Network Antenna Transition Zone for Low Radar Reflection

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Solution Overview

Problem

Existing methods for integrating array antennas into environments suffer from edge diffraction and surface wave reflections, leading to increased radar cross-sectional area and degraded radiation performance, with current solutions being insufficient in addressing structural transitions and environmental compatibility.

Innovation Solution

A method that optimizes the transition between the antenna and its environment by varying the reflectivity of radiating elements along a calculated path in the complex plane, minimizing diffraction effects by adjusting parameters such as pitch, geometric dimensions, or material properties to match the antenna and medium reflectivities, thereby reducing the radar equivalent surface and enhancing radiation characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the antenna is integrated directly into the medium, then the installation is simple, but edge diffraction occurs and radar cross-sectional area increases

Engineering Contradiction:
Improveinstallation simplicityVSAvoidedge diffraction and radar cross-sectional area
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a transition zone composed of radiating elements as an intermediary structure between the antenna and the medium. This transition zone acts as a mediator that gradually transforms the electromagnetic characteristics from the antenna side to the medium side, avoiding abrupt discontinuities that cause edge diffraction. The radiating elements in the transition zone are configured with varying parameters to create a smooth electromagnetic transition, thereby reducing the radar cross-sectional area while maintaining integration simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by varying the reflectivity, pitch, geometric dimensions, or material properties of the radiating elements along the transition zone. These parameter variations create a gradual electromagnetic transition from the antenna interface (with reflectivity close to Γa) to the medium interface (with reflectivity close to Γm). This continuous parameter change eliminates sharp discontinuities, reducing edge diffraction effects and parasitic reflections while maintaining structural simplicity.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If absorbent materials are added to the environment close to the antenna, then cavity reflections are reduced, but an abrupt discontinuity between the medium and antenna remains

Engineering Contradiction:
Improvecavity reflectionsVSAvoidelectromagnetic discontinuity
Core Design Contradiction:
Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

Instead of using absorbent materials that create abrupt discontinuities, the patent employs a transition zone where the reflectivity parameter changes gradually from the antenna reflectivity (Γa) to the medium reflectivity (Γm). The radiating elements in the transition zone are configured with progressively varying parameters, creating a smooth electromagnetic transition that reduces cavity reflections without introducing sharp discontinuities. This approach maintains electromagnetic field continuity while attenuating parasitic reflections.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If additional dummy radiating elements with dedicated loads are added, then surface wave diffraction is reduced, but the structural transition problem persists

Engineering Contradiction:
Improvesurface wave diffractionVSAvoidstructural transition
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the transition zone radiating elements with the existing antenna structure, using the same radiating element technology throughout. Instead of adding separate dummy elements with dedicated loads, the transition zone employs radiating elements with varying parameters (reflectivity, pitch, dimensions, or material properties) that are integrated into the existing antenna architecture. This unified approach reduces surface wave diffraction while avoiding additional structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

4Object-affected harmful factors

If resistive materials are used to treat the aperture, then surface waves are gradually attenuated, but the method is limited to antennas with dielectric layers

Engineering Contradiction:
Improvesurface wave attenuationVSAvoidapplicability to different antenna types
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent uses parameter changes in the radiating elements themselves (reflectivity, pitch, geometric dimensions, or material properties) rather than relying on resistive coatings on dielectric layers. This approach is universally applicable to various antenna types including metallic waveguide antennas, patch antennas, and other configurations regardless of their substrate material. The transition zone radiating elements can be configured with varying parameters to achieve gradual surface wave attenuation and diffraction reduction for any antenna type.

Inventive Principle:
Principle #35Parameter changes

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 approach significantly reduces diffraction effects and radar cross-sectional area, improving radiation performance and efficiency, with substantial attenuation of parasitic effects achieved across various frequencies and polarizations.

Implementation Method 1

Integrating the antenna onto a carrier creates a sharp electrical discontinuity that results in edge diffraction. This diffraction phenomenon disrupts the antenna's radiation.

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

The incident wave I then generates a specular wave S but also a parasitic retroreflected wave SER linked to the discontinuity B.

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

One solution consists of adding materials that absorb electromagnetic waves to the environment close to the antenna. The presence of absorbers eliminates this phenomenon of surface wave reflection at the edges of the antenna.

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP3903381B1Method for integrating a "network" antenna into a different electromagnetic medium, and associated antenna
Publication Date: 2024.02.07 THALES SA
  • EP3903381B1 patent drawingFigure 1~3
  • EP3903381B1 patent drawingFigure 4~6
  • EP3903381B1 patent drawingFigure 7~8

AI summary

The invention relates to a method for integrating a network antenna (A) into a medium (M), the antenna comprising a plurality of radiating elements (ERT) that ensure the transition between the antenna and the medium, the reflectivity of each element depending on a parameter, the reflectivity of a first element being close to that of the medium, the reflectivity of a last element being close to that of the antenna, and the reflectivity parameter of the elements varying from one element to the next. The method according to the invention comprises the following steps: - Step 1: computing a path equal to the sum of the variations in reflectivity from one element to the next element; - Step 2: optimising the variation in the reflectivity parameter such that the radar cross-section of the antenna is as low as possible or such that the antenna best fulfils the radiation objectives; - Step 3: determining the different elements according to the parameter; - Step 4: simulating the overall reflectivity and/or radiation of the antenna.