Compact Multiband Antenna Using Folded Element and Capacitive Feed

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Solution Overview

Problem

Existing multiband antennas are not compact enough for use in personal communication devices like smartphones and tablets, and they do not effectively utilize capacitive feeding to achieve multiple resonance behaviors with a single antenna element and a single capacitive feed.

Innovation Solution

A compact multiband antenna design featuring a conductive elongate antenna element connected to a groundplane and a conductive feeding element that couples capacitively, with the feeding element being significantly shorter than the resonant length at the lowest frequency, allowing for improved frequency bandwidth and compactness by forming a slot and using an auxiliary coupling branch to enhance coupling without reducing spacing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional multiband antenna designs are used, then multiple frequency ranges can be covered, but the antenna size becomes too large for personal communication devices

Engineering Contradiction:

Improvemultiband operation capabilityVSAvoidantenna size

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The antenna element is folded back on itself to form a compact nested structure, where portions of the antenna are positioned within or adjacent to each other, achieving multiband resonance in a reduced space envelope

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The antenna transitions from a planar configuration to a three-dimensional folded structure, utilizing vertical and lateral spacing to create multiple resonance paths without increasing the overall footprint area

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Volume of moving object

If a single antenna element is used with capacitive feeding, then device compactness is improved, but achieving effective multiband resonance becomes difficult

Engineering Contradiction:

Improveantenna compactnessVSAvoidmultiband resonance capability

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The single antenna element is divided into multiple functional portions (first portion, second portion, third portion) with different orientations and lengths, each contributing to resonance at different frequency bands while being fed by a single capacitive structure

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the antenna element are configured with specific geometric properties (parallel to groundplane edge, perpendicular to edge, folded back) to create localized resonance characteristics that collectively enable multiband operation

Inventive Principle:

Principle #3Local quality

3Volume of moving object

If the feeding element is made shorter to improve compactness, then the antenna becomes more compact, but coupling efficiency with the antenna element decreases

Engineering Contradiction:

Improvefeeding element lengthVSAvoidcapacitive coupling efficiency

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The feeding element is positioned at specific locations relative to different portions of the antenna element (adjacent to grounding point, parallel to second portion) to maximize capacitive coupling efficiency despite its reduced overall length

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The capacitive gap between the feeding element and antenna element acts as an intermediary coupling mechanism, allowing efficient energy transfer between the short feeding element and the folded antenna structure

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design achieves improved usable frequency bandwidth, multiband behavior, and compactness, allowing the antenna to operate effectively even when the groundplane is extended or bent around corners, with adjustable resonance frequencies and the ability to be electronically tunable.

Implementation Method 1

the feeding element is configured to extend substantially parallel to the first and second directions of the major portion of the antenna element and to couple capacitively with the antenna element during operation of the antenna device

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentUS10224630B2Multiband antenna

Publication Date: 2019.03.05 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

There is disclosed a multiband antenna device comprising a conductive elongate antenna element configured for electrical connection to a groundplane at a grounding point, and a conductive elongate feeding element configured for electrical connection to a radio transmitter/receiver at a feeding point. At least a major portion of the antenna element is configured to extend in a first direction and to double back on itself in a second, substantially counter-parallel direction forming a slot. The feeding point is adjacent to the grounding point, and the feeding element is configured to extend substantially parallel to the first and second directions of the major portion of the antenna element. The antenna device can operate in multiple frequency bands, and can be configured on a dielectric insulating former that fits compactly in a corner of a mobile communications handset housing.