Metal Chip Card Antenna Layout for RF Shielding Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Metal smart cards face interference with RF signals due to electromagnetic shielding, leading to poor communication performance and limited interoperability with NFC readers, and existing solutions complicate manufacturing or compromise mechanical integrity.
Innovation Solution
A smart card design with a metal layer featuring a recessed cavity and a non-conductive antenna configuration, where the antenna's turns are routed to flow in the same direction, minimizing energy losses and phase distortions, and utilizing a dielectric material in the cavity to enhance signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a metal layer is used in the smart card body for aesthetic appearance and quality impression, then the card provides high-end aesthetics and significant weight, but the metal acts as electromagnetic shielding and blocks or interferes with RF signals exchanged by the RF antenna
Solution Approach 1:
The patent divides the antenna structure into multiple segments: a first set of turns routed along the periphery of the card and a second set of turns routed outside the cavity, connected by at least one turn extending toward the inside of the card. This segmentation allows the antenna to navigate around the metal layer and cavity while maintaining signal integrity and avoiding electromagnetic shielding interference.
Solution Approach 2:
The patent utilizes three-dimensional routing of the antenna turns, with portions extending both outside and inside the cavity region. This dimensional approach allows the antenna to access magnetic field lines from multiple spatial perspectives, effectively compensating for the blocking effect of the metal layer and improving RF signal transmission through the card.
2Reliability
If a ferrite layer is placed between the antenna and metal foil to reduce interference, then RF signal interference is reduced, but card manufacturing becomes complex and the card can only communicate from one side
Solution Approach 1:
The patent removes the ferrite layer from the card structure entirely, replacing it with a carefully designed antenna routing configuration. By extracting this additional component and relying on the intrinsic properties of the metal layer and antenna geometry, the solution simplifies manufacturing while maintaining bidirectional communication capability.
Solution Approach 2:
The patent allows the metal layer itself to serve the dual purpose of providing aesthetic appearance and structural integrity, while the antenna routing is designed to work harmoniously with the metal layer's electromagnetic properties. The system uses its own components (metal layer and antenna turns) to achieve signal transmission without requiring additional shielding materials like ferrite.
3Reliability
If a cavity is created in the metal layer to accommodate the antenna, then RF signal transmission is improved, but the mechanical integrity of the card is compromised and the cavity area reduces the antenna insertion space
Solution Approach 1:
The patent creates a localized cavity only in the specific region where the RF chip and antenna turns require insertion, while maintaining the metal layer's integrity in other areas. This localized approach minimizes the impact on overall mechanical strength while providing sufficient space for the antenna configuration and chip mounting.
Solution Approach 2:
The patent nests the RF chip and antenna turns within the cavity structure, which itself is integrated into the metal layer. This nested configuration allows the antenna and chip to be housed within the card body without requiring external protrusions or significant structural modifications, preserving both mechanical integrity and RF performance.
4Loss of energy
If the antenna turns are routed to flow in the same direction in both sets, then energy losses and phase distortions are minimized, but the antenna routing becomes more complex
Solution Approach 1:
The patent employs asymmetric routing where the first set of turns is positioned along the periphery and the second set is positioned outside the cavity, connected by turns extending inward. This asymmetric configuration naturally guides the current flow in a consistent direction through strategic placement rather than requiring complex additional routing elements, reducing energy loss while maintaining manufacturability.
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 design achieves stronger signal intensity, reduces communication errors, and simplifies manufacturing, while meeting or exceeding ISO standards for load modulation and activation thresholds.
Implementation Method 1
at least one RF antenna electrically connected to the RF chip by a conductive physical connection, the antenna being disposed on a non-conductive layer deposited on the metal layer, the RF chip being disposed at the metal layer and comprising a first set of turns routed along the periphery of the card
Implementation Method 2
utilizing a dielectric material in the cavity to enhance signal strength
Implementation Method 3
The metal acts as electromagnetic shielding and blocks or interferes with the RF signals exchanged by the RF antenna with the outside world
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The present invention relates to a smart card (CD1) comprising: - a metal layer (103) comprising a cavity and a junction (104) connecting the cavity to an edge of the card; - an RF chip (110); - an RF antenna (AT1) electrically connected to the RF chip by a conductive physical connection, the antenna being arranged on a non-conductive layer deposited on the metal layer, the RF chip being arranged at the metal layer and comprising - a first set of turns (SET1) routed along the periphery of the card, comprising at least one turn extending towards the inside of the card, and electrically connected to - a second set of turns (SET2) routed outside said cavity, along the edges of said cavity, - the turns of the two sets of turns being arranged so that the current flows in the same direction in both sets of turns.