Antenna Stack RF Switch Grounding for SAR and Coupling
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Solution Overview
Problem
In mobile communication devices with multiple antennas, mutual coupling and Specific Absorption Rate (SAR) hotspots can deteriorate performance and pose health risks, while also requiring compliance with regulatory SAR limits, which existing technologies have not adequately addressed.
Innovation Solution
A radio frequency (RF) switch is configured to ground unnecessary antenna feeds, reducing mutual coupling and SAR hotspots by using shorting elements connectable to an electrical ground, allowing multiple frequency operations and MIMO capabilities with lower mutual coupling and SAR hotspots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple antennas are located in close proximity to fit compact device form factors, then device portability is improved, but mutual coupling between antennas increases deteriorating performance
Solution Approach 1:
The patent employs RF switches to dynamically reconfigure antenna connections based on operational requirements. The switches can connect antenna elements to different feeds or ground them, allowing the antenna system to adapt its configuration and reduce mutual coupling effects when antennas are in close proximity, thereby maintaining performance in compact device form factors.
2Productivity
If multiple antennas operate simultaneously in close proximity, then communication capacity is improved, but SAR hotspots increase posing health risks
Solution Approach 1:
The RF switch system enables dynamic control of antenna operation states. When SAR hotspots are detected or anticipated, the controller can ground specific antenna feeds through the RF switches, reducing radiation from those elements and thereby lowering SAR exposure while maintaining communication capacity through remaining active antennas.
Solution Approach 2:
The system incorporates SAR monitoring capabilities that provide feedback to the controller. Based on this feedback, the controller adjusts RF switch configurations to ground feeds associated with high SAR regions, creating a closed-loop system that actively manages and reduces SAR hotspots while maintaining communication performance.
3Reliability
If RF switches are added to ground unnecessary antenna feeds, then mutual coupling is reduced improving performance, but device complexity increases
Solution Approach 1:
The RF switches are integrated into the existing antenna feed network architecture, serving multiple functions: grounding unnecessary feeds to reduce mutual coupling, enabling antenna diversity selection, and supporting MIMO operations. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving performance improvement.
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
The solution improves antenna performance, reduces SAR hotspots, and ensures compliance with regulatory limits by effectively managing antenna coupling and radiation exposure in compact devices.
Implementation Method 1
A radio frequency (RF) switch is configured to ground unnecessary antenna feeds, reducing mutual coupling and SAR hotspots by using shorting elements connectable to an electrical ground
Implementation Method 2
mutual coupling and Specific Absorption Rate (SAR) hotspots can deteriorate performance and pose health risks
Data Source
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AI summary
An antenna stack and device is described. In an embodiment, a device comprises: a first antenna element coupled to a first antenna feed, the first antenna feed being coupled to a first feed line via a first impedance matching circuit; a second antenna element coupled to a second antenna feed, the second antenna feed being coupled to a second feed line via a second impedance matching circuit; and a radio frequency (RF) switch configurable into states; wherein in a first state, the switch is configured to ground the first antenna feed; in a second state, the switch is configured to be in a non-connection state, wherein neither the first antenna feed nor the second antenna feed is grounded; and in a third state, the switch is configured to ground the second antenna feed.