Parasitic Antenna Isolation for Compact Wireless Devices

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Solution Overview

Problem

In artificial reality systems, improving antenna isolation between multiple wireless links operating at the same frequency band is challenging due to interference and crosstalk, especially in compact form factors where spatial and polarization diversity are limited.

Innovation Solution

The use of a parasitic element mounted on a separate ground plane, connected to a switch or phase shifter, and tuned to resonate with main antennas to enhance isolation between antennas without increasing physical separation or changing polarizations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spatial separation between antennas is increased to reduce interference, then antenna isolation is improved, but device form factor increases and compactness is lost

Engineering Contradiction:

Improveantenna isolationVSAvoiddevice form factor

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

A parasitic antenna element is introduced as an intermediary component positioned between the first and second antennas. This parasitic element couples to both antennas through electromagnetic induction and acts as a mediator to cancel harmful surface currents and reduce mutual interference, achieving improved antenna isolation without increasing the physical distance between the main antennas

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The parasitic antenna element's electrical parameters (length, width, position, orientation) are optimized to resonate at the operating frequency and create opposing surface currents that cancel the harmful currents on the ground plane. By adjusting these parameters, the system achieves effective antenna isolation while maintaining a compact form factor

Inventive Principle:

Principle #35Parameter changes

2Reliability

If polarization diversity is used to improve antenna isolation, then interference is reduced, but device complexity increases due to additional components

Engineering Contradiction:

Improveantenna isolationVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The parasitic antenna element serves as a simple intermediary structure that passively reduces interference through electromagnetic coupling. Unlike active polarization diversity systems that require switches, phase shifters, and complex signal processing, this parasitic element approach uses passive electromagnetic induction to achieve isolation, significantly reducing system complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The parasitic antenna element automatically adjusts its coupling to both main antennas through electromagnetic resonance at the operating frequency. The system self-regulates the isolation effect without requiring external control signals, switches, or complex adjustment mechanisms, thereby minimizing device complexity

Inventive Principle:

Principle #25Self-service

3Volume of moving object

If physical separation between antennas is maintained small for compact design, then device portability is improved, but antenna isolation deteriorates due to increased interference

Engineering Contradiction:

Improvedevice compactnessVSAvoidantenna interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The parasitic antenna element is positioned between the two main antennas in close proximity and couples to both through electromagnetic induction. It generates opposing surface currents that cancel the harmful interference between the closely-spaced antennas, enabling compact design while maintaining isolation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The parasitic antenna element exploits the harmful electromagnetic coupling between closely-spaced antennas by converting it into a beneficial effect. The same strong coupling that causes interference is used to induce opposing currents in the parasitic element, which then cancel the harmful surface currents on the ground plane, turning the interference problem into a solution

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 achieves improved antenna isolation, reducing surface currents and providing flexibility in signal routing, while allowing for fine-tuning and adaptation to changes in system components, thereby enhancing user experience by minimizing latency and interference.

Implementation Method 1

The parasitic antenna may be disposed between the first and second antennas... The impedance tuners may be adjusted to configure the first, second and parasitic antennas to achieve a same resonant frequency

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11594810B1Antenna isolation using parasitic element in wireless devices

Publication Date: 2023.02.28 META PLATFORMS TECHNOLOGIES LLC

AI summary

Disclosed herein includes a wireless device including a first antenna configured to perform wireless communication, a second antenna configured to perform wireless communication, and a parasitic antenna. The first antenna may have a feed connected to a first impedance tuner that is connected to a first ground planes. The second antenna may have a feed connected to a second impedance tuner. The parasitic antenna may be disposed between the first and second antennas, with a feed connected to a third impedance tuner that is connected to a second ground plane. The first, second and third impedance tuners may be adjusted to configure the first, second and parasitic antennas to achieve a same resonant frequency.