Polarimetric Radar Classification Using Circular Polarization Imaging
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Solution Overview
Problem
Existing radar systems using linearly polarized signals struggle with ambiguous object classification and lack of clarity in radar images, particularly in differentiating between various objects, and are prone to 'ghost targets' due to multipath propagation and side lobes.
Innovation Solution
Utilizing elliptically or circularly polarized transmission signals to generate distinct radar images for object classification, employing polarimetric radar sensors with full polarimetric receivers to analyze pattern recognition and differentiate between object features, and implementing phase-coded transmission from multiple transmitters to reduce the need for multiple receiver channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linearly polarized signals are used for object classification, then the radar system structure is simple, but the object classification accuracy is low and results are ambiguous
Solution Approach 1:
The patent changes the polarization parameter of the transmission signal from linear to elliptical or circular polarization. This parameter change enables the generation of multiple independent radar images (co-polarization and cross-polarization) that provide more discriminative features for object classification, thereby improving classification accuracy while managing system complexity through signal processing rather than hardware multiplication
Solution Approach 2:
The patent introduces the polarization dimension by using elliptical or circularly polarized signals, which create additional independent measurement channels (co-polarization and cross-polarization images). This dimensional expansion provides more information for object classification without requiring multiple physical radar systems, thus improving accuracy while controlling complexity
2Loss of information
If multiple receiver channels are used to receive different polarization components, then the polarimetric radar data is complete, but the device complexity increases
Solution Approach 1:
The patent merges the reception of different polarization components into a single receiver channel by using elliptical or circularly polarized transmission signals. The single channel receives both co-polarization and cross-polarization information, which are then separated and processed independently through signal processing techniques, thereby maintaining complete polarimetric data while reducing hardware complexity
Solution Approach 2:
The single receiver channel is designed to perform multiple functions by receiving both co-polarization and cross-polarization signal components. This multi-functional approach allows one channel to capture complete polarimetric information that would traditionally require multiple specialized channels, reducing overall system complexity
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
Enhances object classification accuracy, reduces ambiguity, and improves target detection by generating independent radar images for co- and cross-polarization, allowing for better differentiation of object features and detection of 'ghost targets', while maintaining high angular resolution and enabling distance-based object height determination and road surface friction measurement.
Implementation Method 1
The polarimetric radar sensor according to the invention uses elliptically or circularly polarized transmission signals for which correspondingly different reflection signals are used to generate different radar images
Implementation Method 2
DE 10 2013 102 424 A1 describes a polarimetric radar consisting of a transmitting arrangement that emits circularly polarized waves via transmitting antennas and a receiver arrangement that receives the reflected circularly polarized wave components
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
The invention relates to a method for object classification which comprises the following steps for providing an elliptically or circularly polarized transmission signal which is transmitted to the object to be classified: generating a first radar image from the copolarly polarized reflection signal and generating a second radar image from the cross-polarized reflection signal and comparing the first radar image with the second radar image.