Radome Coating Layout for Radar Transmission and Visual Shielding

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Solution Overview

Problem

Conventional radome designs for automotive radar systems compromise both the aesthetic appearance and the functional integrity of radar antennas, as metallic finishes required for appearance attenuate radar signals and negatively influence antenna performance.

Innovation Solution

A frequency selective surface bandpass filter coating on a transmissive substrate, which is reflective for visible light and transmissive for radar frequencies, allowing unobstructed transmission of radar signals while providing a decorative appearance by using a patterned metallic coating that acts as a bandpass filter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Shape

If metallic finishes or metallic graphics are applied to the radome for aesthetic appearance, then the outer appearance is improved, but the radar signal transmission is attenuated and antenna function is compromised

Engineering Contradiction:
Improveaesthetic appearanceVSAvoidradar signal transmission
Core Design Contradiction:
ShapeVSReliability

Solution Approach 1:

The radome surface is segmented into multiple frequency selective surface elements (patches, dipoles, or other resonant structures) that are distributed across the surface. Each element is designed with specific dimensions and spacing to create frequency-selective behavior, allowing the surface to appear metallic visually while maintaining radar signal transmission through controlled electromagnetic resonance properties.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The electromagnetic properties of the radome surface are changed by designing the frequency selective surface elements with specific geometric parameters (size, shape, spacing, orientation) that create resonance at radar frequencies. This allows the surface to be reflective at visible frequencies (aesthetic appearance) while being transmissive at radar frequencies (signal transmission), effectively changing the frequency-dependent parameters of the surface.

Inventive Principle:
Principle #35Parameter changes

2Illumination intensity

If conventional metallic coatings are used to provide decorative appearance, then the visual effect is improved, but the radar antenna performance is negatively influenced

Engineering Contradiction:
Improvevisual reflectivityVSAvoidantenna performance
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

Different regions of the radome surface are designed with locally optimized frequency selective surface elements. The local geometry, size, and arrangement of each element are tailored to achieve the desired visual appearance in that specific area while maintaining radar signal transmission. This allows different parts of the radome to have varying aesthetic properties without compromising overall radar performance.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The radome surface combines multiple materials and structures: a base substrate material providing mechanical strength and optical clarity, and frequency selective surface elements (metallic or conductive) deposited or attached to create the decorative appearance. This composite structure allows the visual properties of metallic materials while maintaining the electromagnetic transmission properties needed for radar operation.

Inventive Principle:
Principle #40Composite materials

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 ensures the radar antenna functions without interference while offering an aesthetically pleasing appearance by using a patterned metallic coating that reflects visible light and transmits radar frequencies, maintaining the radar's performance and appearance without negative influence.

Implementation Method 1

the first coating being transmissive for electromagnetic radiation of at least the first frequency band and being reflective for electromagnetic radiation falling onto the second surface and having a frequency within at least one second frequency band

Methodology Applied
Scientific EffectFrequency selective surface filtering: Filter (optical)

Implementation Method 2

the first coating is configured to act as a frequency selective surface bandpass filter trimmed such that electromagnetic radiation of the first frequency band is transmitted, whereas radiation in the second frequency band is reflected

Methodology Applied
Scientific EffectElectromagnetic radiation transmission and reflection: Reflection

Data Source

PatentEP3909096B1Electromagnetic interference protection for radomes
Publication Date: 2024.01.03 MOTHERSON INNOVATIONS CO LTD
  • EP3909096B1 patent drawingFigure 1~2
  • EP3909096B1 patent drawingFigure 3a~3d
  • EP3909096B1 patent drawingFigure 3e~4

AI summary

The invention relates to a cover (1, 101, 301) for at least one antenna (11, 111) emitting and/or sensing electromagnetic radiation in at least one first frequency band, the cover (1, 101, 301) comprising at least one first surface facing the antenna (11, 111) and at least one second surface averted to the antenna (11, 111), wherein the cover (1, 101, 301) comprises at least one substrate (3, 103) being transmissible for electromagnetic radiation and at least one first coating (7, 107) covering the substrate (3, 103) in at least one first area (19, 119), the first coating (7, 107) being transmissible for electromagnetic radiation of at least the first frequency band, whereas the first coating (7, 107) is reflective for electromagnetic radiation falling onto the second surface and having a frequency within at least one second frequency band.