Transmit Power Regulation via Reflected Power Detection
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Solution Overview
Problem
Electronic devices face challenges in regulating transmit power to comply with SAR limits due to impedance mismatches caused by human presence, which can result in excessive energy absorption by the human body.
Innovation Solution
A system that includes a signal source, directional couplers, and a processor to detect human presence by measuring reflected power and adjust transmit power accordingly, using voltage sampling and voltage standing wave ratio calculations to maintain compliance with SAR limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transmit power is increased to maintain communication quality, then signal strength is improved, but human body energy absorption increases exceeding SAR limits
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the reflected power from the antenna and adjusts the transmit power accordingly. When human presence is detected through changes in reflected power characteristics, the system automatically reduces transmit power to maintain SAR compliance while preserving communication functionality.
Solution Approach 2:
The system dynamically adjusts transmit power based on real-time detection of human presence. Rather than using a fixed power level, the transmit power is continuously adapted according to the detected conditions, allowing the system to optimize between communication quality and SAR compliance.
2Object-affected harmful factors
If transmit power is reduced to comply with SAR limits, then human body energy absorption is minimized, but communication quality deteriorates
Solution Approach 1:
The system dynamically adjusts transmit power based on real-time detection of human presence. Rather than using a fixed power level, the transmit power is continuously adapted according to the detected conditions, allowing the system to optimize between communication quality and SAR compliance.
Solution Approach 2:
The system changes the transmit power parameter based on detected human presence. By monitoring reflected power and identifying changes that indicate human proximity, the system adjusts the transmit power parameter to maintain both SAR compliance and acceptable communication quality.
3Use of energy by moving object
If impedance matching is optimized for maximum power transfer, then transmit efficiency is improved, but SAR compliance becomes difficult to maintain when human presence changes impedance
Solution Approach 1:
The system monitors reflected power to detect changes in antenna impedance caused by human presence. When impedance mismatch is detected, the feedback mechanism triggers transmit power reduction to maintain SAR compliance, balancing efficiency and safety.
Solution Approach 2:
The system changes the transmit power parameter in response to detected impedance changes. By monitoring reflected power characteristics, the system identifies when human presence alters the impedance match and adjusts power accordingly to maintain both efficiency and SAR compliance.
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
Effectively reduces transmit power when human presence is detected, ensuring compliance with SAR limits and minimizing energy absorption by the human body, thereby enhancing user safety.
Implementation Method 1
the processor may be configured to regulate the transmit power of the signal source based on a voltage standing wave ratio
Implementation Method 2
the antenna may become detuned, which may result in an impedance mismatch between the antenna and the signal source
Data Source
AI summary
Example implementations relate to detecting human presence in proximity of a user device. In example implementations, a portion of a first signal may be provided by a first directional coupler that is communicatively coupled to an antenna. A portion of a second signal may be provided by a second directional coupler that is communicatively coupled to a signal source. Transmit power of the signal source may be regulated based on the signal portions provided by the first and second directional couplers.