3-D Imaging by hierarchical disaggregation

A new accelerated method for generating a fully polarimetric 3-D image of an arbitrary current distribution is proposed. The sampled farfield radiation pattern is sufficient for the reconstruction of the image. The algorithm is based on a coherent summation of the fully polarimetric plane wave spectrum. The processing of the spectrum is accelerated by a Multi-Level Fast Multipole Method-inspired hierarchical disaggregation. Therefore, the complexity of the algorithm is only O(NlogN), where N refers to the number of field samples. This complexity is identical to that of FFT accelerated 3-D inverse synthetic aperture radar imaging (ISAR) techniques. But in contrast to these techniques, our approach does not require Cartesian reformatting of the plane wave spectrum and can therefore be neatly combined with Nearfield-Farfield-Transformation to provide nearfield imaging.