Wireless Transmitter Antenna Power Control for SAR Compliance

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Solution Overview

Problem

Current wireless device designs face challenges in controlling Specific Absorption Rate (SAR) due to the complexity and cost-ineffectiveness of existing solutions, which fail to meet advanced regulatory requirements while ensuring reduced user irradiation and maintaining adequate signal-to-noise ratio.

Innovation Solution

A wireless device with a transmitting portion featuring adjustable antennas and a sensor system to determine orientation, coupled with a control system that selectively controls power supply based on orientation, allowing for predetermined control of electromagnetic radiation intensity in specific directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transmission power is increased to provide acceptable signal-to-noise ratio, then communication performance is improved, but user irradiation and SAR increase

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoiduser irradiation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by controlling radiation intensity in specific directions rather than uniformly in all directions. The system identifies directions toward the user and reduces power in those specific directions while maintaining or increasing power in other directions, thereby improving SNR without proportionally increasing user irradiation

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by continuously adjusting radiation patterns and power distribution based on real-time orientation detection. The system dynamically adapts the transmission characteristics according to the device's orientation relative to the user, allowing optimization of SNR while controlling SAR under varying conditions

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If sophisticated distance sensing schemes are employed to limit SAR, then user irradiation control is improved, but device complexity increases

Engineering Contradiction:

Improveuser irradiationVSAvoidhardware complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical distance sensing systems with an orientation detection approach. Instead of using sophisticated sensors to measure distance, the system uses orientation detection combined with power control to achieve SAR limitation, thereby reducing hardware complexity while maintaining effectiveness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from distance-based to orientation-based power control. By detecting device orientation and adjusting power accordingly, the system achieves SAR control without requiring complex distance measurement hardware, thus reducing device complexity

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If transmission power is reduced to limit SAR, then user irradiation is decreased, but signal-to-noise ratio deteriorates

Engineering Contradiction:

Improveuser irradiationVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies local quality by directing reduced power specifically toward the user while maintaining higher power in directions away from the user. This selective power distribution reduces user irradiation while preserving sufficient signal strength for acceptable SNR through spatial differentiation

Inventive Principle:

Principle #3Local quality

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 solution effectively limits user irradiation and SAR by adjusting antenna power according to device orientation, ensuring compliance with regulatory limits while maintaining communication performance.

Implementation Method 1

a sensor system for determining an orientation of the transmitting portion

Methodology Applied

Scientific EffectOrientation sensing:

Implementation Method 2

each radiation pattern defining dependence of intensity of electromagnetic radiation generated by an antenna on direction and distance from the transmitting portion

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentUS8744539B2Method and apparatus for controlling radiation characteristics of transmitter of wireless device in correspondence with transmitter orientation

Publication Date: 2014.06.03 NETGEAR INC

AI summary

The invention provides an apparatus and a corresponding method for controlling radiation characteristics of a transmitter of a wireless device. The wireless device includes a transmitting portion that includes one or more antennas that are characterized by one or more radiation patterns. The wireless device further comprises a sensor system for determining an orientation of the transmitting portion and a control system that is operatively coupled to the sensor system and configured to control the supply of power to each antenna depending on the orientation of the transmitting portion.