Near Field RFID Probe Tuning via Switch Capacitor Networks

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

RFID tracking systems face challenges in maintaining consistent power transfer due to shifts in resonant frequency caused by changes in distance and metal objects in the environment, which deteriorate communication between the RFID probe and tag.

Innovation Solution

A tunable near-field RFID probe with a resonant coil and switch capacitor networks that adjust capacitance to maintain a predetermined resonant frequency, using RF switches and capacitors to dynamically tune the resonant frequency in real-time, ensuring optimal power transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the resonant coil operates at a fixed resonant frequency, then the RFID system can maintain stable power transfer under ideal conditions, but the power transfer deteriorates when environmental changes (distance, metal objects) cause frequency shifts

Engineering Contradiction:

Improvepower transfer stabilityVSAvoidfrequency adaptation to environmental changes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic frequency tuning by replacing fixed capacitors with switchable capacitor networks. The resonant coil's total capacitance can be dynamically adjusted by switching between different capacitor combinations, allowing the resonant frequency to adapt in real-time to environmental changes such as distance variations and metal object interference, thus maintaining reliable power transfer.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameter (capacitance) of the resonant coil by switching between different capacitor configurations. By altering the capacitance value through the switch capacitor networks, the resonant frequency is adjusted to compensate for environmental disturbances, resolving the contradiction between stability and adaptability.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If switch capacitor networks are added to tune the resonant frequency, then frequency adaptability is improved, but the device complexity increases

Engineering Contradiction:

Improveresonant frequency tuning capabilityVSAvoidprobe structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the capacitance adjustment function into multiple discrete switch capacitor networks, each capable of providing specific capacitance values. This segmentation allows for precise frequency tuning through combination of switched capacitors, achieving complex frequency adaptation while maintaining modular and manageable circuit architecture.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the resonant frequency is continuously adjusted to maintain optimal power transfer, then communication reliability is improved, but the energy consumption increases

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidenergy consumption for frequency tuning

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic monitoring of the RFID communication quality and adjusts the resonant frequency only when deviations are detected. This periodic action approach maintains communication reliability by tuning only when necessary, rather than continuous adjustment, thereby reducing unnecessary energy consumption while preserving communication effectiveness.

Inventive Principle:

Principle #19Periodic action

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 effectively stabilizes power transfer between the RFID probe and tag by continuously adjusting the resonant frequency, reducing the impact of environmental changes and maintaining reliable communication.

Implementation Method 1

a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The switching of the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing a resonant frequency of the resonant coil

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS10855256B2Near field RFID probe with tunning

Publication Date: 2020.12.01 NORTHROP GRUMMAN SYSTEMS CORP

AI summary

A near field radio-frequency identification (“RFID”) probe includes a probe tip comprising a resonant coil configured to communicate with an RFID compatible device at a predetermined resonant frequency. The near field RFID probe further includes a plurality of switch capacitor networks each comprising a capacitor and an RF switch, wherein switching the plurality of switch capacitor networks changes the capacitance of the resonant coil, thereby changing the resonant frequency of the resonant coil. The near field RFID probe further includes a probe control module configured to adjust the resonant frequency of the resonant coil to maintain the predetermined resonant frequency by switching the switch capacitor networks responsive to detecting that the resonant frequency of the resonant coil has deviated from the predetermined resonant frequency.