Multi-Frequency Band Antenna Bottom Positioning for SAR Reduction
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Solution Overview
Problem
Existing cellular phone antennas are close to the user's head, leading to increased radio frequency energy absorption and potential safety concerns regarding specific absorption rate (SAR), and there is a need for smaller device sizes while maintaining low SAR values.
Innovation Solution
A multi-frequency band antenna configuration with a main loop conductor, branch conductors, and a tuning branch conductor is positioned at the bottom of the mobile device's housing, reducing proximity to the user's head and allowing for a compact design that meets SAR requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is positioned closer to the user's head for compact device design, then the device footprint is reduced, but the specific absorption rate (SAR) increases due to higher RF energy absorption
Solution Approach 1:
The patent positions the antenna at the bottom of the device rather than placing it at the top or sides, utilizing the vertical dimension and bottom surface space. This dimensional repositioning allows the antenna to be integrated into the device footprint without increasing overall size, while simultaneously creating greater distance from the user's head during typical holding positions, thereby reducing SAR exposure
2Volume of moving object
If internal antennas are used to reduce device footprint, then the device size is reduced, but the antenna is in closer proximity to the user's head increasing RF energy absorption
Solution Approach 1:
The patent applies local quality by specifically positioning the antenna structure at the bottom portion of the device housing, creating a localized arrangement where the antenna elements are spatially separated from the user's head area. This localized positioning strategy maintains the internal antenna configuration for compactness while addressing the harmful RF absorption issue through strategic spatial distribution
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 RF energy absorption, provides reliable antenna performance, and allows for a smaller device footprint while ensuring compliance with SAR regulations.
Implementation Method 1
the amount of radio frequency (RF) energy radiation absorbed by the body will typically increase
Data Source
AI summary
A mobile wireless communications device may include a housing and a multi-frequency band antenna carried within the housing. The multi-frequency band antenna may include a main loop conductor having a gap therein defining first and second ends of the main loop conductor, a first branch conductor having a first end connected adjacent the first end of the main loop conductor and having a second end defining a first feed point, and a second branch conductor having a first end connected adjacent the second end of the main loop conductor and a second end defining a second feed point. A third branch conductor has a first portion within the main loop conductor, and a second portion connected to the second feed point. A tuning branch conductor may have a first end connected to the main loop conductor between the respective first ends of the first and second branches.