Passive Wireless Sensor Frequency Conversion Antenna Size

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Solution Overview

Problem

Existing passive wireless sensors face limitations in operating at lower frequencies due to large antenna sizes, which overwhelm physical constraints on sensor package size, and current technologies are not applicable for all passive sensor applications.

Innovation Solution

A passive wireless sensor system that uses an antenna to receive a combined signal with a low frequency modulating signal and a high frequency carrier wave, where a demodulator extracts the modulating signal, a transducer produces an output signal with a time delay indicative of a sensed property, and a modulator combines the output signal with the carrier wave for broadcasting, allowing for reduced antenna size and operation at frequencies between 0.1 MHz and 40 MHz.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If passive wireless sensors operate at lower frequencies, then the sensing capability is improved for various applications, but the antenna size becomes too large for compact sensor packages

Engineering Contradiction:

Improvefrequency rangeVSAvoidantenna size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent transitions from direct low-frequency operation to a dimensionality-changed approach where low-frequency sensing is performed, then the signal is up-converted to high-frequency for wireless transmission. This separates the sensing dimension (low frequency) from the transmission dimension (high frequency), allowing compact antennas while maintaining low-frequency sensing capabilities

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the frequency parameter dynamically through signal processing. The sensor operates at low frequency for sensing, then uses frequency conversion to transmit at high frequency. This parameter transformation resolves the contradiction between low-frequency adaptability and compact antenna requirements

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If SAW devices operate at higher frequencies, then the antenna size is reduced, but the applicability to all passive sensor applications is limited

Engineering Contradiction:

Improveantenna sizeVSAvoidapplication range

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent segments the sensing and transmission functions into separate stages with different frequency requirements. The sensing stage operates at low frequency for broad application applicability, while the transmission stage operates at high frequency for compact antenna size. This functional segmentation resolves the contradiction between antenna size and application range

Inventive Principle:

Principle #1Segmentation

3Reliability

If passive sensors use low frequency operation, then the sensing capability is improved, but the antenna size becomes too large

Engineering Contradiction:

Improvesensing capabilityVSAvoidantenna length

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent introduces frequency conversion as an intermediary process between low-frequency sensing and high-frequency transmission. This intermediary mechanism allows the sensor to benefit from low-frequency sensing capabilities while using high-frequency signals for compact wireless communication, resolving the contradiction between sensing reliability and antenna dimensions

Inventive Principle:

Principle #24Intermediary (Mediator)

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 the development of compact passive wireless sensors capable of operating at lower frequencies, suitable for various applications, including ultrasonic flow meters, by minimizing antenna size while maintaining effective signal processing and parameter sensing.

Implementation Method 1

an antenna receives a combined signal that includes a low frequency modulating signal between 0.1 MHz and 40 MHz modulated on a high frequency carrier wave

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a transducer receives the extracted modulating signal and produces an output signal with a time delay indicative of a property to be sensed

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11567039B2Passive wireless sensor

Publication Date: 2023.01.31 MARQUETTE UNIVERSITY

AI summary

Passive wireless sensors include an antenna. The antenna receives a combined signal. The combined signal includes a low frequency modulating signal modulated on a high frequency carrier wave. A demodulator receives the combined signal and extracts the modulating signal. A sensor receives the extracted modulating signal and produces an output signal with a time delay indicative of a property to be sensed. A modulator receives the output signal and the high frequency carrier wave and modulates the output signal onto the high frequency carrier wave to create a combined output signal broadcast by the antenna.