Auto-configurable RFID Antenna Extender with Self-Tuning Circuit

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Solution Overview

Problem

Existing RFID antenna extenders require manual tuning and external power sources, making them costly and difficult to install, as they struggle to maintain resonance frequency in varying environments, leading to reduced read/write distances and efficiency.

Innovation Solution

An autonomous antenna extender with a variable-frequency oscillating circuit and a processing unit that measures voltage across its terminals, automatically adjusting its resonant frequency to match the RFID station, allowing self-tuning and electromagnetic coupling without external power or assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual tuning and external power sources are used for RFID antenna extenders, then frequency tuning can be achieved, but installation becomes costly and difficult

Engineering Contradiction:
Improvefrequency tuning precisionVSAvoidinstallation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The extender automatically measures the voltage across its terminals and adjusts its own resonant frequency without external assistance. The processing unit controls the variable capacitor to achieve optimal tuning autonomously, eliminating the need for manual intervention or external power sources during installation.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The extender dynamically changes its electrical parameters by adjusting the capacitance value through the variable capacitor. This allows the resonant frequency to be automatically tuned to match the RFID station by varying the electrical parameter (capacitance) based on measured voltage conditions.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If shielding is placed around the extender to maintain frequency stability, then frequency variations are reduced, but cost and installation difficulty increase

Engineering Contradiction:
Improvefrequency stabilityVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The processing unit continuously measures the voltage across the terminals of the second oscillating circuit and uses this feedback information to adjust the resonant frequency of the first oscillating circuit. This closed-loop feedback mechanism maintains frequency stability without requiring physical shielding.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces the mechanical/physical solution (shielding) with an electronic control solution. Instead of using physical barriers to prevent frequency variations, the system uses electronic measurement and automatic adjustment of electrical parameters to maintain frequency stability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the extender is tuned manually for each application, then frequency matching is achieved, but installation time and expert assistance are required

Engineering Contradiction:
Improvefrequency matching accuracyVSAvoidinstallation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The extender autonomously performs the tuning process by measuring terminal voltage and automatically adjusting its resonant frequency through the variable capacitor controlled by the processing unit. This self-service capability eliminates the need for expert assistance and reduces installation time significantly.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The extender automatically performs the frequency tuning action immediately upon installation without waiting for manual configuration. The system proactively measures and adjusts its parameters to achieve optimal matching with the RFID station before actual use begins.

Inventive Principle:
Principle #10Preliminary action

4Device complexity

If environment variations are not compensated, then device simplicity is maintained, but read/write distance is reduced due to frequency mismatch

Engineering Contradiction:
Improvedevice simplicityVSAvoidread/write distance
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The extender employs dynamic adjustment of its resonant frequency through the variable capacitor, allowing it to adapt to environmental variations. This dynamic parameter adjustment maintains optimal frequency matching with the RFID station despite changes in the operating environment, preserving read/write distance without adding complex shielding structures.

Inventive Principle:
Principle #15Dynamics

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

Enables simple, quick installation and optimal frequency tuning, increasing the detection area and maintaining communication efficiency across different environments without user intervention or external devices.

Implementation Method 1

The LC oscillating circuit of the extender is therefore electromagnetically coupled with the antenna of the RFID station

Methodology Applied
Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

the processing unit which is powered by the energy supplied by the second oscillating circuit when the extender is placed close to the read/write station

Methodology Applied
Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 3

To work well, an extender must be tuned to the same resonant frequency as the read/write station

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP2507739B1Auto-configurable RFID antenna extension
Publication Date: 2014.12.03 SCHNEIDER ELECTRIC IND SAS
  • EP2507739B1 patent drawingFigure 1~3

AI summary

The invention relates to an antenna extender (20) intended to be coupled electromagnetically to an RFID read/write station (10), said extender (20) comprising a first circuit (21) oscillating at variable frequency and a second oscillating circuit (31) coupled to the first oscillating circuit (21). The extender comprises a processing unit (35) which is powered by energy supplied by the second oscillating circuit when the extender is placed close to the read/write station (10). The processing unit includes means for measuring voltage at the terminals of the second oscillating circuit and control means that can be used to vary the resonance frequency of the first oscillating circuit as a function of the value of the measured voltage, in order to optimise the frequency tuning between the extender and the read/write station.