Wearable Antenna Isolation Using High-Permittivity Substrates
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Solution Overview
Problem
Designing antennas for wearables is challenging due to the human body's lossy and conductive nature, which affects antenna performance, and the limited space available, often conflicting with the need for small size and durable materials like metal.
Innovation Solution
A wearable antenna is designed using a microwave dielectric substrate with a high relative permittivity, an electrically conductive patch, and a ground plane, enclosed in a non-conductive material, with a microstrip feed line and U-shaped slot to optimize size and efficiency, and is insulated from the wearable body to mitigate body effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the antenna is placed in close proximity to or in direct contact with the skin, then the antenna can be integrated into the wearable device, but the human body's lossy and conductive nature significantly degrades antenna performance
Solution Approach 1:
A non-conductive spacer or substrate is introduced between the antenna and the human body to act as an intermediary layer. This mediator prevents direct contact with the lossy body while maintaining integration, thereby preserving antenna performance through improved isolation.
2Volume of moving object
If the antenna size is reduced to fit limited wearable space, then the wearable device becomes more compact, but antenna performance and radiation efficiency deteriorate
Solution Approach 1:
The antenna design utilizes high-permittivity dielectric materials to change the electrical parameters of the substrate. This allows the antenna to achieve resonant frequencies and maintain radiation efficiency in a physically smaller volume by concentrating electromagnetic energy more effectively.
Solution Approach 2:
The antenna employs composite structures combining conductive materials with high-permittivity dielectric substrates. This composite approach enables compact dimensions while maintaining performance through enhanced electromagnetic field confinement and controlled impedance matching.
3Strength
If metal or high conductivity material is used for the wearable body to provide durability and luxury appearance, then the wearable device gains durability and aesthetic appeal, but additional challenges arise in antenna design due to electromagnetic interference
Solution Approach 1:
The antenna system is extracted and isolated from the conductive wearable body through non-conductive mounting structures and spacing. This separation removes the harmful electromagnetic interaction between the metal body and antenna, simplifying the antenna design despite the presence of conductive materials in the wearable device.
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 solution enables a compact, efficient antenna that operates effectively in the 2.4-2.48 GHz range, allowing for wearables to be made from conductive materials without compromising performance, and can be integrated into various forms like smart jewelry or wristbands.
Implementation Method 1
a microwave dielectric substrate with a high relative permittivity
Data Source
AI summary
A wearable device includes a wearable body that in use is worn on or proximate a skin of a wearer and a wearable antenna embedded in the wearable body and insulated from the wearable body. The wearable antenna includes a microwave dielectric substrate having a first major surface, a second major surface opposed to the first major surface, and a relative permittivity of at least 90. An electrically conductive patch is disposed on the first major surface, a feed line is connected to a feed point of the electrically conductive patch, and an electrically conductive ground plane is disposed on a far side of the second major surface relative to the first major surface.