Multiband RF Harvesting with Switched Narrowband Rectifier Chains

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Solution Overview

Problem

Conventional RF harvesting methods are limited by their narrowband capabilities, making them ineffective in mobile sensing scenarios due to geographical fluctuations in spectral occupation, occlusion, and multipath fading, and they struggle with bootstrapping and energy efficiency across a wide spectrum.

Innovation Solution

A multiband harvesting system using a single wideband antenna coupled with multiple narrowband rectifier chains, each with a bandpass filter and matching network, and a switching network to combine outputs efficiently, allowing for energy harvesting across a wide range of frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a single wideband antenna is used for harvesting, then the bandwidth coverage is improved, but the impedance matching quality deteriorates

Engineering Contradiction:

Improvebandwidth coverageVSAvoidimpedance matching quality

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent divides the wideband harvesting system into multiple narrowband rectifier chains, each tuned to a specific frequency band. Each chain includes a bandpass filter and matching network optimized for its designated band, allowing the system to maintain high impedance matching quality across multiple bands while covering a wide overall bandwidth.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The single wideband antenna serves multiple functions by capturing RF energy across a broad frequency spectrum, feeding multiple narrowband rectifier chains that each process different frequency bands. This multi-functional approach allows one antenna to replace what would traditionally require multiple specialized antennas.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple antennas are used for multiband harvesting, then the frequency coverage is improved, but the device complexity increases

Engineering Contradiction:

Improvefrequency coverageVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges multiple narrowband rectifier chains into a single integrated multiband harvester system that shares a common wideband antenna and power management infrastructure. This consolidation achieves multiband frequency coverage while reducing the overall system complexity compared to using completely separate harvesting systems for each band.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If a narrowband rectifier chain is used, then the rectification efficiency is improved, but the spectral adaptability deteriorates

Engineering Contradiction:

Improverectification efficiencyVSAvoidspectral adaptability

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent segments the spectral coverage into multiple narrowband rectifier chains, each optimized for high rectification efficiency at its specific frequency band. By dividing the wideband operation into multiple narrowband segments, the system maintains high efficiency in each segment while achieving broad overall spectral adaptability through the combination of all segments.

Inventive Principle:

Principle #1Segmentation

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 system achieves efficient energy harvesting across various frequency bands, overcoming the limitations of narrowband harvesters by providing a stable power source in diverse spectral environments and enabling mobile RF harvesting applications.

Implementation Method 1

Each rectifier chain may include a bandpass filter, a tuned impedance matching network, and a rectifier

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Implementation Method 2

Each rectifier chain may include a bandpass filter, a tuned impedance matching network, and a rectifier

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 3

Each rectifier chain may include a bandpass filter, a tuned impedance matching network, and a rectifier

Methodology Applied

Scientific EffectImpedance matching:

Data Source

PatentUS9979240B2Multiband harvesting systems and methods including switching networks

Publication Date: 2018.05.22 UNIV OF WASHINGTON

AI summary

Examples described herein include systems and methods for multiband harvesting. An example system may include a single wideband antenna followed by several narrowband rectifier chains. Each rectifier chain may include a bandpass filter, a tuned impedance matching network, and a rectifier. The outputs of the rectifiers may be combined using a summation network. The summation network, which may be a diode summation network, may in some examples provide good performance even when only a subset of the narrowband harvesters (e.g. a subset of the rectifier chains) is excited.