Magnetoelectric VLF Antenna Using Strain-Mediated Coupling
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Solution Overview
Problem
Existing VLF communication systems face challenges with large, inefficient antennas due to mechanical displacement of hard magnets, which result in low radiation efficiency and require high power for long-distance communication.
Innovation Solution
The development of compact, power-efficient magnetoelectric antennas using a thin film heterostructure with a piezoelectric core composite sandwiched between metallic glass foils, enabling strain-mediated magnetoelectric coupling for efficient transmission and reception of VLF electromagnetic waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If mechanically hard magnets are displaced to generate VLF electromagnetic waves, then electromagnetic radiation is achieved, but radiation efficiency is extremely low due to large frictional forces
Solution Approach 1:
The patent replaces the mechanical displacement system with an electromagnetic actuation system. Instead of mechanically moving hard magnets through friction-prone mechanical systems, the invention uses electromagnetic fields to directly actuate the magnetic material, eliminating the need for mechanical motors and reducing frictional losses significantly.
Solution Approach 2:
The patent changes the operating parameters by using alternating magnetic fields at VLF frequencies to induce magnetization oscillations in the magnetic material. This parameter change from mechanical displacement to electromagnetic oscillation enables efficient energy transfer and improves radiation efficiency.
2Loss of energy
If the antenna length matches a fraction of the VLF wavelength for effective transmission, then radiation efficiency improves, but the antenna becomes extremely large and impractical for mobile applications
Solution Approach 1:
The patent transitions from traditional linear antenna structures to a compact heterostructure that achieves resonant behavior through dimensional transformation. The thin-film heterostructure with layered composition creates resonant modes that enable effective VLF radiation from a compact geometry, bypassing the need for wavelength-scale physical dimensions.
Solution Approach 2:
The patent employs a composite heterostructure combining piezoelectric materials, magnetic materials, and dielectric layers. This composite structure enables magnetoelectric coupling that enhances radiation efficiency while maintaining a compact form factor, allowing the antenna to be much smaller than the wavelength while still achieving effective VLF transmission.
3Reliability
If high power transmitters are used for long distance VLF communication, then communication range is extended, but power consumption increases significantly
Solution Approach 1:
The patent changes the operating parameters by utilizing resonant frequencies in the VLF range (3-30 kHz) where the magnetoelectric heterostructure exhibits enhanced coupling efficiency. This parameter optimization allows for lower power consumption while maintaining communication range, as the resonant structure naturally amplifies the radiated signal.
Solution Approach 2:
The magnetoelectric composite heterostructure enables efficient energy conversion between electric and magnetic fields, reducing power losses. The coupled resonance between piezoelectric and magnetic components creates a synergistic effect that enhances radiation efficiency and extends communication range at lower power levels compared to conventional single-material antennas.
4Speed
If mechanical motors are used to achieve high linear or angular velocity at 10 kHz or above, then electromagnetic wave generation is enabled, but the system becomes limited by the angular speed capability of mechanical motors
Solution Approach 1:
The patent eliminates mechanical motors entirely by using electromagnetic fields to directly induce magnetization oscillations in the magnetic material at the desired frequency. This substitution of mechanical actuation with electromagnetic actuation enables achievement of high frequencies (10 kHz and above) without being constrained by mechanical motor speed limitations.
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 provides a compact, mobile, and power-efficient means for transmitting and receiving VLF electromagnetic waves, achieving significant improvements in radiation efficiency and allowing communication over long distances with low power consumption.
Implementation Method 1
oscillating mechanical strain produced in the piezoelectric material by an AC voltage applied to the first pair of electrodes
Implementation Method 2
strain-mediated magnetoelectric coupling. This leads to magnetization oscillation in the glass foil material and consequent radiation of the VLF electromagnetic waves
Implementation Method 3
In a receiving mode, the heterostructure senses magnetic components of VLF electromagnetic waves arriving at the antenna and, in concert with the core, produces a piezoelectric output voltage
Data Source
AI summary
Compact and power efficient acoustically actuated magnetoelectric antennas for transmitting and receiving very low frequency (VLF) electromagnetic waves utilize magnetoelectric coupling in a magnetic/piezoelectric heterostructure to provide voltage control of magnetization in transmission mode and magnetic control of electric polarization in receiving mode. The magnetoelectric antennas provide a power efficiency enhanced by orders of magnitude compared to magnetically or mechanically switching the magnetization. The antennas can be used in groups or arrays and can be combined to form VLF communication systems.