Aperture-Coupled Microstrip Antenna for Circular Polarization

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Solution Overview

Problem

Current antennas lack optimal combinations of high gain, circular polarization, large effective area, small footprint, multiband capability, low production cost, and lightweight design, which are essential for efficient wireless energy harvesting and transmission.

Innovation Solution

The design incorporates a feedline, ground plane with slots, and a circular radiator, with specific geometric configurations and parameters to achieve circular polarization and dual-band transmission/reception capability, while maintaining a compact size and low cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional microstrip antenna design is used, then the structure is simple and easy to manufacture, but the antenna cannot achieve both high gain and circular polarization with large effective area

Engineering Contradiction:
Improveantenna performanceVSAvoidantenna structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The antenna is divided into distinct functional segments: a feedline layer, a ground plane layer with slots, and a radiator layer. Each segment serves a specific function - the feedline provides signal input, the ground plane with slots enables aperture coupling and circular polarization, and the radiator generates the electromagnetic radiation. This segmentation allows optimization of each component independently while achieving overall high performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The antenna transitions from a conventional planar single-layer design to a multi-layer three-dimensional structure. By stacking the feedline, ground plane, and radiator on separate layers with vertical spacing, the design achieves aperture coupling through the ground plane slots, enabling circular polarization and high gain while maintaining a compact footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the antenna effective area is increased to improve wireless energy transmission, then the gain and energy reception capability improve, but the footprint and device size increase

Engineering Contradiction:
Improveenergy transmission efficiencyVSAvoidantenna footprint
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The antenna achieves large effective area without proportionally increasing footprint by utilizing the vertical dimension. The multi-layer configuration with spaced feedline, ground plane, and radiator creates an effective aperture volume that extends in the z-direction, allowing high gain and energy efficiency within a compact planar footprint.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The antenna employs a composite multi-layer structure combining conductive materials for the feedline and radiator with dielectric substrate materials. This composite construction enables efficient electromagnetic coupling and energy transfer while maintaining structural integrity and compact dimensions.

Inventive Principle:
Principle #40Composite materials

3Adaptability or versatility

If circular polarization is implemented for orientation-independent reception, then the reception capability improves, but the antenna design complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvereception capabilityVSAvoidmanufacturing simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The ground plane contains asymmetric slot configurations that are critical for generating circular polarization. The slots are positioned and dimensioned to create specific current distributions that produce equal-amplitude orthogonal components with 90-degree phase difference, achieving circular polarization through geometric asymmetry rather than complex feed networks.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The ground plane with slots acts as an intermediary element between the feedline and the radiator. It couples energy from the feedline to the radiator while enabling circular polarization through aperture coupling, simplifying the overall design compared to direct feeding methods that would require complex polarization control.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If aperture coupling through ground plane slots is used to achieve circular polarization, then the return loss and polarization purity improve, but the design and manufacturing precision requirements increase

Engineering Contradiction:
Improvereturn lossVSAvoidslot configuration precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The design optimizes specific parameters of the ground plane slots including their dimensions, positions, and orientations to achieve desired performance. By carefully controlling these geometric parameters, the antenna achieves good return loss and circular polarization purity while maintaining manufacturability through standard fabrication tolerances.

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

The antenna achieves efficient energy transmission and reception across multiple frequency bands with improved circular polarization and return loss, meeting performance criteria for S11 parameters, thus enhancing wireless energy harvesting and communication capabilities.

Implementation Method 1

aperture coupled to a feed line

Methodology Applied
Scientific EffectElectromagnetic coupling: Electromagnetic Induction

Implementation Method 2

circular radiator, with specific geometric configurations and parameters to achieve circular polarization

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentEP3329549B1Microstrip patch antenna aperture coupled to a feed line, with circular polarization
Publication Date: 2020.07.01 FREEVOLT TECH LTD
  • EP3329549B1 patent drawingFigure 1A
  • EP3329549B1 patent drawingFigure 1B
  • EP3329549B1 patent drawingFigure 2

AI summary

An antenna is disclosed. The antenna comprises a feedline (101), a ground plane (102) and a radiator (103). The feedline has a path in a first plane, the path having a first arm (1011) and a second arm (1012) perpendicular to the first arm. The ground plane is provided in a second plane spaced apart from, and parallel to, the first plane. The ground plane has a ground plane slot (1021) therein with a path in the second plane. The path of the ground plane slot intersects the path of the feedline at a first position on the first arm and a second position on the second arm when the second plane is projected into the first plane. The radiator is separated from the feedline by the ground plane, and is provided in a third plane spaced apart from, and parallel to, the second plane.