Harmonic RFID Tag System for Interference-Resistant Sensing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current RFID technologies face challenges in environments with interference, such as underground or underwater applications, where signal strength is weakened due to material reflections, leading to reduced signal-to-noise ratio and difficulty in transmitting data effectively.

Innovation Solution

The implementation of a harmonic RFID tag system that generates harmonics of the interrogator's frequency, incorporating a non-linear transmission line and energy harvesting unit, allows for robust communication by transmitting sensor data and ID information, reducing interference and increasing signal strength through tailored harmonic generation and dual-band antenna designs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If passive RFID tags are used to operate without power sources for long lifetime applications, then the lifetime is extended and accessibility requirements are reduced, but the ability to actively control transmission and handle interference is limited

Engineering Contradiction:

ImproveRFID tag lifetimeVSAvoidcommunication reliability in interference environments

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

A battery is introduced as an intermediary power source that enables the RFID tag to actively control its transmission. The battery allows the tag to generate its own RF signals and modulate responses, providing the power necessary to overcome interference from reflective materials while maintaining the long lifetime benefit of passive operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transitions from static passive RFID operation to dynamic active transmission control. The RFID tag with battery power can dynamically adjust transmission timing, signal strength, and modulation patterns to optimize communication reliability in challenging electromagnetic environments with reflective interference.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If traditional RFID frequencies are used for communication, then simplicity is maintained, but signal strength is weakened by material reflections causing radio interference

Engineering Contradiction:

Improvesystem simplicityVSAvoidradio interference from material reflections

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The system changes the frequency parameter by transmitting at the second harmonic (2f0) of the original RFID frequency f0. This frequency multiplication approach allows the signal to bypass reflective interference that affects the fundamental frequency, while the interrogator can still detect the harmonic response through appropriate signal processing.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the RFID tag transmits at the same frequency as the interrogator, then communication is straightforward, but interference from reflective materials creates signal degradation

Engineering Contradiction:

Improvecommunication easeVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The system moves from operating in the fundamental frequency dimension to the harmonic frequency dimension. By transmitting at 2f0 instead of f0, the RFID tag operates in a different frequency dimension where reflective interference is reduced, allowing information to be transmitted with better signal-to-noise ratio while maintaining communication functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 approach enhances the signal-to-noise ratio and enables reliable data transmission in challenging environments, such as underground or underwater, by using harmonics to bypass interference and provide a unique signature for secure communication.

Implementation Method 1

incorporating a non-linear transmission line and energy harvesting unit, allows for robust communication by transmitting sensor data and ID information, reducing interference and increasing signal strength through tailored harmonic generation

Methodology Applied

Scientific EffectNon-linear transmission:

Implementation Method 2

incorporating a non-linear transmission line and energy harvesting unit, allows for robust communication

Methodology Applied

Scientific EffectEnergy harvesting:

Data Source

PatentUS10929620B2Harmonic RFID tag-reader system for long range sensing identification and security

Publication Date: 2021.02.23 BOARD OF TRUSTEES OPERATING MICHIGAN STATE UNIV

AI summary

A harmonic tag system includes a harmonic tag and a first antenna configured to receive a fundamental signal and transmit an identifier of the harmonic tag at a fundamental frequency. The harmonic tag system includes an energy harvesting unit configured to convert the fundamental signal into power. The power activates a sensor. The harmonic tag system also includes a harmonic doubler configured to generate a harmonic signal at a harmonic frequency based on (i) the fundamental signal and (ii) a sequence. The harmonic tag system further includes a digital modulation unit configured to selectively trigger an activation of the harmonic doubler. The harmonic doubler is triggered sequentially in an off state and an on state, and the digital modulation unit produces the sequence. The harmonic tag system also includes a second antenna configured to transmit data of the sensor at the harmonic frequency.