NFC Antenna FPCB Integrated Capacitor Design
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Solution Overview
Problem
Existing NFC antennas face challenges in being lightweight, thin, short, and small while maintaining a high quality factor at a low cost, particularly in mobile devices, due to the complexity and cost associated with the double resonance loop structure.
Innovation Solution
A double resonance loop antenna design is implemented using a flexible printed circuit board (FPCB) with a source coil and resonance coil pattern, where the resonance capacitor is formed with a conductive line pattern, eliminating the need for chip capacitors and additional ports, thereby reducing costs and enhancing quality factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double resonance loop structure is used to raise magnetic field, then the quality factor is improved, but the device complexity and cost increase due to requiring four ports and two chip capacitors
Solution Approach 1:
The patent combines the resonance capacitor function with the existing conductive line patterns on the FPCB. The capacitor pattern is integrated into the circuit board's conductive layers, merging the capacitor functionality with the structural elements already present in the antenna design, thereby eliminating the need for separate chip capacitors
Solution Approach 2:
The conductive lines on the FPCB serve multiple functions: they form the antenna loops, provide electrical connections, and create the resonance capacitor. This multi-functional design allows the same structural elements to fulfill multiple roles, reducing the need for additional components like separate chip capacitors and extra ports
2Reliability
If a double resonance loop structure is used to raise magnetic field, then the quality factor is improved, but the manufacturing cost increases due to additional chip capacitors and ports
Solution Approach 1:
The resonance capacitor is merged with the FPCB's conductive line patterns. By forming the capacitor using the same manufacturing processes and materials as the antenna traces (copper conductors on the flexible circuit board), the design eliminates the need for separate chip capacitor components, reducing both component count and assembly complexity
Solution Approach 2:
The capacitor is implemented as a pattern copy of the existing conductive line structure. The capacitor pattern uses the same conductive material and fabrication techniques as the antenna traces, simply arranged in a configuration that provides capacitive coupling rather than inductive coupling, thereby using proven manufacturing processes without additional cost
3Reliability
If traditional NFC antenna structure is used, then the quality factor can be maintained, but the device cannot be made light, thin, short, and small due to additional external space requirements
Solution Approach 1:
The patent transitions from a three-dimensional assembly with separate chip capacitors mounted on the antenna structure to a two-dimensional planar design where all elements (antenna loops and capacitor) are integrated into the FPCB's conductive layers. This dimensional reduction allows the antenna to be flatter and more compact
Solution Approach 2:
The capacitor pattern is nested within the antenna structure on the same FPCB substrate. The conductive lines forming the capacitor are positioned in the spaces between or alongside the antenna loops, effectively nesting the capacitor function within the existing antenna footprint rather than requiring additional external space
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 design achieves a high quality factor and cost-effectiveness by minimizing the use of chip capacitors and additional ports, allowing for a compact and efficient NFC antenna in mobile devices.
Implementation Method 1
The NFC antenna with a loop antenna connects a chip capacitor to a single loop antenna to generate LC resonance
Implementation Method 2
Near field communication (NFC) is a contactless near field communication technique using a frequency bandwidth of 13.56 MHz
Implementation Method 3
one terminal of the capacitor pattern is connected to a first terminal of the second conductive line and the other terminal of the capacitor pattern is connected to a second terminal of the second conductive line
Data Source
AI summary
An antenna of a near field wireless communication device is provided. The antenna may include: a source coil pattern formed on one surface of a flexible printed circuit board (FPCB) and formed with a first conductive line between a first antenna port and a second antenna port; a resonance coil pattern formed with a second conductive line, which electrically separates from the source coil pattern; and a capacitor pattern electrically connected to the second conductive line, wherein one terminal of the capacitor pattern is connected to a first terminal of the second conductive line and the other terminal of the capacitor pattern is connected to a second terminal of the second conductive line through a third conductive line formed on the other surface of the FPCB.