Core-Shell Magnetic Material for GHz Antenna Miniaturization
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Solution Overview
Problem
Current magnetic materials fail to effectively control magnetic permeability (μ′ and μ″) at high frequencies, leading to increased transmission losses and thermal instability in high-frequency communication devices, particularly in GHz bands, where existing materials lack sufficient insulation and thermal stability.
Innovation Solution
A core-shell magnetic material is developed, comprising magnetic metal particles coated with an oxide layer and additional oxide particles, using metals like Fe, Co, and Ni, and nonmagnetic metals such as Al and Si, with carbon or nitrogen, to enhance magnetic permeability and thermal stability, while maintaining low μ″ and high μ′ characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ferrite or amorphous alloy magnetic materials are used at high frequencies (1 MHz or higher), then low magnetic loss (low μ″) and high magnetic permeability (high μ′) are achieved in the range of 1 MHz to 10 MHz, but the magnetic permeability real part μ′ drops in the higher frequency range of 10 MHz or higher
Solution Approach 1:
The patent uses a composite structure consisting of magnetic metal particles (Fe, Co, Ni) coated with an oxide layer containing nonmagnetic metals (Al, Si). This composite material combines the high magnetic permeability of magnetic metals with the high-frequency stability and insulation properties of oxide coatings, resolving the contradiction between maintaining high μ′ and achieving low μ″ at GHz frequencies.
Solution Approach 2:
The patent changes the material parameters by incorporating nonmagnetic metals (Al, Si) into the oxide coating layer and controlling their atomic ratios. This parameter adjustment optimizes the magnetic characteristics at high frequencies, maintaining stable μ′ and low μ″ in the GHz range where conventional materials fail.
2Reliability
If thin film techniques such as sputtering are used to manufacture inductance elements, then excellent characteristics in high frequency bands are achieved, but large equipment is necessary and film thickness must be controlled precisely, resulting in high cost and low yield
Solution Approach 1:
The patent replaces expensive thin film manufacturing processes with a more economical approach using magnetic metal particles with oxide coatings. This particle-based method eliminates the need for large-scale thin film equipment and precise film thickness control, significantly reducing manufacturing costs while maintaining high-frequency performance.
3Reliability
If thin film technique is used to manufacture inductance elements, then excellent high frequency characteristics are achieved, but thermal stability for long time of magnetic characteristics at high temperature and high moisture is insufficient
Solution Approach 1:
The oxide coating layer acts as an intermediary between the magnetic metal particles and the external environment (high temperature and moisture). This coating layer provides thermal stability and protects the magnetic metal core, maintaining magnetic characteristics under harsh conditions while preserving high-frequency performance.
Solution Approach 2:
The composite structure of magnetic metal particles coated with oxide layers containing nonmagnetic metals provides both high-frequency characteristics and thermal stability. The oxide coating protects the magnetic metal from thermal degradation and moisture, solving the thermal stability problem of thin film techniques.
4Volume of moving object
If dielectric ceramics are used for antenna miniaturization, then space can be reduced, but dielectric loss increases causing large transmission loss and reduced transmission/reception sensitivity
Solution Approach 1:
The patent uses magnetic metal particles with oxide coatings as a magnetic material for antenna applications. This magnetic material provides miniaturization capability similar to dielectric ceramics but with significantly lower transmission loss, as the magnetic material does not exhibit the same dielectric loss problems, thereby reducing energy loss while maintaining compact size.
Solution Approach 2:
The patent changes the material type from dielectric to magnetic, utilizing the magnetic properties of Fe-Co-Ni particles with oxide coatings. This parameter change enables antenna miniaturization through magnetic resonance effects while avoiding the high dielectric loss inherent in ceramic materials, thus reducing transmission loss.
5Volume of moving object
If dielectric material is used for antenna miniaturization, then space can be reduced, but the resonance frequency band is narrowed making it unpreferable for wideband antenna
Solution Approach 1:
The magnetic metal particle composite with oxide coating provides different magnetic resonance characteristics compared to dielectric materials. This enables broader resonance frequency bands and better adaptability for wideband antenna applications while maintaining miniaturization benefits.
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 core-shell magnetic material achieves reduced transmission losses, improved thermal stability, and broadened resonance frequency bands, making it suitable for high-frequency applications such as antenna devices and electromagnetic wave absorbers.
Implementation Method 1
an oxide coating layer for coating surface of at least a part of the magnetic metal particles
Implementation Method 2
the magnetic metal particle containing at least one magnetic metal selected from the group of Fe, Co, and Ni
Data Source
AI summary
The present invention provides a core-shell magnetic material having an excellent characteristic in a high frequency band, particularly, in a GHz band. The core-shell magnetic material includes: core-shell magnetic particles including magnetic metal particles and an oxide coating layer, the magnetic metal particle containing magnetic metal selected from the group of Fe, Co, and Ni, nonmagnetic metal selected from the group of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, a rare-earth element, Ba, and Sr, and an element selected from carbon and nitrogen, and the oxide coating layer being made of an oxide containing at least one nonmagnetic metal as one of the components of the magnetic metal particle; and oxide particles existing at least a part between the magnetic metal particles and containing nonmagnetic metal selected from the group of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, a rare-earth element, Ba, and Sr, and in which nonmagnetic metal/magnetic metal (atomic ratio) in the particles is higher than that in the oxide coating layer.