Antenna Switching for SAR Reduction in Wireless Devices
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Solution Overview
Problem
Existing electronic devices face challenges in reducing Specific Absorption Rate (SAR) while maintaining communication performance, as high power transmission can exceed allowable SAR limits, leading to reduced antenna power and compromised communication performance when near a human body.
Innovation Solution
A flexible electronic device with a communication unit, multiple antennas, a switch unit, and a processor that sequentially switches antennas based on a predetermined schedule, measuring receive signal strength and adjusting switching times to ensure SAR compliance and maintain communication performance, especially when an external object approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If antenna power is increased to improve communication performance, then communication performance is improved, but SAR increases and may exceed allowable reference values
Solution Approach 1:
The patent divides the antenna system into multiple antennas with different main emission directions. Instead of using a single antenna at high power, the system segments the transmission across multiple antennas, allowing directional control of electromagnetic radiation and reducing SAR in sensitive directions while maintaining communication performance.
Solution Approach 2:
The patent implements dynamic antenna switching based on real-time sensor feedback about device orientation and external objects. The system dynamically adjusts which antenna is active and modifies transmission parameters according to the current spatial configuration, optimizing the balance between communication performance and SAR reduction.
2Object-affected harmful factors
If antenna power is reduced to decrease SAR, then SAR is reduced, but communication performance deteriorates
Solution Approach 1:
The patent applies local quality by directing antenna beams preferentially away from the human body and toward external targets. Different regions of space receive different transmission characteristics - directions away from the body receive higher power while directions toward the body receive reduced power, maintaining communication performance while reducing SAR.
Solution Approach 2:
The patent employs periodic switching between multiple antennas with different emission patterns. By cycling through different antenna configurations, the system maintains average communication performance while reducing peak SAR exposure through temporal diversification of the radiation pattern.
3Object-affected harmful factors
If multiple antennas with different emission directions are used to reduce SAR, then SAR is reduced, but device complexity increases
Solution Approach 1:
The patent uses sensor feedback about device orientation and the presence of external objects to automatically control antenna switching. This feedback mechanism simplifies the control complexity by using straightforward sensor readings to determine antenna selection, avoiding the need for complex algorithms while achieving SAR reduction.
Solution Approach 2:
The patent makes the antenna system multi-functional by using the same antenna array for both communication and SAR management purposes. The sensor unit and switch unit serve dual functions of monitoring the environment and controlling antenna selection, reducing overall device complexity despite the multiple antennas.
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 reduces SAR while enhancing communication performance by strategically switching antennas with different main emission directions, ensuring compliance with SAR reference values and minimizing performance degradation near a human body.
Implementation Method 1
When an antenna transmits electromagnetic waves with high power
Implementation Method 2
said sensor information corresponds to a bending signal of the flexible electronic device
Data Source
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AI summary
An electronic device and method are provided for switching an antenna for SAR reduction. The method includes sequentially switching, based on a predetermined schedule, a plurality of antennas having different main emission directions, when transmitting a wireless signal. Said schedule may be updated based on the received signal strength of each antenna and/or proximity sensor signals, indicating the blocking of an antenna by a user holding the electronic device.