Multi-Antenna Transmit Hopping to Reduce SAR Hot Spots

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Solution Overview

Problem

Wireless communication devices face challenges in meeting regulatory SAR requirements without reducing TX power and using expensive SAR sensors, which affect system performance and link reliability.

Innovation Solution

Implementing multiple antenna configurations and antenna switching mechanisms to hop the transmit signal at regular intervals, reducing hot spots and eliminating the need for SAR sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If SAR sensors are used to detect human proximity and reduce TX power to meet SAR requirements, then SAR compliance is achieved, but TX power is reduced impacting system performance and link reliability

Engineering Contradiction:

ImproveSAR complianceVSAvoidlink reliability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent segments the transmit function across multiple antennas, switching between them in different time slots. This allows the system to maintain high TX power on the active antenna while ensuring SAR compliance through temporal distribution of transmit energy, avoiding the need for power reduction that would harm link reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic antenna switching where different antennas are activated in alternating time slots. This periodic action distributes the SAR exposure over time and space, allowing each antenna to transmit at full power during its active slot while maintaining overall SAR compliance, thus preserving link reliability

Inventive Principle:

Principle #19Periodic action

2Object-affected harmful factors

If SAR sensors are used to detect human proximity and reduce TX power, then SAR compliance is achieved, but device cost increases due to expensive sensors

Engineering Contradiction:

ImproveSAR complianceVSAvoiddevice cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent makes the antenna system self-regulating for SAR compliance through automated antenna switching based on channel quality feedback. The system uses existing communication protocols and signal measurements to determine when to switch antennas, eliminating the need for external SAR sensors and reducing device cost while maintaining SAR compliance

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If SAR sensors are used for proximity detection, then SAR compliance is achieved, but device complexity increases due to additional sensors

Engineering Contradiction:

ImproveSAR complianceVSAvoiddesign complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent makes the existing antenna system perform the dual function of both communication and SAR compliance management. The same antennas used for data transmission are switched based on SAR considerations, and existing channel quality measurements serve dual purposes for both communication optimization and antenna switching decisions, eliminating the need for separate SAR sensing subsystems and reducing design complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Object-affected harmful factors

If TX power is reduced to meet SAR requirements, then SAR compliance is achieved, but system performance deteriorates

Engineering Contradiction:

ImproveSAR complianceVSAvoidsystem performance

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent segments the transmit function across multiple antennas in the time domain, allowing each antenna to transmit at full power during its designated time slot. This temporal segmentation maintains high overall system performance while distributing SAR exposure, avoiding the performance degradation that would result from continuous power reduction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the temporal parameter of antenna activation, switching between different antennas in different time slots rather than continuously reducing power. This parameter change allows the system to maintain high transmit power levels when needed for performance while ensuring SAR compliance through the time-distributed nature of the transmission

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12483994B2Antenna hopping for specific absorption rate (SAR) reduction

Publication Date: 2025.11.25 ALTERA CORP

AI summary

A method comprising: retrieving a predefined power threshold; determining a transmission power of a transmitting antenna, wherein the transmitting antenna is actively transmitting a signal; retrieving a predefined transmission time interval; determining that the transmission power exceeds the predefined power threshold; determining a duration of transmitting the signal; comparing the duration with the predefined transmission time interval; and switching transmitting the signal from the transmitting antenna to a further antenna when the duration equals the predefined transmission time interval.