Wearable Antenna Phase Cancellation for SAR Reduction
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Solution Overview
Problem
Wearable electronic apparatuses face challenges in reducing Specific Absorption Rate (SAR) while maintaining antenna efficiency, as the antenna positioning near the user's head leads to increased SAR and degraded efficiency due to radio wave absorption.
Innovation Solution
The electronic apparatus features two antennas positioned on either side of the user's head, with a transceiver circuit that distributes power and generates a phase difference between them, reducing SAR and enhancing antenna efficiency by canceling out radio waves at the user's head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the antenna is positioned in proximity to the user's head for wearable use, then the radio communication function is enabled, but the SAR increases exceeding the standard value and antenna efficiency degrades
Solution Approach 1:
The patent divides the single antenna system into two separate antennas positioned on opposite sides of the user's head. This segmentation allows the radio waves to be transmitted from multiple locations, reducing the concentration of electromagnetic energy at any single point near the head, thereby lowering SAR while maintaining communication functionality.
Solution Approach 2:
The patent employs asymmetric positioning of the two antennas on opposite sides of the head, creating an asymmetric radiation pattern that distributes electromagnetic energy more evenly across the head surface. This asymmetric configuration prevents focal points of high energy concentration, reducing peak SAR values compared to a single centralized antenna.
2Ease of operation
If the antenna is positioned in proximity to the user's head, then the wearable function is achieved, but the radio wave is absorbed by the user's head causing degraded antenna efficiency
Solution Approach 1:
By segmenting the antenna system into two distributed antennas, the patent reduces the energy burden on each individual antenna. Each antenna transmits at lower power levels, reducing the amount of energy absorbed by the head while collectively maintaining the required communication signal strength, thus improving overall antenna efficiency.
Solution Approach 2:
The patent transitions from a single-point antenna configuration to a distributed spatial configuration across two dimensions (opposite sides of the head). This dimensional change creates multiple propagation paths for radio waves, reducing absorption losses and improving energy efficiency through spatial diversity.
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 configuration effectively reduces SAR and improves antenna efficiency by distributing power between the two antennas, ensuring better radiation patterns and lower field intensity near the user's head, thus meeting standard SAR values while maintaining efficient communication.
Implementation Method 1
a transceiver circuit for supplying power to the first antenna and the second antenna
Implementation Method 2
canceling out radio waves at the user's head
Data Source
AI summary
An electronic apparatus capable of reducing SAR and, simultaneously, suppressing degradation of antenna efficiency is provided. To that end, an electronic apparatus includes a first temple to be positioned on one side of the user's head when the electronic apparatus is worn on the user's head, a second temple to be positioned on the other side of the user's head when the electronic apparatus is worn on the user's head, an first antenna formed in the first temple, an second antenna formed in the second temple, and a transceiver circuit for supplying power to the first antenna and the second antenna.