Flexible PCB Pattern Antenna With Fill-Cut Ground for RF Matching
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Solution Overview
Problem
Flexible printed circuit boards (PCBs) face difficulties in matching frequency bands for antennas in battery management systems with wireless communication functions, as the thin dielectric layers make it challenging to secure sufficient thickness for antenna components, leading to issues with transmission output and reception sensitivity.
Innovation Solution
A printed circuit board design featuring a pattern antenna on one surface with a first trace connecting to a radio frequency integrated circuit, a fill-cut pattern on the opposing surface to cover the trace, and an impedance-matching circuit to adjust the frequency band, along with a second trace and a second ground pattern for signal transfer, and via holes for impedance matching, which allows for precise frequency matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a flexible printed circuit board is used to mount antenna components, then the PCB can be made thin and flexible, but it becomes difficult to secure sufficient dielectric layer thickness for proper antenna operation and frequency band matching
Solution Approach 1:
The patent transitions from using discrete antenna components (SMD/chip form) to a planar pattern antenna design that utilizes the PCB surface itself as the antenna structure. This dimensional change allows the antenna to function properly on thin flexible PCBs without requiring thick dielectric layers, as the antenna pattern is formed directly on the PCB surface using conductive traces.
Solution Approach 2:
The patent modifies the electrical parameters of the PCB by creating a fill-cut pattern that removes portions of the ground layer. This changes the impedance characteristics and electromagnetic field distribution, enabling proper frequency band matching and antenna performance on thin flexible PCBs where traditional ground patterns would not provide sufficient isolation or impedance control.
2Ease of manufacture
If discrete antenna components (chip or SMD) are mounted on the flexible PCB, then the antenna can be implemented, but frequency-band matching becomes difficult or impossible
Solution Approach 1:
The patent merges the antenna function with the PCB structure itself by forming a pattern antenna using conductive traces on the PCB surface. This integration eliminates the need for separate discrete antenna components while achieving both ease of manufacture (as the antenna is formed during PCB fabrication) and precise frequency-band matching (through the fill-cut ground pattern design).
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A printed circuit board (30) of the present disclosure includes a first surface (31a), a second surface (31b) that is parallel to the first surface (31a), a pattern antenna (27) formed on the first surface (31a), a first trace (312a) for transferring a signal between a radio frequency integrated circuit on the first surface (31a) and the pattern antenna (27), and a fill-cut pattern (322) on the second surface (31b) and covering the first trace (312a), wherein the fill-cut pattern (322) is formed by removing a portion of a first ground pattern (321) in a line shape corresponding to the first trace (312a).