Layered Radio Wave Absorber for Thin Millimeter-Wave Radar Integration
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Solution Overview
Problem
The installation of a millimeter-wave radar inside a vehicle bumper causes undesirable reflections that interfere with direct waves and degrade target detection performance due to insufficient absorption by conventional radio wave absorbers, which often require excessive thickness for effective loss.
Innovation Solution
A radio wave absorber is designed with two stacked layers having different dielectric constants, where the first layer's thickness and second layer's dielectric constant are set to create a phase difference, allowing the first and second reflected waves to cancel each other, enhancing absorption without increasing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional radio wave absorbers are used, then radio wave absorption is achieved, but the absorber thickness becomes excessive
Solution Approach 1:
The radio wave absorber is divided into multiple layers (first layer, second layer, and third layer) with different dielectric constants. Each layer contributes differently to the overall absorption mechanism, allowing the system to achieve effective absorption with reduced total thickness compared to conventional single-layer absorbers.
Solution Approach 2:
The patent utilizes changes in dielectric constant across different layers to achieve phase difference and wave cancellation. By carefully selecting materials with specific dielectric constants and controlling layer thicknesses, the system creates constructive and destructive interference patterns that enhance absorption while reducing the required thickness.
2Length of stationary object
If absorber thickness is reduced, then installation space is saved, but absorption effectiveness deteriorates
Solution Approach 1:
The patent employs a composite structure with multiple layers of materials having different dielectric constants. This composite approach allows each layer to contribute differently to the absorption mechanism, achieving high absorption effectiveness in a thinner overall structure than would be possible with a single homogeneous material.
Solution Approach 2:
Different regions (layers) of the absorber are assigned different dielectric properties optimized for their specific function. The first layer, second layer, and third layer each have tailored dielectric constants that optimize the local electromagnetic field interaction, contributing to overall absorption efficiency in a compact configuration.
3Ease of manufacture
If single-layer absorber structure is used, then manufacturing is simple, but absorption performance is insufficient
Solution Approach 1:
The absorber is segmented into multiple manufacturable layers that can be produced and assembled using standard manufacturing processes. While the structure is more complex than a single layer, each layer can be manufactured independently using conventional techniques, maintaining ease of manufacture while achieving superior absorption performance.
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
This configuration improves absorption efficiency by canceling reflected waves, reduces the required thickness of the second layer, and enhances robustness against structural tolerances, thereby maintaining performance consistency.
Implementation Method 1
the thickness of the first layer is set, such that the first reflected wave and the second reflected wave have a phase difference
Implementation Method 2
the first reflected wave and the second reflected wave at least partially cancel each other
Implementation Method 3
The first layer and the second layer respectively have dielectric constants that are different from each other
Data Source
AI summary
A first layer and a second layer are stacked one another and respectively have different dielectric constants. The dielectric constants are set, such that a first reflected wave and a second reflected wave have a same intensity. A thickness of the first layer is set, such that the first reflected wave and the second reflected wave have a phase difference to at least partially cancel each other. The first reflected wave is reflected on an exposed surface of the first layer when a target radio wave is incident on the exposed surface. The second reflected wave is a reflected wave that is incident from the exposed surface, reflected on a boundary surface between the first layer and the second layer, and emitted from the exposed surface. The exposed surface is on an opposite side of the boundary surface.