NUFFT-Based Algorithm for Near-field MMW Synthetic Aperture Imaging Radiometers

The near-field MMW synthetic aperture imaging radiometer is very excellent imaging system for obtaining high resolution images. The corresponding imaging algorithms are usually established based on the conventional FFT with the uniform sampling of visibility function. But a lot of irregular antenna arrays appeared for some reason, such as the coordinate perturbation and the development of the synthetic aperture imaging system. And the visibility functions of these arrays are always random. The un-Cartesian sampling data are not distributed on the uniform grid points. For this random distribution of visibility function, the traditional FFT based on the uniform Cartesian sampling cannot image well. Thus we adopt NUFFT to reconstruct the images from the non-uniform visibility function samples in this paper. Based on the near-field imaging formulas, the accurate system functions are established in NUFFT algorithm. The effectiveness of the NUFFT is tested by the corresponding simulation experiments with 1D and 2D Target scenes. The results show that the NUFFT is an effective imaging algorithm for near-field MMW synthetic aperture imaging radiometer with arbitrary distribution of the visibility function.