Antenna Device With Magnetic Layer For Signal Transmission
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Solution Overview
Problem
HF-band RFID systems face inefficiencies in signal transmission due to high mutual inductance between feed coils and coil antennas, leading to mismatched resonance frequencies and reduced communication distances.
Innovation Solution
Incorporating a magnetic layer with a specific relative permeability and thickness between the feed coil and coil antenna to maintain an appropriate coupling degree, ensuring impedance matching and efficient signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the feed coil and coil antenna are directly magnetically coupled with high degree of coupling, then the compactness is improved, but the resonance frequencies separate and signal transmission efficiency decreases
Solution Approach 1:
A magnetic layer is introduced as an intermediary component between the feed coil and coil antenna. This magnetic layer mediates the magnetic coupling between the two coils, allowing compact arrangement while preventing excessive coupling that would cause resonance frequency separation. The magnetic layer enables controlled signal transmission without direct high-degree coupling.
Solution Approach 2:
The invention controls the coupling parameters by adjusting the permeability and thickness of the magnetic layer. By changing these parameters, the degree of magnetic coupling is optimized to maintain resonance frequency alignment while achieving compact device structure. The product of relative permeability and thickness is specifically controlled to be less than 20.
2Device complexity
If the feed coil and coil antenna are directly magnetically coupled, then the device complexity is reduced, but the impedance matching becomes difficult and communication distance decreases
Solution Approach 1:
The magnetic layer serves as an intermediary that simplifies the connection structure between feed coil and coil antenna while improving impedance matching. Instead of using complex direct connection methods like flexible cables or contact pins, the magnetic layer provides a simple yet effective coupling mechanism that ensures reliable signal transmission and maintains proper impedance matching.
3Loss of energy
If a magnetic layer with high permeability and thickness is used to enhance magnetic coupling, then the signal transmission efficiency is improved, but the resonance points separate and communication distance decreases
Solution Approach 1:
The invention optimizes the magnetic layer parameters (permeability and thickness) to achieve the right balance. The product of relative permeability and thickness is controlled to be less than 20, which prevents resonance frequency separation while maintaining adequate signal transmission efficiency. This parameter control ensures that communication distance is not compromised.
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 configuration enhances signal transmission efficiency and extends communication distance while preventing excessive coupling that can cause resonance frequency separation.
Implementation Method 1
The feed coil and the coil antenna are magnetically coupled to each other via the magnetic layer
Implementation Method 2
a mutual inductance is generated between the feed coil and the coil antenna
Implementation Method 3
the resonance points of the feed coil and the coil antenna are separated from each other even if the resonance frequencies of the feed coil and the coil antenna correspond to a carrier frequency
Data Source
AI summary
An antenna device includes a feed coil connected to a feed circuit, and a coil antenna disposed near the feed coil. A ferrite sheet, in which a magnetic loss term in a usable frequency band is relatively large, is provided between the feed coil and the coil antenna. The feed coil and the coil antenna are magnetically coupled to each other via the ferrite sheet. With this configuration, signal transmission efficiency between the feed coil and the coil antenna is enhanced.