Imaging and reconstruction of a 3D complex target using downward-looking step-frequency radar

A technique of imaging and reconstruction for a three-dimensional (3D) complex-shaped Perfect Electric Conductor (PEC) target is developed using step-frequency radar observation synthesizing a two-dimensional aperture. The radar works in downward-looking spotlight mode moving within a 2D circular arc aperture to eliminate geometric disortions and shadowing effect, and the backscattered electrical fields in both the amplitude and phase are obtained. The three-dimensional fast Fourier transform (3D-FFT) algorithm is adopted for uniformly resampling data, which are aquired by interpolating the collected backscattering fields to quickly form a focus image. The bidirectional analytic ray tracing (BART) method [1] is applied to fast calculate the backscattering fields from the 3D complex target, e.g. a tank. Automatic reconstruction of the target is well demonstrated. As a validation, the scattering fields are also computed and compared using widely accepted software FEKO based on Physical Optics.