Adaptive Antenna Tuning via Return Loss Phase Estimation

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Solution Overview

Problem

Conventional wireless transceivers require both power and phase detection circuits to monitor antenna reflection coefficients, increasing complexity and cost, as they typically measure both magnitude and phase components of incident and reflected signals for impedance matching.

Innovation Solution

Estimating the phase component of the reflection coefficient based on return loss measurements without directly measuring the phase, using a tunable matching circuit with a power detector and directional coupler, allowing for adaptive impedance matching without a phase detection circuit, thereby reducing complexity and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If both power and phase detection circuits are used to monitor antenna reflection coefficients, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvereflection coefficient measurementVSAvoiddetection circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the power detection function from the conventional dual-function detection system. By removing the phase detection circuit and retaining only power detection, the system achieves impedance matching through power measurements alone, significantly reducing circuit complexity while maintaining essential functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a tunable matching circuit as an intermediary element between the power detector and the antenna. This circuit enables the system to achieve impedance matching by adjusting its parameters based on power detection feedback, compensating for the absence of direct phase measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If both power and phase detection circuits are implemented, then impedance matching accuracy is improved, but manufacturing cost increases

Engineering Contradiction:
Improveimpedance matching accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive phase detection circuitry with a simpler power detection approach. By using only power detection combined with tunable matching circuit adjustment, the system achieves acceptable impedance matching accuracy at a lower manufacturing cost, trading off some precision for economic feasibility.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the measurement parameter from complex reflection coefficient (magnitude and phase) to simple power level. By monitoring power changes and adjusting the tunable matching circuit accordingly, the system achieves impedance matching without requiring expensive phase detection capabilities.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If power detection only is used to estimate reflection coefficient phase, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:
Improvedetection circuit complexityVSAvoidphase component estimation
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where power detection results are used to control the tunable matching circuit. By continuously monitoring power levels and adjusting the matching circuit parameters in response, the system indirectly achieves phase compensation through feedback control, compensating for the lack of direct phase measurement.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The tunable matching circuit serves as an intermediary that translates power detection information into impedance matching adjustments. This mediator enables the system to achieve accurate impedance matching by processing power detection data through the tunable circuit, bridging the gap between simple power measurement and complex impedance control.

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

Enables cost-effective and simplified adaptive impedance matching in wireless transceivers by estimating the phase component of the reflection coefficient from return loss measurements, reducing the need for phase detection circuits and enhancing transceiver efficiency.

Implementation Method 1

a power detector and directional coupler

Methodology Applied
Scientific EffectDirectional coupling:

Implementation Method 2

tunable matching circuit with a power detector and directional coupler, allowing for adaptive impedance matching

Methodology Applied
Scientific EffectImpedance matching: Electrical Resistance

Data Source

PatentEP3414837B1Apparatus and method for impedance measurement and adaptive antenna tuning
Publication Date: 2020.06.03 HUAWEI TECH CO LTD
  • EP3414837B1 patent drawingFigure 1~2
  • EP3414837B1 patent drawingFigure 3~4
  • EP3414837B1 patent drawingFigure 5

AI summary

It is possible to match the impedance of an antenna without directly measuring the phase. This is advantageous as it reduces the cost, and complexity, of wireless transceivers. In particular, the phase component of an antenna's reflection coefficient can be estimated based on return loss measurements. For example, a transceiver may measure an initial return loss of the antenna, adjust the impedance of at least one tunable element, and then measure one or more adjusted return losses of the antenna. The phase of the reflection coefficient can be estimated based on a difference between the initial return loss and the one or more adjusted return losses.