Modified Ground Plane Antenna Bandwidth

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Solution Overview

Problem

Developing an antenna design that supports multiple frequency bands while maintaining a low profile and compact size is challenging, as existing solutions either occupy excessive PCB space or fail to achieve true broadband performance.

Innovation Solution

A modified ground plane approach that includes a small, orthogonal ground plane section positioned between the main ground plane and radiating element, with an extended section perpendicular to the ground plane, which improves antenna performance without increasing thickness or volume, and includes a shorting pin for additional current paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a monopole antenna is folded into the ground plane to create a two-dimensional planar structure, then broadband self-matching is improved, but the antenna occupies a large surface area on the PCB board

Engineering Contradiction:
Improvebroadband self-matchingVSAvoidPCB surface area
Core Design Contradiction:
Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent introduces a vertical dimension by extending the ground plane 90 degrees to form a corner-like reflector structure. This transforms a two-dimensional planar ground plane into a three-dimensional structure, achieving broadband performance without increasing the PCB footprint area.

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

2Reliability

If conventional ground plane folding approaches are used to improve antenna performance, then radiation characteristics are enhanced, but true broadband performance below 3GHz is not achieved

Engineering Contradiction:
Improveantenna radiation performanceVSAvoidbroadband performance below 3GHz
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent modifies the ground plane geometry by creating a corner-like reflector with specific dimensional parameters (extension length, angle of folding) to achieve resonant frequencies that enable true broadband performance including frequencies below 3GHz, rather than simply folding the ground plane in conventional ways.

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If the antenna structure is made compact and low-profile, then device thickness is reduced, but impedance matching and bandwidth are compromised

Engineering Contradiction:
Improveantenna volumeVSAvoidimpedance matching and bandwidth
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

By extending the ground plane vertically to form a corner reflector structure, the patent achieves improved impedance matching and bandwidth without increasing the horizontal footprint or overall device thickness, effectively utilizing the vertical dimension for performance enhancement.

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

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 enables broadband matching across multiple frequency bands without the need for complex matching networks, enhancing antenna performance while maintaining a slim form factor suitable for handheld devices.

Implementation Method 1

an extension of the ground plane projecting into the antenna space, the ground plane extension defining a second resonant length that includes at least part of its own length and at least part of a length of the ground plane structure

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2649680B1Modified ground plane (MGP) approach to improving antenna self-matching and bandwidth
Publication Date: 2018.03.07 BLACKBERRY LTD
  • EP2649680B1 patent drawingFigure 1~2
  • EP2649680B1 patent drawingFigure 3
  • EP2649680B1 patent drawingFigure 4A

AI summary

An antenna design technique which allows antennas to be self-matched while supporting multi-band and broadband operations. The technique includes adding a raised and curved ground plane section electrically coupled to the ground plane. The curved ground plane section allows for a smooth transition of the surface current hence a boarder bandwidth is achieved. A slit positioned between the ground plane and the ground plane section can also be used to further improve the antenna bandwidth. The technique does not increase the antenna thickness neither its volume, thus allowing application in slim handheld device applications such as flip phones. Using this technique, a narrow band antenna is made broadband to cover several frequency bands of interest. The technique is applied to a quad-band antenna to broaden its bandwidth to become a sept-band antenna. The technique is used to also improve the antenna match at all the seven bands it supports.