Dual-Layer Radome Absorber Structure for Low-RCS Radar Integration

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Solution Overview

Problem

Conventional radar devices suffer from high reflectivity and multibounce reflections, leading to angular errors and ghost targets, particularly when integrated behind vehicle fascias, which complicates integration and reduces performance.

Innovation Solution

A dual-layer radome structure comprising a radome layer and an absorber layer with specific permittivity and thickness ranges, positioned to minimize radar wave reflection and interference, with gaps and surface structuring to enhance wave transmission and absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional single-layer radome is used, then the manufacturing process is simple, but the radar cross section remains high and multibounce reflections occur

Engineering Contradiction:

Improveradome manufacturing simplicityVSAvoidradar cross section and multibounce reflections

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The radome is divided into multiple layers with different material properties. The first layer has relative permittivity 2-4 and the second layer has relative permittivity 8-12, creating a segmented structure that reduces radar cross section through controlled impedance transitions and minimizes multibounce reflections by managing wave propagation at each interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The radome uses composite material construction with two distinct layers having different electromagnetic properties. The combination of materials with specific permittivity ranges (first layer: 2-4, second layer: 8-12) creates a composite structure that achieves low radar cross section while maintaining mechanical protection functions.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If radar devices are integrated behind a fascia, then the field of view is widened, but multibounce reflections from the fascia increase angular errors and ghost targets

Engineering Contradiction:

Improvefield of view and integration flexibilityVSAvoidangular accuracy and target detection reliability

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The second layer with higher relative permittivity (8-12) is specifically designed to absorb and dissipate multibounce reflections from the fascia, converting the harmful reflected waves into minimal energy. This layer acts as an electromagnetic absorber that eliminates ghost targets and angular errors while preserving the wide field of view integration benefit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If absorber materials are directly applied onto antenna surfaces, then radar cross section is reduced, but the manufacturing complexity and cost increase significantly

Engineering Contradiction:

Improveradar cross sectionVSAvoidradar surface treatment complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The absorber function is merged with the protective radome structure itself. Instead of applying separate absorber materials onto the antenna, the radome's second layer serves dual purposes: mechanical protection and electromagnetic absorption. This integration eliminates additional manufacturing steps and reduces overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The radome structure is designed to perform multiple functions simultaneously: it provides mechanical protection for the antenna, reduces radar cross section through its layered structure, and minimizes multibounce reflections. This multi-functional design eliminates the need for separate components and simplifies the overall radar assembly.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 dual-layer radome significantly reduces radar cross section, minimizes multibounce reflections, and improves accuracy and reliability of radar systems, especially in automotive applications like collision avoidance and adaptive cruise control.

Implementation Method 1

the second layer has a higher capacity to absorb radar waves than the material of the first layer

Methodology Applied

Scientific EffectRadar wave absorption: Absorption (EM radiation)

Implementation Method 2

the first layer has a relative permittivity in the range 2 to 4... the second layer has a relative permittivity in the range 8 to 12

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS20250350022A1Performance Optimized Radome Absorber Attachment for Radar RCS Reduction

Publication Date: 2025.11.13 APTIV TECHNOLOGIES AG

AI summary

A radar device includes at least one antenna and a radome. The at least one antenna has a field of view. The radome covers the at least one antenna. The radome includes a first layer and a second layer in form of a layer stack. The layer stack is configured to have a low reflection for radar waves.