Floating Beam Shaping Elements for Antenna SAR Reduction
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Solution Overview
Problem
The challenge in designing cellular communications devices is to create antennas that provide desired operating characteristics within the limited space available, while also ensuring compliance with SAR and HAC requirements, especially as devices become smaller and internal antennas are positioned closer to the user's ear, potentially elevating radiation exposure and compatibility issues.
Innovation Solution
The implementation of a mobile wireless communications device with a printed circuit board (PCB) carrying a bottom-mounted antenna and pairs of electrically floating, conductive antenna beam shaping elements, which are laterally offset and co-planar, helps direct the antenna beam away from the user, reducing radiation exposure and improving hearing aid compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If internal antennas are positioned closer to the user's ear to accommodate smaller device form factors, then device compactness is improved, but radiation exposure and SAR compliance become problematic
Solution Approach 1:
A hearing aid compatibility component is introduced as an intermediary element between the antenna and the user's ear. This component includes a conductive element that creates a controlled electromagnetic coupling to redirect or shield harmful radiation, thereby protecting the user while allowing the antenna to remain in a compact position within the device housing.
Solution Approach 2:
The harmful radiation effect is extracted and isolated by introducing a dedicated hearing aid compatibility component that specifically addresses and mitigates the radiation issue. This allows the antenna system to function independently without directly exposing the user to harmful radiation levels.
2Object-affected harmful factors
If external antennas are used to maintain distance from the user's head for SAR compliance, then radiation exposure is reduced, but device durability deteriorates due to susceptibility to damage
Solution Approach 1:
The antenna system is nested within the device housing rather than extending externally. The hearing aid compatibility component is nested between the antenna element and the external environment, providing protection while maintaining the antenna's functional position. This nested configuration protects the antenna from physical damage while keeping it integrated within the device structure.
3Volume of moving object
If antenna elements are placed in close proximity to each other to reduce device size, then device compactness is improved, but electromagnetic interference between elements increases
Solution Approach 1:
The hearing aid compatibility component provides localized electromagnetic management in the specific region where antenna elements are positioned close together. The conductive element creates a controlled electromagnetic environment that manages interference between closely spaced antenna elements, allowing compact configuration without excessive interference.
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 the specific absorption rate (SAR) and enhances hearing aid compatibility by spacing the antenna farther from the user's ear and brain, while accommodating various form factors and housing shapes, thus addressing the limitations of traditional top-mounted internal antennas.
Implementation Method 1
electromagnetic radiation generated by the first in-built driven antenna element is enhanced in a direction away from a side of the casing intended to be facing a user
Data Source
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AI summary
A mobile wireless communications device may include a portable housing, a printed circuit board (PCB) carried within the portable housing, wireless transceiver circuitry carried by the PCB within the portable housing, and an antenna carried by the PCB within the portable housing and connected to the wireless transceiver circuitry. The device may further include a first pair of electrically floating, electrically conductive, spaced apart, antenna beam shaping elements adjacent the antenna and spaced apart therefrom. A second pair of electrically floating, electrically conductive, spaced apart, antenna beam shaping elements may be adjacent the antenna and spaced apart therefrom. The first pair of antenna beam shaping elements may be positioned in an offset relationship relative to the second pair of antenna beam shaping elements.