Stacked PCB Coupler Using Ground-Layer Holes for RF Coupling
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Solution Overview
Problem
Conventional couplers in MIMO antenna arrays face issues such as waste of PCB space due to planar structure, deterioration of RF performance due to via design, and fixed output characteristics.
Innovation Solution
A coupler design with two coupling lines located on different substrate layers, sandwiched by a ground layer with hole groups that allow electromagnetic coupling, reducing PCB space and improving RF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional planar coupler structure is used, then the coupling function is achieved, but PCB space is wasted
Solution Approach 1:
The patent transitions from a conventional planar (2D) coupler structure to a three-dimensional stacked structure where coupling lines are arranged vertically across multiple layers. The first coupling line is positioned on an upper surface while the second coupling line is positioned on a lower surface, with hole groups penetrating through the substrate to enable electromagnetic coupling between layers. This dimensional change reduces the horizontal PCB footprint while maintaining coupling functionality.
2Reliability
If metal vias are used for coupling, then the coupling function is achieved, but RF performance deteriorates
Solution Approach 1:
The patent removes metal vias from the coupling mechanism and replaces them with hole groups that are filled with dielectric material or left as air cavities. The electromagnetic coupling is achieved through the geometric configuration of these hole groups rather than through conductive via paths, eliminating the harmful effects of metal vias on RF performance such as signal loss, impedance discontinuity, and parasitic effects.
Solution Approach 2:
The patent changes the coupling mechanism from conductive (metal via-based) to dielectric/geometric (hole group-based). By modifying the physical and electromagnetic parameters of the coupling structure - using non-conductive hole groups with specific geometric arrangements instead of metal vias - the RF performance is improved while maintaining the coupling function.
3Adaptability or versatility
If a conventional coupler design is used, then the basic coupling function is provided, but output characteristics are fixed
Solution Approach 1:
The patent introduces adjustability to the coupler design by making the hole groups geometrically configurable. The position, size, shape, and distribution of the hole groups can be modified to dynamically adjust coupling strength, phase difference, and output characteristics. This enables the coupler to be adapted for different applications and performance requirements while maintaining a relatively simple overall structure.
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
Saves PCB space, enhances RF performance, and reduces costs by eliminating the need for metal vias while allowing flexible output characteristics.
Implementation Method 1
a plurality of hole groups being formed in the first ground layer and being geometrically designed such that an electro-magnetic field of the first coupling line is coupled to the second coupling line through the plurality of hole groups
Data Source
AI summary
Embodiments of the present disclosure relate to a coupler, antenna module and electronic device. The coupler comprises a first substrate layer and a second substrate layer located below the first substrate layer. The coupler also comprises a first coupling line located on an upper surface of the first substrate layer and a second coupling line located on a lower surface of the second substrate layer. The coupler further comprises a first ground layer located between a lower surface of the first substrate layer and an upper surface of the second substrate layer, a plurality of hole groups being formed in the first ground layer and being geometrically designed such that an electromagnetic field of the first coupling line is coupled to the second coupling line through the plurality of hole groups. In this way, PCB space and size may be saved, RF performance may be improved, and PCB cost may be reduced.