Planar NFC Antenna with Magnetic Sheet for Metallic Cover Integration
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Solution Overview
Problem
In miniaturized and multi-functional electronic devices, the structural restrictions and electromagnetic wave absorption by metallic covers hinder the achievement of high communication performance for Near Field Communication (NFC) antenna modules, necessitating a solution that enhances design freedom and communication efficiency without compromising the strength of the device.
Innovation Solution
The proposed antenna device incorporates an antenna coil wound in a planar shape with a magnetic sheet inserted into the coil opening, overlapping with the metallic cover between the opening and its end, allowing magnetic flux to form a magnetic field loop, thereby improving communication performance while minimizing structural restrictions and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opening is provided at the metallic cover to improve communication performance, then electromagnetic wave absorption is reduced, but the strength and structural integrity of the metallic cover deteriorates
Solution Approach 1:
A magnetic sheet is introduced as an intermediary component between the antenna coil and the metallic cover. The magnetic sheet guides magnetic flux from the antenna coil through the metallic cover without requiring openings, thereby maintaining communication performance while preserving the structural integrity of the metallic cover.
Solution Approach 2:
The magnetic flux guidance function is extracted from the metallic cover structure itself and assigned to a separate magnetic sheet component. This allows the metallic cover to maintain its closed structure for strength while the magnetic sheet handles the electromagnetic flux routing.
2Reliability
If multiple openings are provided at the metallic cover to enhance communication performance, then electromagnetic wave absorption is reduced, but the device complexity and structural restriction increase
Solution Approach 1:
The magnetic sheet serves as a mediator that enables effective magnetic flux guidance through the metallic cover with minimal openings. This intermediary component simplifies the overall structure by consolidating the electromagnetic function in a dedicated element rather than requiring multiple structural modifications to the cover.
Solution Approach 2:
The position and size parameters of the opening in the metallic cover are optimized to work effectively with the magnetic sheet. By carefully controlling these parameters, high communication performance is achieved with a single minimal opening rather than multiple larger openings.
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
This configuration enhances communication performance by directing magnetic flux effectively through the antenna coil, reducing the need for additional openings in the metallic cover, thus maintaining device strength and design flexibility.
Implementation Method 1
an antenna coil inductively coupled to the external device... magnetic flux from the external device enters into the opening provided at the metallic cover, and passes through the coil opening of the antenna coil along the magnetic sheet
Implementation Method 2
passes through the coil opening of the antenna coil along the magnetic sheet to outside from the end of the metallic cover to form magnetic field loop
Implementation Method 3
metallic cover formed with an opening near an end of the metallic cover and arranged at surface side of the antenna coil opposing to the external device
Data Source
AI summary
An antenna device incorporated in an electronic apparatus and communicating with an external device via an electromagnetic field signal, including: an antenna coil inductively coupled to the external device and provided by winding around a conducting wire in planar shape; a magnetic sheet arranged to overlap with the antenna coil mutually along the antenna coil by inserting the magnetic sheet into a coil opening provided at center side of the antenna coil; and a metallic cover formed with an opening near an end of the metallic cover and arranged at surface side of the antenna coil opposing to the external device, wherein the antenna coil is arranged to overlap with the metallic cover in a region between the opening and the end of the metallic cover at a backside surface of the metallic cover opposite to a surface of the metallic cover opposing to the external device.