Scattering Simulation and Reconstruction of a 3-D Complex Target Using Downward-Looking Step-Frequency Radar

Numerical simulations of polarized scattering, 3-D imaging, and profile reconstruction of a complex-shaped electric-large target above a rough surface are developed. The bidirectional analytic ray tracing method is first applied to calculation of polarized scattering from volumetric target and underlying surface. By using the step-frequency radar working in downward-looking spotlight mode and moving within a 2-D circular arc aperture, a 3-D matrix of backscattering fields in both the amplitude and phase is obtained. The 3-D fast Fourier transform algorithm is adopted for uniformly resampling data, which are acquired by interpolating the collected uniformly sampling backscattering fields to quickly form a focused image. Automatic reconstruction of the target is then well demonstrated. As validation and comparison, the scattering fields are also computed and compared using widely accepted software FEKO based on physical optics. The technique of imaging and reconstruction for a 3-D complex-shaped perfect electric conductor electric-large target, such as a tank-like object, is presented.