted at some distance from to each other—typically several meters, says Mario Schühler, Fraunhofer IIS's antennas group manager.

"Direction identification, in general, is not possible with antennas of fixed beams and common readers," Schühler explains. For that reason, he adds, "moving direction can be roughly estimated [only] with complex installations."

In other cases, readers operate with fewer antennas, but the results may be a reduction in read performance, especially if the environment in which tags are being interrogated is hostile. For instance, if tags were moving quickly past a reader (on a forklift, for example), the antenna would have a limited opportunity to capture each tag's ID number. If the environment included hundreds of tags, Schühler says, and if the tags were attached near metal or containerized liquid, the effort would become that much harder.

Fraunhofer IIS began working on a solution to this problem in 2016. The result, the company reports, is an antenna that offers up to nine individual beams, fed to four individual antenna elements (transducers) by a feed network. This network provides the nine predefined signal constellations, which cause nine separate illuminations of the antenna elements. The illuminations differ in their phase distributions among the elements, making it a form of phased array with discrete illumination patterns.

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