Mechanically Modulated Loopstick Antenna Using Magnetoelastic Core

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Solution Overview

Problem

Existing loopstick antennas below 100 MHz face challenges in achieving wide bandwidth and efficient transmission due to high voltages and complexity associated with direct antenna modulation, and the physical size of antennas for very low frequency (VLF) and ultra low frequency (ULF) electromagnetic waves becomes impractically large.

Innovation Solution

A mechanically actuated magnetoelastic material is used in the core of a loopstick antenna to modulate permeability, allowing for rapid modulation of the magnetic field without high voltage switching elements, enabling large bandwidth transmission by varying the mechanical stress applied to the magnetoelastic material using mechanical actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If direct antenna modulation is used to achieve wide bandwidth transmission, then bandwidth is improved, but high voltages are generated that increase complexity and cost of switching elements

Engineering Contradiction:

ImprovebandwidthVSAvoidcomplexity of switching elements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces electrical switching elements with mechanical actuators that apply physical stress to the magnetoelastic core material. This mechanical substitution avoids high voltage switching while achieving the same bandwidth modulation effect through stress-induced permeability changes in the core material.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the core material by applying mechanical stress to alter its magnetic permeability. This parameter change allows bandwidth modulation without requiring high voltage switching elements, as the stress-induced permeability variation directly modulates the antenna's resonant frequency and bandwidth.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If mechanical actuators are used to modulate permeability, then bandwidth transmission is improved, but device complexity changes

Engineering Contradiction:

Improvebandwidth transmissionVSAvoidcomplexity of transmitter

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the high voltage switching elements from the transmitter architecture, replacing them with low-voltage mechanical actuators. This extraction simplifies the overall transmitter complexity by eliminating complex high voltage switching circuits while maintaining bandwidth transmission capabilities through mechanical permeability modulation.

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of energy

If conventional loopstick antenna design is used for VLF and ULF frequencies, then transmission efficiency is improved, but antenna size becomes impractically large

Engineering Contradiction:

Improvetransmission efficiencyVSAvoidantenna size

Core Design Contradiction:

Loss of energyVSLength of moving object

Solution Approach 1:

The patent uses magnetoelastic core material whose magnetic permeability can be dynamically changed by mechanical stress. This parameter change allows the antenna to maintain efficient transmission at VLF and ULF frequencies while keeping the physical size compact, as the stress-induced permeability variation compensates for the electrically small dimensions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic control of the core material's magnetic properties through mechanical actuation. This dynamic permeability modulation allows the antenna to adapt its electrical characteristics to maintain efficiency at very low frequencies without requiring physically large dimensions, enabling compact yet efficient VLF/ULF transmission.

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

This approach reduces the complexity and cost of the transmitter while achieving efficient and wideband signal transmission without the need for high voltage switching, and allows for compact antenna designs even at VLF and ULF frequencies.

Implementation Method 1

Methodology Applied

Scientific EffectMagnetoelastic effect: Magnetoelastic Effects

Data Source

PatentUS11271295B1Mechanically modulated loopstick antenna

Publication Date: 2022.03.08 HRL LAB

AI summary

The impedance of a loopstick antenna is directly modulated utilizing a mechanically actuated magnetoelastic material preferably placed in the core (or center) of looped wires forming the loopstick antenna. Using one or more mechanical actuators the permeability in the center of the loopstick antenna can be modulated at a rapid rate (such as with data or audio information), allowing the magnetic field outside of the antenna to be modulated at large bandwidths without requiring switches or modulators capable of high voltage thus reducing the overall complexity and cost of the transmitter. The external magnetic field is created by an AC source which is preferably impedance matched to the loopstick antenna by means of a matching network and is FM modulated according to a modulating signal applied to the one or more mechanical actuators.