VSWR-Based Antenna Object Detection for Adaptive RF Power
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Solution Overview
Problem
Existing wireless circuitry in electronic devices struggles to accurately estimate distances to external objects, particularly in close proximity, and distinguishes between animate and inanimate objects, leading to potential regulatory violations and performance limitations.
Innovation Solution
Incorporating a voltage standing wave ratio (VSWR) sensor along the radio-frequency transmission line to measure variations in VSWR, allowing processors to identify whether an external object is animate or inanimate, and adjust transmit power levels accordingly to comply with regulatory limits and enhance wireless performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless circuitry transmits radio-frequency signals at maximum power to maximize wireless performance, then wireless performance is improved, but regulatory limits on radio-frequency energy exposure may be exceeded when animate objects are present
Solution Approach 1:
The system continuously monitors VSWR measurements and uses this feedback to detect the presence of animate objects. When an animate object is detected through VSWR variation analysis, the system automatically reduces transmit power to comply with regulatory limits, and when no animate object is present, it maintains maximum power for optimal wireless performance.
Solution Approach 2:
The transmit power level is made dynamic rather than static, adjusting in real-time based on the detection of animate objects. The system transitions between maximum power mode (when no animate objects are present) and reduced power mode (when animate objects are detected), optimizing both performance and compliance.
2Measurement precision
If wireless circuitry uses traditional distance estimation methods to detect external objects, then object detection is performed, but accurate detection in close proximity is difficult due to blind spots
Solution Approach 1:
The system uses VSWR measurements as an intermediary indicator to detect the presence of objects in the near field. Instead of directly measuring distance, the system monitors changes in VSWR caused by objects affecting the radio-frequency transmission line, enabling detection in the blind spot region where traditional methods fail.
Solution Approach 2:
The patent replaces traditional time-of-flight or phase-based distance estimation methods with an electrical measurement approach using VSWR sensing. This substitution enables detection of objects in close proximity by measuring electrical characteristics of the transmission line rather than relying on signal propagation time.
3Loss of information
If wireless circuitry detects external objects using radio-frequency signals, then object presence is detected, but the ability to distinguish between animate and inanimate objects is limited
Solution Approach 1:
The system uses partial information from VSWR measurements over time to make classification decisions. By analyzing the variation pattern of VSWR measurements rather than requiring complete object characterization, the system can distinguish animate from inanimate objects using a relatively simple implementation.
Solution Approach 2:
The system performs periodic VSWR measurements over time to gather sufficient data for classification. By taking multiple measurements at different time points and analyzing the variation, the system can distinguish between animate objects (which cause time-varying VSWR) and inanimate objects (which cause static VSWR changes).
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 VSWR sensor enables precise detection of external objects, differentiating between animate and inanimate objects, ensuring compliance with regulatory energy exposure limits while maximizing wireless performance by adjusting transmit power levels.
Implementation Method 1
A voltage standing wave ratio (VSWR) sensor may be disposed along the radio-frequency transmission line. The VSWR sensor may gather VSWR measurements from the transmitted radio-frequency signals during a sampling period.
Data Source
AI summary
An electronic device may include a voltage standing wave ratio (VSWR) sensor disposed along a radio-frequency transmission line between a signal generator and an antenna. The VSWR sensor may gather VSWR measurements from radio-frequency signals transmitted by the signal generator over the transmission line. Control circuitry may identify a variation in the VSWR measurements over time and may compare the variation to a threshold value to determine whether an external object in the vicinity of the antenna is animate or inanimate. The control circuitry may reduce the maximum transmit power level of the antenna when the external object is animate and may maintain or increase the maximum transmit power level when the external object is inanimate. This may serve to maximize the wireless performance of the electronic device while also ensuring that the device complies with regulatory limits on radio-frequency energy exposure.