Folded Antenna Coil for Eddy Current Mitigation
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Solution Overview
Problem
Conventional antenna devices face challenges in achieving satisfactory communication performance in limited mounting spaces due to eddy currents caused by metal components within electronic devices, which lead to weakened magnetic fields near the center of the device housing, and existing solutions either add thickness or require insufficient space between metal plates and housing.
Innovation Solution
An antenna device with a rectangularly wound coil and a magnetic sheet that overlaps with the coil, allowing the coil to be folded along the side or bottom of a metal plate, enhancing magnetic field distribution and communication efficiency in narrow spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antenna coil is mounted in the center region of the metal plate, then the communication performance is improved due to stronger magnetic field, but the mounting space is insufficient due to eddy current effects in the metal plate
Solution Approach 1:
The patent transitions from a two-dimensional planar mounting approach to a three-dimensional folded configuration. The antenna coil is folded along a fold line to create a spatial structure that extends in multiple dimensions, allowing the coil to achieve sufficient mounting area while avoiding the eddy current problem zone in the center of the metal plate.
Solution Approach 2:
The antenna coil is divided into multiple segments by the fold line, creating distinct folded portions that can be positioned in different spatial locations. This segmentation allows the coil to wrap around or adjacent to the metal plate, utilizing space that would otherwise be unavailable while maintaining the required coil area for communication.
2Area of stationary object
If the antenna coil is folded along the end of the metal plate, then the mounting space requirement is reduced, but the magnetic field distribution is weakened due to distance from the metal plate
Solution Approach 1:
The folded antenna coil is positioned to wrap around or nest adjacent to the metal plate structure. This nested configuration allows the coil to maintain close proximity to the metal plate surface, ensuring strong magnetic field coupling while utilizing the folded structure to fit within limited mounting space constraints.
Solution Approach 2:
The folding creates curved or rounded spatial paths for the antenna coil, allowing it to conform to the contours around the metal plate. This curved configuration optimizes the magnetic field distribution by maintaining consistent proximity to the metal plate surface while adapting to the available mounting space geometry.
3Device complexity
If a conventional planar antenna coil is used, then the structure is simple, but the communication performance is insufficient in limited mounting spaces due to eddy currents
Solution Approach 1:
The antenna coil transitions from a static planar configuration to a dynamic folded structure. The fold line introduces flexibility and spatial adaptability, allowing the coil to achieve optimal positioning relative to the metal plate while maintaining a relatively simple overall structure that can be manufactured and assembled efficiently.
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
Ensures satisfactory communication performance by widening the magnetic field distribution, allowing for effective mounting in limited spaces without compromising communication quality, thus improving design flexibility for electronic devices.
Implementation Method 1
such an antenna module communicates with an antenna coil of a transmitter such as a reader-writer by means of inductive coupling. That is, such an antenna module allows a magnetic field from the reader-writer to be received by the antenna coil to be converted into electric power
Implementation Method 2
a magnetic sheet formed of a magnetic substance and provided in such a manner as to overlap with a part of the antenna coil
Implementation Method 3
An antenna module incorporated in an electronic apparatus such as a mobile phone may cause magnetic flux from a reader-writer to be rebounded due to an eddy current produced by reception of the magnetic field from the reader-writer by a metal plate of a substrate, a battery pack, or the like inside the device
Data Source
AI summary
The purpose of the present invention is to provide an antenna device that makes it possible to ensure satisfactory communication performance even when the antenna device is mounted in an electronic apparatus with limited mounting space. An antenna device, incorporated in an electronic apparatus, which communicates with an external device via an electromagnetic field signal, comprising: a metal plate provided inside a housing of the electronic apparatus and facing the external device, and an antenna coil provided by winding a conducting wire in a approximately rectangular shape so that parts of the conducting wire that face each other in a width direction via an opening of the antenna coil come close to each other, and inductively coupled to the external device, wherein the antenna coil is provided along a side face of the metal plate.