Microwave Imaging Skin Reflection Cancellation
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Solution Overview
Problem
Microwave imaging of the human body is hindered by the need to identify in-depth features through outer attenuating body layers, where faint signal variations from in-depth features are masked by reflections from the skin and antennas, leading to skin artifact removal methods that degrade image quality and require identical antennas or mechanical rotation, which are impractical.
Innovation Solution
A method for enhancing microwave imaging using an array of antennas that collects microwave responses, determines reference pairs for antenna pairs, and performs skin reflection estimation and cancellation based on weighted signals from other antenna pairs, accounting for non-identical transmit-receive paths, without requiring physical rotation of the array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If skin reflection cancellation methods are used to remove skin artifacts, then skin reflection is reduced, but image quality is degraded and artifacts are generated
Solution Approach 1:
The patent uses reference antenna pairs to create a copy of the skin reflection signal that can be subtracted from the measurement antenna pairs. By copying the skin reflection characteristics from reference pairs (which contain only skin reflection without target signals) and subtracting this copy from the measurement pairs, the method removes skin artifacts while preserving target signals, thus maintaining image quality while reducing skin reflections
Solution Approach 2:
The patent segments the antenna array into two distinct groups: reference antenna pairs and measurement antenna pairs. Reference pairs are specifically selected to capture only skin reflection signals, while measurement pairs capture both skin reflection and target signals. This segmentation allows separate processing of skin reflection components from target detection components, enabling effective skin artifact removal without degrading image quality
2Object-affected harmful factors
If differential rotation method is used to remove skin clutter, then skin reflection is cancelled, but targets near central axis are removed and image quality is degraded
Solution Approach 1:
Instead of using physical rotation that removes targets, the patent creates a virtual copy of the skin reflection signal through reference antenna pairs. This copied skin reflection signal is then subtracted from measurement signals, achieving skin clutter removal without the harmful side effect of eliminating targets near the central axis, thereby preserving measurement precision
3Object-affected harmful factors
If array rotation is used to remove skin artifacts, then skin reflection is reduced, but mechanical complexity increases and positioning accuracy is difficult to maintain
Solution Approach 1:
The patent replaces the mechanical rotation system with a computational approach. Instead of physically rotating the antenna array to achieve skin reflection cancellation, the method uses signal processing techniques with reference and measurement antenna pairs to mathematically remove skin artifacts. This substitution eliminates mechanical complexity while maintaining the ability to reduce skin reflections, and also avoids the positioning accuracy issues associated with mechanical rotation
4Object-affected harmful factors
If weighted average of signals from different locations is used to remove skin artifacts, then skin reflection is reduced, but antenna non-identicality causes significant degradation
Solution Approach 1:
The patent creates a precise copy of the skin reflection signal using reference antenna pairs that are specifically designed to capture only skin reflection. This copied signal is then subtracted from measurement signals, achieving accurate skin artifact removal even when antennas are not identical. The method compensates for antenna non-identicality by using the reference pairs as templates for skin reflection characteristics, maintaining high accuracy in skin artifact removal despite manufacturing variations
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 approach improves the robustness of microwave imaging by effectively removing skin reflections without degrading the image quality, allowing for accurate detection of in-depth features without assuming identical antennas or mechanical rotation, and reduces artifacts in the reconstructed image.
Implementation Method 1
the reflections (impulse response) between antenna pairs can be estimated
Implementation Method 2
a wide band signal is used to sample the transfer function between pairs of antennas over a large frequency range
Data Source
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AI summary
A microwave imaging sensor is disclosed which is resilient to background and skin clutter. Resilience is obtained by cancellation of skin reflections without mechanical displacement of the microwave antenna array or the subject, by utilizing reflections from other antennas and compensating for differences in propagation. The cancellation takes into consideration the expected strength of the reflection at different points in time and for different pairs, in order to minimize the effects on the image, and particularly on image reconstruction of symmetric targets.