Flexible PCB 5G Antenna Design for Mobile Terminals
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Solution Overview
Problem
The challenge is to reduce the size of 5G antennas while maintaining coverage and preventing parasitic resonance in mobile terminals, where the integration of 5G antennas with integrated circuits is limited by the size of the circuit board and the addition of new electronic elements constrains space.
Innovation Solution
A flexible printed circuit board is used with a structure that includes a first region for the 5G antenna, a second region bent at the side portion with microstrip lines for signal transmission, and a third region with a copper clad laminate antenna emitting signals perpendicular to the first antenna, allowing for reduced board thickness and expanded coverage, and incorporating vias and shielding to mitigate parasitic resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flexible printed circuit board is bent to fit inside the mobile terminal, then the board thickness is reduced and internal space is utilized, but the via structure cannot be maintained causing parasitic resonance
Solution Approach 1:
The flexible printed circuit board is divided into three distinct regions: a first region with a first antenna, a second bent region with microstrip lines, and a third region with a second antenna. This segmentation allows each region to have optimized characteristics - the bent second region fits internal space while the first and third regions maintain proper via structures for signal transmission, preventing parasitic resonance.
Solution Approach 2:
The patent transitions from a conventional planar circuit board layout to a three-dimensional folded structure. The second region is bent at a side portion, creating a spatial configuration that utilizes internal volume of the mobile terminal. This dimensional change allows the board to fit within the terminal while maintaining functional integrity through proper via placement in non-bent regions.
2Area of stationary object
If the circuit board region is reduced to accommodate more electronic elements, then mobile terminal slimness is achieved, but the area available for 5G antenna coverage is limited
Solution Approach 1:
The antenna system extends beyond the planar circuit board area by utilizing the bent second region to position the third region with the second antenna in a different spatial plane. This three-dimensional configuration allows the antenna system to achieve broader coverage without increasing the footprint of the circuit board on the main board, accommodating terminal slimness requirements.
Solution Approach 2:
The antenna functionality is segmented into two separate antennas on different regions of the flexible circuit board. The first antenna is mounted on the first region while the second antenna is formed on the third region, allowing distributed coverage that compensates for the reduced overall circuit board area.
3Adaptability or versatility
If multiple AIPs are added to increase 5G antenna coverage, then coverage is improved, but the circuit board region required increases
Solution Approach 1:
The patent merges the antenna functions into a single integrated flexible printed circuit board structure rather than using separate AIPs. The first and second antennas are both mounted on the same flexible board, which can be folded to achieve spatial separation while maintaining electrical connections. This unified structure provides multi-directional coverage equivalent to multiple AIPs while occupying less circuit board area.
Solution Approach 2:
Instead of placing multiple AIPs in the planar domain which increases board area, the patent uses a bent flexible board configuration that exploits the third dimension. The second region bending allows the third region with the second antenna to be positioned in a different spatial plane, achieving expanded coverage volume without proportionally increasing the circuit board footprint.
Data Source
AI summary
A mobile terminal includes a case; a circuit board disposed inside the case; a flexible printed circuit board electrically connected to the circuit board, and having insulating layers and conductive layers stacked in an alternating manner; a first antenna disposed on a first region of the flexible printed circuit board and facing an end surface of the case and configured to transmit radio signals in a direction toward the end surface of the case; a plurality of microstrip lines disposed on a bent second region of the flexible printed circuit board at a side portion of the first region; and a copper clad laminate stacked second antenna disposed on a third region of the flexible printed circuit board positioned on another side portion of the second region and configured to transmit radio signals in a direction toward a side surface of the case.