Waveguide-PCB RF Interconnection via Galvanic Via Wall
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Solution Overview
Problem
Existing systems for integrating rectangular waveguides with printed circuit boards (PCBs) in high frequency/millimeter wave applications are bulky, heavy, and mechanically incompatible, requiring complex signal transitions that are not compact enough for applications like 5G mmW massive MIMO systems.
Innovation Solution
A compact system comprising a waveguide and PCB, where the PCB has a ground layer, dielectric material layer, and signal layer with a coupling pad and output transmission lines, and a non-conducting slot, with an electric wall connecting the coupling pad to the ground layer, allowing for galvanic contact and eliminating the need for a back short, and through-holes that are metallized to form part of the electric wall for secure fixing and contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional waveguide-PCB integration methods are used, then signal transmission is achieved, but the system becomes bulky and heavy
Solution Approach 1:
The patent transitions from planar 2D PCB traces to 3D vertically stacked transmission paths. The waveguide opens downward onto the PCB bottom side, with via holes providing vertical galvanic connections through the PCB thickness, enabling compact Z-axis integration instead of lateral expansion
Solution Approach 2:
The waveguide opening is positioned to overlap with the PCB ground layer opening, and the via holes are nested within the PCB thickness. This nesting allows the waveguide to be directly coupled to the PCB without lateral spacing, minimizing overall system volume while maintaining signal integrity
2Volume of moving object
If waveguide and PCB are mechanically integrated, then compactness is achieved, but mechanical compatibility and secure fixation become difficult
Solution Approach 1:
The via holes serve dual functions: they provide galvanic electrical connections for signal transmission and simultaneously act as mechanical receptacles for screws or pins. This self-service design integrates electrical and mechanical functions into a single feature, simplifying assembly while achieving compact integration
Solution Approach 2:
The via holes are designed to perform multiple functions simultaneously: electrical galvanic connection, mechanical fixation point, and alignment reference. This multi-functionality reduces the number of separate components needed, easing manufacturing and assembly while maintaining compactness
3Volume of moving object
If compact transition structure is used, then integration density is improved, but signal reflection and power loss increase
Solution Approach 1:
The patent optimizes the via hole diameter, spacing, and depth to control impedance transformation. By carefully selecting via dimensions and their arrangement around the coupling pad, the transition impedance is matched to minimize reflections while maintaining compact size. The ground layer opening dimensions are also optimized for impedance control
4Volume of moving object
If galvanic connection without back short is implemented, then compactness is achieved, but electrical contact reliability may be compromised
Solution Approach 1:
The patent replaces the traditional mechanical back short structure with an electrical galvanic connection achieved through metallized via holes. The via holes provide direct conductive paths from the waveguide opening through the PCB to the ground layer, eliminating the need for separate mechanical shorting structures while ensuring reliable electrical contact
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
Enables a compact, high-integration system that functions as a power divider/balun, providing tight mechanical fixation and good galvanic contact without affecting operation, reducing manufacturing costs, and allowing for efficient power transfer with minimal signal reflection.
Implementation Method 1
an electric wall galvanically connecting the coupling pad through the dielectric layer to the ground layer
Implementation Method 2
rectangular waveguides are frequently used in high frequency/millimeter wave (mmW) applications to transmit or filter mmW signals
Data Source
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AI summary
According to one aspect the present invention refers to a system comprising a waveguide having a body with a first end having an opening, and a printed circuit board, PCB, having a bottom side and a opposed top side, wherein the PCB comprises a ground layer, a dielectric material layer and a signal layer arranged in a layer stack from the bottom side to the top side of the PCB, wherein the dielectric material layer is arranged between the ground layer and the signal layer, wherein the signal layer comprises a coupling pad and a first and a second output transmission line both connected to the coupling pad, further comprising a non-conducting slot in the ground layer, further comprising a electric wall galvanically connecting the coupling pad through the dielectric material layer to the ground layer, wherein the first end of the waveguide is arranged on the bottom side and is galvanically connected with the ground layer, wherein the opening, the non-conducting slot and the coupling pad are aligned such that in a stacking direction of the layer stack the opening, the non-conducting slot and the coupling pad at least partially overlap. In a second aspect the present invention is directed to a printed circuit board, PCB, having a bottom side and a opposed top side, wherein the PCB comprises a ground layer, a dielectric material layer and a signal layer arranged in a layer stack from the bottom side to the top side of the PCB, wherein the dielectric material layer is arranged between the ground layer and the signal layer, wherein the signal layer comprises a coupling pad and a first and a second output transmission line both connected to the coupling pad, further comprising a non-conducting slot in the ground layer, further comprising a electric wall galvanically connecting the coupling pad through the dielectric material layer to the ground layer, wherein the non-conducting slot and the coupling pad are aligned such that in a stacking direction of the layer stack the non-conducting slot and the coupling pad at least partially overlap.