NFEMI Antenna Ferrite Shield for Small Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Small antenna constructions in devices like earbuds, hearing aids, and smart watches compromise the robustness of wireless communication links due to their size, leading to reduced reliability in near-field electromagnetic induction (NFEMI) communication.
Innovation Solution
A near-field electromagnetic induction antenna system incorporating a flexible substrate with a magnetic antenna comprising two coupled coils and an electric antenna in the form of a short loaded dipole, along with a ferrite shield to enhance magnetic flux amplification and electric field strength, is designed to improve communication reliability by confining fields near the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If small antenna constructions are used in devices like earbuds, hearing aids, and smart watches, then the device size is reduced, but the robustness of wireless communication links deteriorates
Solution Approach 1:
The patent employs a ferrite shield material with specific magnetic properties (permeability μr≥100, loss tangent tanδ≤0.4) to create a composite antenna structure. This composite construction combines the magnetic shielding properties of ferrite with conventional antenna elements, enabling small form factor antennas to achieve enhanced magnetic flux confinement and improved communication reliability despite reduced size
Solution Approach 2:
The patent optimizes key parameters including the ferrite shield thickness (0.1-2.0mm), permeability (μr≥100), and loss tangent (tanδ≤0.4) to achieve the desired balance between small antenna size and reliable communication. By carefully controlling these parameters, the antenna system maintains robust wireless links while minimizing device form factor
2Volume of moving object
If small antenna constructions are used, then device form factor is improved, but electric field strength and received voltage deteriorate
Solution Approach 1:
The ferrite shield material serves dual functions: it confines magnetic flux to enhance coupling efficiency while its specific electromagnetic properties (high permeability, low loss tangent) prevent excessive energy dissipation. This composite approach maintains strong electric field strength and received voltage despite the reduced antenna construction size
Solution Approach 2:
The ferrite shield is strategically positioned adjacent to the antenna elements where magnetic flux concentration is most beneficial. This localized placement ensures that electric field strength is enhanced precisely where needed for communication, while maintaining the overall small form factor of the antenna construction
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 antenna system increases electric field strength in transmit mode and received voltage in receive mode, enhancing the reliability of wireless body communication, particularly in small form factor devices like smartwatches and earbuds.
Implementation Method 1
Near-field electromagnetic induction (NFEMI) communication utilizes non-propagating quasi-static fields
Implementation Method 2
Each region is a different type of material, has a different thickness, and/or has other non-uniformities (e.g., different permeabilities) to concentrate magnetic field lines
Data Source
Figure 1
Figure 2
Figure 3
AI summary
One example discloses a near-field electromagnetic induction (NFEMI) antenna, including: an electric antenna including a first electrically conductive surface; a magnetic antenna including a first coil (L1) coupled to a second coil (L2); a first feeding connection coupled to one end of the first coil; a second feeding connection coupled to another end of the first coil and one end of the second coil; wherein a another end of the second coil is connected to the electrically conductive surface; and a magnetic permeable material coupled to one side of the magnetic antenna and configured to be placed between the magnetic antenna and a set of electric components.