Metasurface Multi-Layer Waveguide for Low-Leakage PCB Fabrication
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Solution Overview
Problem
Existing waveguide technologies face challenges in achieving compactness, low loss, and reduced leakage while maintaining cost-effectiveness, particularly in high-frequency applications, and current manufacturing methods like CNC-milling and molding are costly and imprecise.
Innovation Solution
A multi-layer waveguide with electromagnetic metasurfaces featuring unconnected thin layers and textured surfaces, comprising thick and thin sections, creates an electromagnetic band gap to suppress leakage without requiring galvanic contact, allowing for easy and cost-effective production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrate integrated waveguides (SIW) are used to achieve compactness and cost-effectiveness, then production cost is reduced and compactness is improved, but insertion loss increases due to inherent dielectric losses
Solution Approach 1:
The waveguide structure is divided into multiple separate layers (top layer, intermediate layers, bottom layer) that are stacked together. Each layer is processed independently using PCB technology, allowing for easier and more cost-effective manufacturing while maintaining the waveguide functionality through the stacked configuration.
Solution Approach 2:
Metasurfaces are introduced as intermediary structures between the stacked layers to suppress electromagnetic leakage. These metasurfaces consist of periodic patterns (such as pins or ridges) that create electromagnetic bandgaps, preventing wave leakage through the gaps between layers without requiring direct galvanic contact between layers.
2Loss of energy
If hollow waveguides are used to reduce insertion loss, then energy loss is reduced, but leakage increases when layers are separated by gaps
Solution Approach 1:
Metasurfaces serve as intermediary structures placed between the stacked waveguide layers. These metasurfaces contain periodic patterns (pins, ridges, or other geometric structures) that create electromagnetic bandgaps, effectively blocking wave leakage through the gaps between layers while maintaining the low insertion loss characteristics of hollow waveguides.
Solution Approach 2:
The electromagnetic properties of the waveguide structure are modified by introducing metasurfaces with specific geometric parameters (pin height, spacing, pattern geometry) that create stopbands at the operating frequency. This changes the propagation characteristics to prevent leakage while maintaining low loss transmission.
3Object-generated harmful factors
If dielectric waveguides are used to reduce leakage, then leakage is reduced, but production cost increases due to requirements for high conductivity and manufacturing accuracy
Solution Approach 1:
The waveguide is segmented into multiple separately processable layers that can be manufactured using standard PCB techniques. Each layer is processed independently, avoiding the need for high-precision monolithic manufacturing, and then stacked together with gaps between layers that are managed by metasurfaces.
Solution Approach 2:
Metasurfaces are introduced as intermediary structures between the stacked layers to suppress electromagnetic leakage. These metasurfaces consist of periodic patterns (such as pins or ridges) that create electromagnetic bandgaps, preventing wave leakage through the gaps between layers without requiring direct galvanic contact between layers.
4Productivity
If CNC-milling and molding are used for manufacturing waveguides, then production is feasible for frequencies below 60 GHz, but cost and precision deteriorate at higher frequencies (E-band and D-band)
Solution Approach 1:
The waveguide structure is divided into multiple thin layers that can be manufactured using PCB fabrication processes (laser cutting, etching, chemical etching) which provide better precision at high frequencies. Each layer is processed independently at a smaller scale, avoiding the limitations of CNC-milling and molding when features become very small relative to the tool size.
Solution Approach 2:
The manufacturing approach transitions from three-dimensional CNC-milling and molding to a layered two-dimensional PCB fabrication process. Each layer is fabricated separately using planar processing techniques that maintain precision even when feature sizes are very small, then the layers are stacked to form the complete waveguide 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
The solution provides a compact, low-loss waveguide with reduced leakage, suitable for high-frequency applications, and enables efficient manufacturing by eliminating the need for galvanic connections between layers.
Implementation Method 1
The small gap between the layers and the metasurface provide the electromagnetic bandgap (EBG) structure.
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A multi-layer waveguide (1) comprising at least three physical layers (21, 2a, 2b, 2c, ..., 2n, 22) assembled into a multi-layer waveguide (1). The layers are a top layer (21), one or more intermediate layer (2a, 2b, ..., 2n), and a bottom layer (22). The multi-layer waveguide (1) further comprises a waveguide channel (77) being an elongated aperture (7) in at least one intermediate layer (2a, 2b, ..., 2n). At least one layer (21, 2a, 2b, ..., 2n, 22) has a metasurface (3) on a first surface (5a) facing a first adjoining layer, wherein the metasurface (3) surrounds the elongated aperture (7) and comprise thick (3a) and thin (3b) sections.