Fourier Based 3D ISAR Near-Field Imaging and Radar Cross Section Transformation

For a linear near-field scattering scenario with two antennas, a general relation between transmitter and receiver is presented, which is based on a plane-wave expansion of the Green's function. It is used to derive an expression for the case of a monostatic measurement setup, allowing to compute the far-field radar cross section from near-field measurement samples. By choosing an example with multiple reflections at the scatterer, the algorithm is validated and it is investigated how the 3D spatial reflectivity distribution can be reconstructed using Fourier transform techniques. It turns out that multiple interactions limit the accuracy of the far-field prediction but hardly effect the spatial image.