Transparent Electromagnetic Wave Absorbing Device Using Periodic Unit Cells
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Solution Overview
Problem
Conventional electromagnetic wave absorbers are difficult to manufacture and adjust for absorption frequency band and characteristics, and they are not transparent, limiting their use in applications where light transmission is required.
Innovation Solution
An electromagnetic wave absorbing device using a periodic structure with a transparent resistive material, including a metal conductor layer, a dielectric layer made of glass, and a unit cell pattern layer with resistive material, allowing for adjustable absorption frequency and transparency, enabling the device to be integrated into existing transparent structures like windowpanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electromagnetic wave absorbers are used, then absorption characteristics can be achieved, but manufacturing process is complicated and absorption frequency band adjustment is difficult
Solution Approach 1:
The patent applies parameter changes by modifying the geometric dimensions of the unit cell patterns (width, length, spacing) and the properties of the dielectric layer (thickness, permittivity) to adjust the absorption frequency band. This allows continuous tuning of absorption characteristics without changing the fundamental structure, making both manufacturing and frequency adjustment straightforward.
Solution Approach 2:
The patent segments the absorber into a periodic array of identical unit cell patterns on a dielectric substrate. This segmentation allows the complex absorption function to be achieved through simple, repetitive geometric structures that are easy to manufacture using standard PCB or lithography techniques, while still providing effective electromagnetic wave absorption.
2Reliability
If conventional electromagnetic wave absorbers are used, then absorption function is provided, but transparency is not achieved, limiting application in windowpanes
Solution Approach 1:
The patent applies local quality by making the unit cell patterns and ground plane transparent or semi-transparent in the visible spectrum while maintaining their electromagnetic wave absorption function. The dielectric layer is selected to be transparent, and the conductive elements use transparent conductive oxides or fine mesh structures, allowing light transmission while providing absorption in specific frequency bands.
Solution Approach 2:
The patent uses composite materials combining transparent dielectric substrates with transparent or semi-transparent conductive elements. This composite structure achieves both optical transparency and electromagnetic wave absorption functionality, enabling application in windowpanes and other transparent surfaces.
3Reliability
If Salisbury screen structure is used, then absorption performance can be adjusted, but dielectric spacer thickness must be more than λ/4
Solution Approach 1:
The patent uses resonant oscillation of electromagnetic currents within the unit cell patterns at specific frequencies to achieve absorption. The resonant frequency is determined by the geometric dimensions of the unit cells and the dielectric layer thickness, allowing thin-film designs that are much thinner than the λ/4 requirement of Salisbury screens while maintaining effective absorption through resonance enhancement.
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 device effectively absorbs electromagnetic waves of specific frequency bands while maintaining transparency, providing a cost-effective and versatile solution for reducing electromagnetic interference in various environments, including homes and hospitals, without the need for new windowpanes.
Implementation Method 1
a unit cell pattern layer which is formed on the dielectric layer and in which at least two unit cell patterns made of a resistive material are periodically arranged
Implementation Method 2
An electromagnetic bandgap (EBG) as a technique of employing a periodic structure may be implemented by periodically arranging specifically designed unit cell patterns on a typical electric conductor at regular intervals
Data Source
AI summary
An electromagnetic wave absorbing device includes a ground layer formed of a metal conductor layer, a dielectric layer formed on the ground layer, and a unit cell pattern layer which is formed on the dielectric layer and made of resistive materials, wherein at least two electromagnetic bandgap-based unit cell patterns are periodically arranged on the unit cell pattern layer.