Reflectarray Element Spacing for 360-Degree Phase Control

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Solution Overview

Problem

Conventional reflectarrays using mushroom-like structures face challenges in achieving a wide range of reflection phases, particularly around plus and minus 180 degrees, leading to unachievable reflection phases and reduced wave characteristics due to complex multi-layered structures and processing limitations.

Innovation Solution

The design method involves using a single-layer wire configuration for the reflectarray, where the element spacing determines the reflection phase, allowing for simultaneous change in capacitance and inductance values across all elements, eliminating the need for complex multi-layered structures and ensuring consistent gap sizes between patches.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple element structures with different heights, via lengths, or substrate thicknesses are combined to achieve a wide range of reflection phases, then the range of achievable reflection phases is improved, but the device complexity and manufacturing cost increase due to multiple electrically conducting layers

Engineering Contradiction:
Improverange of reflection phasesVSAvoidnumber of electrically conducting layers
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the parameter being adjusted from physical dimensions (patch size, via length, substrate thickness) to element spacing. By varying the spacing between elements in a single-layer structure, the reflection phase can be controlled across a wide range including near 180 degrees, eliminating the need for multiple conducting layers with different heights and thicknesses.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the size of the patch is adjusted to achieve desired reflection phases, then the reflection phase control is improved, but the manufacturing precision becomes difficult to achieve when space between large patches becomes very narrow

Engineering Contradiction:
Improvereflection phase controlVSAvoidgap between patches
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent transitions from controlling reflection phase through patch size adjustment to controlling it through element spacing variation. This parameter change allows for achieving desired reflection phases including near 180 degrees without requiring extremely narrow gaps between patches, thereby avoiding manufacturing precision issues.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If conventional techniques are used to achieve reflection phases near plus or minus 180 degrees, then the reflection phase range is extended, but the characteristic of the reflected wave deteriorates due to unachievable reflection phases

Engineering Contradiction:
Improvereflection phase rangeVSAvoidreflected wave characteristic
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses element spacing as the control parameter to achieve reflection phases near 180 degrees, which were previously unachievable with patch size adjustment. This approach maintains reflected wave characteristics because it avoids the extreme gap conditions that lead to manufacturing errors and performance degradation.

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 simplifies the production of reflectarrays with improved reflection characteristics by covering a 360-degree phase range without the need for multi-layered structures, enhancing the reflection efficiency and reducing manufacturing complexity.

Implementation Method 1

Each of the elements is formed by a structure that reflects the radio wave

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

values of the reflection phases are varied by changing a value of capacitance which is determined by the gap between the elements of the mushroom-like structures

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

values of the reflection phases are varied by changing a value of inductance which is determined by the length of the via

Methodology Applied
Scientific EffectInductance: Inductor

Data Source

PatentEP2822098B1Reflect array, and design method
Publication Date: 2018.04.11 NTT DOCOMO INC
  • EP2822098B1 patent drawingFigure 1
  • EP2822098B1 patent drawingFigure 2
  • EP2822098B1 patent drawingFigure 3

AI summary

A reflectarray reflects an incident wave in a desired direction. The reflectarray includes a substrate including a surface which is perpendicular to a predetermined axis, and elements disposed on the substrate. A specific element among the elements reflects the incident wave with a specific reflection phase among a plurality of reflection phases. Each of the elements has an element structure including, at least, a patch and a ground plate. Element spacing of first neighboring elements is different from element spacing of second neighboring elements, and a length of a gap between patches of the first neighboring elements is equal to a length of a gap between patches of the second neighboring elements.