Metal-Mount RFID Antenna Layout for UHF Interrogation Distance
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Solution Overview
Problem
RFID devices operating in the ultra-high frequency range are rendered inoperative in metal environments due to electromagnetic scattering, coupling, and interference, leading to ineffective interrogation and complex manufacturing processes.
Innovation Solution
The RFID device features an asymmetrically arranged first and second metal layer on a substrate with electrically insulated extension parts, allowing adherence to metal surfaces while maintaining electrical insulation, thereby simplifying manufacturing and enhancing interrogation distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UHF antenna structures are used on metal surfaces, then manufacturing is simplified, but electromagnetic scattering and coupling cause the RFID device to become inoperative
Solution Approach 1:
A non-metal substrate is introduced as an intermediary between the RFID device and the metal surface. This substrate prevents direct contact between the antenna and metal, thereby eliminating electromagnetic scattering and coupling issues while maintaining manufacturing simplicity through direct attachment to the metal surface.
2Length of stationary object
If metal layers are folded to cover multiple surfaces of the substrate, then interrogating distance is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of folding metal layers to extend in three dimensions, the patent extends the metal layers in a single plane beyond the substrate boundaries. This planar extension achieves the same effect of increasing antenna effective area and interrogating distance while maintaining simple flat manufacturing processes without folding or multi-surface assembly.
3Length of stationary object
If metal layers are extended beyond substrate boundaries, then interrogating distance is increased, but electrical insulation between layers becomes more difficult
Solution Approach 1:
The non-metal substrate serves as a continuous electrical insulator that extends beneath the protruding metal layers. This substrate intermediary automatically provides electrical insulation between the first and second metal layers without requiring additional insulation layers or precise alignment, simplifying manufacturing while maintaining extended interrogating distance.
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
The solution enables effective RFID operation on metal surfaces with increased interrogation distance and simplified manufacturing, overcoming the limitations of conventional designs.
Implementation Method 1
enable the first metal layer and the second metal layer to be adhered to each other with electrical insulation effect
Implementation Method 2
a reflection phenomenon from the surface of the good conductor will be generated because there has no electromagnetic wave inside the good conductor
Implementation Method 3
it will also cause destructive interference due to the phase variation between the incident electromagnetic wave and reflected electromagnetic wave
Implementation Method 4
when a dipole antenna is arranged onto the top of the metal object, e.g. on the top surface of the metal object, a reverse current is induced on the bottom surface opposite the top surface, whereby electromagnetic wave is eliminated
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3~4A
AI summary
The present invention provides a RFID device arranged on an object surface, comprising a substrate, a first metal layer and a second metal layer. The first metal layer has a first connecting surface having a first adhering layer for adhering to the first surface of the substrate, wherein a RFID element is electrically connected to the first metal layer and a length of the first metal layer is larger than a length of the substrate such that the first metal layer has a first extending part extending outwardly from the lateral surface of the substrate. The second metal layer has a second connecting surface having a second adhering layer formed thereon for adhering the second metal layer on the second surface, wherein the first extending metal layer is attached onto but electrically insulated from the object surface or the second metal layer.