Analysis and exploitation of multipath ghosts in radar target image classification

Area of Science:

• Radar Imaging
• Signal Processing
• Electromagnetics

Background:

• Multipath reflections in radar systems create "ghost" images distinct from the direct target echo.
• Understanding the characteristics of these multipath ghosts is crucial for accurate target identification.

Purpose of the Study:

• To analyze the relationship between multipath ghosts and direct target images in radar.
• To define a multipath point spread function (PSF) for ghost localization.
• To investigate the potential of utilizing ghosts for enhanced target classification.

Main Methods:

• Definition of a multipath point spread function (PSF) accounting for specular reflections.
• Analysis of PSF to determine ghost focusing capabilities in different radar configurations (far-field SAR vs. full array).
• Demonstration of ghost exploitation using experimental data and a naïve Bayesian classifier.

Main Results:

• The study defines a multipath PSF enabling localization of ghost images.
• Certain ghosts are focusable only in the far-field synthetic aperture radar (SAR) scenario, not with full arrays.
• Ghosts are demonstrated to be equivalent to direct target images from alternative observation angles.
• A performance gain of up to 32% in target classification was achieved by exploiting ghosts.

Conclusions:

• Multipath ghosts can be mathematically characterized and localized using a defined PSF.
• The equivalence of ghosts to off-angle direct target images provides a pathway for improved target recognition.
• Exploiting radar multipath ghosts offers a significant enhancement for target classification systems.