3-D Near-Field Passive Radar Imaging Using Multiple Illumination Sources

A team of researchers has published a paper detailing a significant advance in passive radar imaging. The technique, developed by Quanfeng Wang, Mei Song Tong, and Thomas F. Eibert, focuses on 3D near-field imaging that relies on illumination from non-cooperative transmitters, like existing radio or TV towers. The core innovation is using multiple transmitters at different locations instead of a single source. This multi-perspective approach ensures that complex targets, particularly those with concave shapes like dihedral corners, are illuminated from various angles, dramatically reducing blind spots that plague single-source systems.

For each transmitter configuration, the team uses a single-frequency inverse source solver to reconstruct the target's equivalent sources. The individual images from each source are then superimposed coherently using phase and magnitude correction methods. This coherent summation is key, as it actively suppresses configuration-dependent artifacts and 'ghost' images caused by multiple reflections. Finally, multi-frequency images are combined to further enhance overall quality. The paper, which has been accepted for a major 2025 IEEE conference, presents both simulation and physical measurement results that validate the method's effectiveness in producing clearer, more reliable 3D images without needing to control the illuminating signal source.