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SmartX Launches Multilinear RFID Portals

The technology, which gathers multiple antennas in different positions, allows readings where the exact positions of tags cannot be guaranteed, and at a lower cost.
By Edson Perin

Circularly polarized antennas allow RFID tag readings at shorter distances and wider reading angles. For the reading to take place efficiently, the tag can be positioned vertically or horizontally, always in relation to the same antenna positioning.

However, Moreira explains, tags positioned perpendicular to the antenna plane (horizontal for top antennas or vertical for side antennas) may have their readings impaired. One commonly used technique for reading tags perpendicular to the plane of a portal's side antennas is the adoption of antennas on the top, leaving the antennas positioned on the sides to ensure the coverage of tags positioned vertically and horizontally.

Havan's Alexsandro Eloi Venancio
However, RFID tags positioned perpendicular to the plane of the side antennas and at the bottom of a goods pallet can still have their readings impaired. "With that, more antennas should be placed," Moreira explains, "which makes it common to find portals with up to eight antennas to ensure 100 percent readability. This will still depend on the type of tag," resulting in higher deployment costs.

Examples of applications using circular-polarization antennas include airport baggage-scanning solutions. "You never know the position of the RFID tag that should be read," Moreira says. "Whether vertically or horizontally, the tag is likely to be read by one of the numerous strategically placed circularly polarized antennas."

SmartX's Pedro Moreira
Multilinear-polarization antennas enable RFID tag readings at shorter distances due to the small size of their multiple integrated antennas. That is, they have less gain over circular and linear antennas, but allow more efficient readings of a larger number of tags in a smaller space, thereby avoiding unwanted readings in the vicinity of the portals.

With the adoption of RF signal-confinement techniques, it becomes possible to limit the read zone and adopt higher signal strength in RFID interrogators without reading tags in neighboring read zones. Attempts to deploy this technology in the past have not been successful in Brazil, however.

"With the expertise and practical experience of SmartX's technicians, we took the challenge," Moreira states. "Now, the portals are offering results. Therefore, the adoption of multilinear antennas is not new in Brazil. The novelty is the implementation and proper manufacture of the portals."

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