NFEMI Antenna Multi-Coil Coupling for Wearable Range

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Solution Overview

Problem

Existing near-field electromagnetic induction (NFEMI) antennas face challenges in generating strong enough magnetic and electric fields near the human body for reliable wireless communication, particularly in wearable devices, as they tend to confine energy close to the body, limiting the communication range and signal strength.

Innovation Solution

The proposed NFEMI antenna system includes a magnetic antenna with three coupled coils (two bifilar wound and one non-bifilar) and an electric antenna with conductive surfaces, configured to carry time-varying currents in the same direction, enhancing coupling coefficients to increase magnetic and electric field strengths, thereby improving communication link reliability and range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing NFEMI antenna configuration is used, then device complexity is kept simple, but magnetic and electric field strength is insufficient for reliable wireless communication

Engineering Contradiction:
Improvewireless communication reliabilityVSAvoidantenna structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple coils (first coil, second coil, and third coil) into a unified magnetic antenna structure that works together to generate enhanced magnetic and electric fields. The first and second coils are bifilar wound and mutually coupled, while the third coil is coupled to the second coil, creating a merged structure that produces stronger fields than individual coils could achieve alone, thereby improving wireless communication reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The magnetic antenna is segmented into multiple distinct coil components (first coil, second coil, third coil) with specific coupling relationships. This segmentation allows each coil to contribute differently to the overall field generation, with the bifilar wound first and second coils providing strong coupling and the third coil extending the magnetic field strength, achieving reliable communication through coordinated segment performance.

Inventive Principle:
Principle #1Segmentation

2Length of moving object

If energy is confined close to the body, then wearable device integration is improved, but communication range is limited

Engineering Contradiction:
Improvecommunication rangeVSAvoidenergy confinement
Core Design Contradiction:
Length of moving objectVSLoss of energy

Solution Approach 1:

The patent changes the electromagnetic field generation parameters by using a multi-coil configuration with specific coupling coefficients. The first coil has a first coupling coefficient with the second coil and a second coupling coefficient with the third coil, allowing optimization of field distribution. This parameter optimization enables the antenna to extend energy distribution beyond immediate body proximity while maintaining wearable integration, thereby extending communication range.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If signal strength is increased, then communication reliability is improved, but energy consumption increases

Engineering Contradiction:
Improvecommunication link reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent converts the potential harm of energy loss through multiple coil couplings into a benefit by optimizing the coupling coefficients. The first coil's dual coupling with the second and third coils creates a configuration where energy is efficiently distributed across the magnetic antenna structure. This converts what could be energy loss into enhanced magnetic field strength and improved communication reliability, achieving stronger signals without proportional energy consumption increases.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 results in stronger magnetic and electric fields, increased voltage gain, and improved communication reliability for wearable devices, extending the communication range and enhancing signal strength, suitable for applications like healthcare and consumer lifestyle products.

Implementation Method 1

a first coil and a second coil, wherein the first coil and the second coil are mutually coupled

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Near-field electromagnetic induction (NFEMI) antenna

Methodology Applied
Scientific EffectNear-field electromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3389135B1Near-field electromagnetic induction (NFEMI) antenna
Publication Date: 2020.05.20 NXP BV
  • EP3389135B1 patent drawingFigure 1A
  • EP3389135B1 patent drawingFigure 1B
  • EP3389135B1 patent drawingFigure 2A

AI summary

Example near-field electromagnetic induction (NFEMI) antenna, including: an electric antenna having a first surface and a second surface; a magnetic antenna having a first, second and third coils; a first feeding connection coupled to one end of the first coil and the first surface; a second feeding connection coupled to another end of the first coil and coupled to one end of the second coil; wherein another end of the second coil is coupled to one end of the third coil; wherein another end of the third coil is coupled to the second surface; wherein the first, second and third coils are configured to carry a time varying current from the first and second feeding connections in a same direction; wherein the first and second coils are configured to have a first coupling coefficient; and wherein the first and third coils are configured to have a second coupling coefficient.