Wireless Antenna Using Battery as Ground Plane for Compact Devices
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Solution Overview
Problem
The challenge in designing antennas for small wireless devices, such as earbuds and hearing aids, is to accommodate the half-wavelength electrical length required for efficient communication while maintaining a compact form-factor, as the wavelength of RF signals exceeds the device size, and existing antennas are influenced by dielectric materials and nearby objects.
Innovation Solution
The antenna design incorporates a loop structure with two conductive portions and feed points, where the first portion is parallel and the second portion is perpendicular to the ground-plane, allowing for different current densities to handle both far-field transverse and surface waves, enabling efficient communication in both on-body and off-body modes without increasing the device's size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional antenna design is used, then the antenna can achieve efficient communication, but the device size must be large enough to accommodate the half-wavelength electrical length
Solution Approach 1:
The patent embeds the antenna structure within existing device components, specifically utilizing the battery as the first conductive structure and integrating the antenna conductor around it. This nesting approach allows the antenna to achieve its required electrical length without adding external volume to the device.
Solution Approach 2:
The patent transitions from a planar antenna layout to a three-dimensional configuration by wrapping the antenna conductor around the battery in a spiral or loop pattern. This dimensional change enables the antenna to achieve the necessary half-wavelength electrical length within a compact volume by utilizing vertical and radial space rather than only horizontal space.
2Volume of moving object
If the antenna structure is made compact, then the device size is reduced, but the antenna performance is influenced by dielectric materials and nearby objects
Solution Approach 1:
The patent creates different current density regions along the antenna conductor by varying its proximity to the battery and ground plane. The first portion of the antenna conductor that is closer to the battery experiences different current density compared to portions farther away, allowing optimized performance in different spatial zones while maintaining compact dimensions.
Solution Approach 2:
The patent introduces a ground plane as an intermediary structure between the antenna conductor and the device housing. This ground plane serves as a reference plane that stabilizes the antenna's electromagnetic field distribution, reducing the adverse effects of nearby dielectric materials and objects on antenna performance.
3Device complexity
If a single conductive structure is used, then the structure is simple, but it cannot handle both far-field transverse and surface waves effectively
Solution Approach 1:
The patent designs the antenna conductor to perform multiple functions: it serves as both the radiating element for far-field transverse waves and as a surface wave guide when positioned near the battery. The same conductive structure adapts its function based on its spatial relationship with the battery and ground plane, eliminating the need for separate antenna elements for different wave modes.
Solution Approach 2:
The patent creates a dynamic current distribution along the antenna conductor where the current density varies depending on the operating mode. During far-field communication, current flows primarily along the outer path, while during surface wave propagation, current couples with the battery to create a distributed current pattern, allowing the structure to adapt to different operational requirements.
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 allows for effective communication in both on-body and off-body modes, supporting various wireless standards and frequencies, while maintaining a compact form-factor by utilizing the device's existing components like batteries and printed circuit boards, ensuring minimal space usage and efficient power transfer.
Implementation Method 1
the first portion of the second conductive structure is configured to be responsive to an RF far-field transverse wave
Implementation Method 2
the second portion of the second conductive structure is configured to be responsive to an RF surface wave
Implementation Method 3
the first portion of the second conductive structure is configured to be in galvanic contact with the first portion of the first conductive structure
Data Source
AI summary
Example antenna configured to be coupled to a first conductive structure having a first portion and a second portion, the antenna including: a second conductive structure having a first portion and a second portion; wherein the first portion of the second conductive structure is configured to be coupled to the first portion of the first conductive structure; a first feed point configured to be coupled to the second portion of the first conductive structure; wherein the first portion of the first conductive structure is configured to carry the RF signal current with a first current density; wherein the first portion of the second conductive structure is configured to carry the RF signal current with a second current density; wherein the first and second current densities are different.