NFC Emitter With Ferrite Core Penetrates Metal Shielding
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Solution Overview
Problem
Existing NFC and RFID antennas on removable memory cards, such as microSD cards, face challenges with signal transmission due to shielding by metal components in mobile phones, leading to reduced communication efficiency and limited antenna size options.
Innovation Solution
A non-stationary magnetic field emitter with a specific dimensional relationship between the effective thread width and core radius, creating a homogeneous and intense magnetic field that penetrates through shielding, enhancing communication channel reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a flat loop antenna is used on a removable memory card, then the antenna can be placed on the available surface area, but the signal transmission is blocked by metal shielding components in mobile phones
Solution Approach 1:
The patent transitions from a two-dimensional flat loop antenna to a three-dimensional structure by winding the conductor around a cylindrical or rod-shaped core. This dimensional change allows the antenna to generate a magnetic field that extends through the shielding, overcoming the limitation of flat surface antennas blocked by metal components.
Solution Approach 2:
The patent changes the geometric parameters of the antenna by introducing a core with specific dimensions (diameter or radius between 0.2-2.0 mm) and winding the conductor around it. This parameter change transforms the antenna's field distribution characteristics, enabling the magnetic field to penetrate shielding more effectively while maintaining resonance at the required frequency.
2Volume of moving object
If the antenna size is reduced to fit on a small removable card, then the card form factor is maintained, but the antenna's signal transmission capability deteriorates
Solution Approach 1:
The patent optimizes the conductor winding parameters including the number of turns, winding density, and conductor diameter to achieve resonance at the target frequency with minimal antenna volume. By carefully controlling these parameters, the antenna maintains effective signal transmission power despite the small size constraints of removable memory cards.
Solution Approach 2:
The patent uses a composite structure consisting of a magnetic or dielectric core material combined with a conductive wire. This composite design allows the antenna to achieve enhanced magnetic field generation and signal transmission capability within a compact volume, as the core material concentrates and directs the magnetic field while the conductor provides the necessary electrical properties.
3Strength
If the conductor is wound tightly around the core, then the magnetic field intensity increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies optimal parameter ranges for the core diameter (0.2-2.0 mm) and conductor dimensions that balance magnetic field intensity with manufacturing feasibility. These parameter choices ensure that tight winding achieves the necessary field strength while remaining within achievable manufacturing tolerances for mass production.
Solution Approach 2:
The core acts as an intermediary structure that facilitates uniform conductor winding. By providing a rigid, pre-formed cylindrical or rod-shaped support, the core enables consistent winding spacing and tension, reducing the impact of manufacturing variations and achieving reliable magnetic field generation without requiring extremely precise winding control.
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 emitter enables reliable and efficient NFC communication by maintaining high magnetic field intensity and penetrability, even in shielded environments, improving communication channel performance and versatility.
Implementation Method 1
A non-stationary magnetic field emitter with a specific dimensional relationship between the effective thread width and core radius, creating a homogeneous and intense magnetic field that penetrates through shielding
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The emitter is intended to provide a contactless communication channel (particularly RFID/NFC) in miniature build space. The emitter has an oblong, at least partially ferrite core (1), the core (1) is winded up by a wire (4) with at least two threads (2), the threads (2) are on the core (1) placed tightly next to each other and the effective width (w)of one thread (2) corresponds to the radius of the core (1) in the circular core (1) cross-section, or corresponds to the equivalent radius in other shapes of the core (1) with deviation up to +-75%. The wire (4) of the coil is flat, or the coil includes several wires held parallel to each other (41 to 4N) forming a multi-stage thread. The emitter can be placed in the removable memory card (5) and/or on the PCB board (10) and/or SIM card (9) and/or battery (11). Modulation of data transmitted by the emitter uses electromagnetic wave generator with a frequency different from the receiver, difference of these frequencies corresponds to the subcarrier frequency.