Antenna Shield Part Reduces SAR Without Increasing Device Size
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Solution Overview
Problem
Existing wireless communication devices face challenges in reducing the Specific Absorption Ratio (SAR) while maintaining efficient radiation characteristics, which is essential to prevent health risks and miniaturize electronic devices.
Innovation Solution
The design incorporates an inverted F antenna with a substrate and printed wiring board structure, featuring a second ground conductor with a shield part that partially overlaps with the antenna element, allowing for reduced SAR values without compromising radiation efficiency, and enabling a reduction in device size and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the antenna is placed away from the human body to reduce SAR, then the SAR value decreases, but the device size and thickness increase
Solution Approach 1:
A ground plane structure is introduced as an intermediary element between the antenna and the human body. The ground plane includes a first ground conductor on the antenna side and a second ground conductor on the opposite side, creating a shielding effect that reduces SAR without requiring increased distance from the body
Solution Approach 2:
The solution transitions from a one-dimensional distance-based SAR reduction approach to a multi-dimensional approach by utilizing the ground plane structure with conductors distributed across different spatial layers and positions, achieving SAR reduction through spatial configuration rather than simple distance increase
2Object-affected harmful factors
If a symmetrically structured ground plane is used to shield electromagnetic waves, then SAR is improved, but device complexity increases
Solution Approach 1:
The ground plane structure employs local quality variation where the first and second ground conductors are positioned asymmetrically relative to the antenna element, with specific overlap configurations that optimize SAR reduction while avoiding unnecessary structural complexity
Solution Approach 2:
The second ground conductor partially overlaps with the antenna element rather than fully covering it, providing sufficient SAR reduction through partial shielding while reducing the overall complexity and material requirements of the ground plane structure
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 effectively reduces SAR values while maintaining radiation efficiency, allowing for a compact form factor in wireless communication devices without the need for increased spacing between the antenna and the device casing.
Implementation Method 1
a second ground conductor electrically connected to the first ground conductor is formed in a different layer from the first ground conductor, wherein the second ground conductor has a shield part that partially overlaps with the antenna element part
Data Source
AI summary
An antenna includes: a substrate on or in which an antenna element part having an open end, a signal line connected to the antenna element part, and a first ground conductor connected to the antenna element part are formed; and a printed wiring board in which a second ground conductor electrically connected to the first ground conductor is formed in a different layer from the first ground conductor, wherein the second ground conductor has a shield part that partially overlaps with the antenna element part including a connection part between the antenna element part and the signal line and a connection part between the antenna element part and the first ground conductor and does not overlap with the open end of the antenna element part when viewed from a normal direction of the printed wiring board.