Wavenumber-space analysis and imaging algorithm based on distributed multi-channel radars

Multi-input multi-output (MIMO) radar is a newly emerging radar system. Based on the diversity of transmitted signals, this paper presents the concept of a distributed multi-channel imaging radar (DMCIR) system. In this system, a set of transmitters and receivers are sparsely located to form multiple signal-processing channels. With the application of matched filtering the orthogonal signals, the wavenumber samples are obtained to reconstruct target two-dimensional reflectivity functions. In this paper, the distribution characteristics of wavenumber observations are analyzed in detail. It is concluded that the wavenumber samples are distributed on the cross points of a set of lines and circles. Based on the distribution characteristics, a polar format algorithm is proposed. In this algorithm, the uniform wavenumber samples in a rectangle are obtained by twice one-dimensional interpolations from measurement samples, which are presented in polar format. Then the two-dimensional reflectivity function of a target is reconstructed by inverse Fourier transform. The imaging algorithm makes full use of the distribution-characteristics of wavenumber samples, and corrects the scatter migration through range cells effectively. As a result focused images of targets are obtained. Moreover, this algorithm has a high image extraction efficiency, since a Fourier transform can be applied. Finally, the simulations demonstrate the performance of the imaging algorithm.