Flexible On-Metal RFID Tag Structure Without Ferrite Layers
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Solution Overview
Problem
Conventional radio frequency tags, particularly NFC or HF tags, face significant challenges when placed on metallic surfaces, as their read range is drastically reduced due to interaction with metal, making tracking of metal assets difficult, and they require costly ferrite layers or thick spacers, which are not suitable for labels or curved surfaces.
Innovation Solution
The development of NFC or HF tags and dual NFC/HF and UHF tags with a flexible design that includes a nonconductive face stock, an antenna inlay, a flexible spacer layer, and a ground plane layer, eliminating the need for ferrite materials and allowing functionality on both metallic and non-metallic surfaces, suitable for printing and encoding with conventional RFID printers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RF tags are placed on metallic surfaces, then the tags can identify metal assets, but the read range is drastically reduced and the tag cannot be read or interrogated by a reader
Solution Approach 1:
The patent introduces a nonconductive spacer layer as an intermediary between the antenna and the metallic surface. This spacer layer prevents direct interaction between the conductive antenna and the metal surface, thereby maintaining the antenna's resonant properties and read range while still enabling the tag to be attached to and identify metal assets.
2Adaptability or versatility
If ferrite layers are added to improve on-metal performance, then the tag can operate on metal surfaces, but the cost increases significantly
Solution Approach 1:
The patent replaces expensive ferrite materials with a inexpensive nonconductive spacer layer made from common materials. This substitution maintains the on-metal operation capability while dramatically reducing the manufacturing cost, making the tags economically viable for widespread deployment.
3Reliability
If thick spacers are used to prevent metal interaction, then the tag can read on metal surfaces, but the tags are not suitable for labels or curved surfaces
Solution Approach 1:
The patent employs a thin, flexible nonconductive spacer layer instead of thick rigid spacers. This thin film approach maintains sufficient electrical isolation to prevent metal interaction while being thin and flexible enough to conform to curved surfaces and fit within label thickness constraints, thereby achieving both reliable metal surface operation and adaptability to various form factors.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These tags effectively operate on both metallic and non-metallic surfaces without ferrite, are cost-effective, and suitable for labels and curved surfaces, maintaining functionality across various applications.
Implementation Method 1
near-field communication (NFC) or high frequency (HF) radio frequency tags
Implementation Method 2
Electronic devices that can transmit a modulated EM signal that can be detected by an appropriate reader
Implementation Method 3
a spacer layer of a flexible nonconductive or dielectric material or combination of such materials
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c
AI summary
A radio frequency identification (RFID) tag including a face stock layer, an antenna inlay beneath the face stock layer and comprising a radio frequency (RF) antenna and an integrated circuit (IC) chip, a spacer layer beneath the antenna inlay, and a metal ground plane. The antenna inlay may include a near-field communication (NFC) or high frequency (HF) antenna, and optionally may include an ultra-high frequency (UHF) antenna. The spacer may be made of a flexible polypropylene, and the metal ground plane may be made of aluminum.