RFID Strap Antenna Coupling via Magnetic and Electric Fields

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Solution Overview

Problem

Existing RFID devices typically rely on single coupling methods, such as conductive connections, electric field capacitive connections, or magnetic induction, which limit impedance matching and flexibility in adapting to different antenna configurations.

Innovation Solution

An RFID device that couples an RFID strap to an antenna using a combination of magnetic and electric fields, with a strap conductor featuring a loop section for magnetic coupling and an extension section for electric coupling, allowing for improved impedance matching and adaptability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single coupling method (conductive, electric field, or magnetic induction) is used to connect the RFID strap to the antenna, then the coupling is simple to implement, but the impedance matching is limited and adaptability to different antenna configurations is reduced

Engineering Contradiction:
Improveadaptability to different antenna configurationsVSAvoidcoupling structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple coupling methods (conductive connection, electric field coupling, and magnetic induction) into a single integrated coupling structure. The RFID strap includes both a conductive portion for direct electrical connection and a magnetic portion for inductive coupling, allowing the system to simultaneously utilize multiple coupling mechanisms to achieve better impedance matching and broader adaptability to different antenna configurations.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The coupling structure is designed to perform multiple functions simultaneously: it provides conductive connection for direct signal transmission, electric field coupling for capacitive coupling, and magnetic induction for inductive coupling. This multi-functional design allows the same RFID strap to work effectively with various antenna types and configurations without requiring separate coupling mechanisms for each case.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If conventional single-field coupling is used, then the device structure is simple, but the communication efficiency and signal transmission quality are limited due to poor impedance matching

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidcoupling mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges conductive, electric field, and magnetic induction coupling mechanisms into a unified RFID strap structure. This combination enables the system to achieve superior impedance matching by utilizing multiple coupling pathways simultaneously, thereby improving communication efficiency and signal transmission quality while maintaining a relatively simple overall device structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The RFID strap is constructed as a composite structure incorporating different materials and coupling mechanisms: conductive materials for direct electrical connection, dielectric materials for electric field coupling, and magnetic materials for inductive coupling. This composite design allows the system to leverage the advantages of each material type to achieve optimal impedance matching and reliable communication.

Inventive Principle:
Principle #40Composite materials

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 dual-field coupling approach enhances impedance matching between the RFID chip and antenna, improving communication efficiency and allowing for better adaptation to various antenna configurations and manufacturing tolerances.

Implementation Method 1

In yet another conventional design, the RFID strap and antenna of an RFID device are coupled via a magnetic induction field

Methodology Applied
Scientific EffectMagnetic induction: Electromagnetic Induction

Implementation Method 2

In another conventional design, the RFID strap and antenna of an RFID device are coupled via an electric field capacitive connection

Methodology Applied
Scientific EffectElectric field capacitive connection: Capacitance

Data Source

PatentEP3549195B1Coupling of RFID straps to antennae using a combination of magnetic and electric fields
Publication Date: 2021.10.27 AVERY DENNISON RETAIL INFORMATION SERVICES LLC
  • EP3549195B1 patent drawingFigure 1
  • EP3549195B1 patent drawingFigure 2A~2B
  • EP3549195B1 patent drawingFigure 3A~3B

AI summary

An RFID device includes an antenna and an RFID strap. The RFID strap is coupled to the antenna by a combination of magnetic and electric fields. The RFID strap includes an RFID chip and a strap conductor coupling the RFID chip to the antenna. The strap conductor has a loop section positioned generally adjacent to the antenna to magnetically couple the RFID strap to the antenna. The strap conductor also has an extension section overlapping and crossing the antenna to electrically couple the RFID strap to the antenna. By adjusting the size of the RFID strap, the configuration of the RFID strap, the degree of overlap between the extension section and the antenna, and/or the angular orientation of the RFID strap with respect to the antenna, the impedance transformation between the RFID chip and the antenna may be varied to better match the RFID chip and the antenna.