Aperiodic Metallic Grid for EMI Shielding
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Solution Overview
Problem
Conventional metallic grids used to reduce electromagnetic interference (EMI) often cause signal loss and false positives due to diffractive effects at optical wavelengths, particularly when periodic patterns lead to the formation of side lobes that can misidentify objects.
Innovation Solution
A metallic grid with apertures aligned in a pattern defined by a deterministic relation, where the distances between apertures and an observation point are uncorrelated, reducing diffractive effects while maintaining effective EMI shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a periodic pattern is used in the metallic grid, then EMI shielding is effective, but diffractive side lobes are generated causing false positives
Solution Approach 1:
The patent applies asymmetry by transitioning from a periodic symmetric aperture pattern to an aperiodic asymmetric pattern. The aperiodic pattern lacks the translational symmetry that causes constructive interference and side lobe formation in periodic grids, thereby eliminating false positives while maintaining EMI shielding through continuous metal coverage.
Solution Approach 2:
The patent changes the fundamental parameter of pattern periodicity from periodic to aperiodic. This parameter change disrupts the coherent diffraction pattern that produces side lobes, while the metal density and aperture size parameters are optimized to maintain both EMI shielding effectiveness and optical transmission properties.
2Reliability
If a metallic coating is added to block EMI, then electromagnetic interference is reduced, but optical transmission is reduced causing signal loss
Solution Approach 1:
The patent applies local quality by creating regions of varying metal density and aperture distribution across the grid. The aperiodic pattern allows local optimization where metal provides EMI shielding in certain regions while apertures maintain optical transmission in others, achieving both functions simultaneously rather than uniformly across the entire grid.
Solution Approach 2:
The patent effectively creates a composite structure combining metal regions (for EMI shielding) and aperture regions (for optical transmission). The aperiodic pattern optimizes the spatial distribution and proportion of these two components, achieving a balance between electromagnetic interference protection and optical signal transmission that neither pure metal nor uniform aperture patterns can achieve.
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 effectively reduces diffractive side lobes, allowing for accurate identification of targets while maintaining robust EMI shielding, with even metal density distribution ensuring consistent conductance and optical transmission.
Implementation Method 1
Protecting a circuit from EMI generally involves placing a metallic grid between the circuit and the external source
Implementation Method 2
the patterned metal coating is designed to allow transmission of optical wavelengths through the coating
Implementation Method 3
if the pattern of the grid is periodic, light passing through the grid may generate a diffractive scatter halo having side lobes
Data Source
AI summary
An electromagnetic interference shield is disclosed. The electromagnetic interference shield includes an optically transparent substrate and a metallic coating on the optically transparent substrate. The metal coating is characterized by a plurality of apertures aligned in a pattern that is defined by a deterministic relation. Distances between each of the plurality of apertures and an observation point in an associated image plane are uncorrelated.