High-resolution Radar Imaging Using Two-dimensional Superresolution Techniques

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Radar imaging is an important technique to identify a radar target . Resolution is, however, limited because the two-dimensional Fourier transform has been employed. The purpose of this study is to establish a method whichgives high-resolution radar imaging, and to develop related techniques. Major results obtained in the research period are as follws :1.A superresolution technique using a two-dimensional MUSIC algorithm was developed for the radar imaging . It has high-resolution capabilities.2.The two-dimensional MUSIC is not reliable when there are many signals. We introduced spatial-domain gating which bounds a region to reduce the number of signals. The gating is applied before we use the MUSIC method.3.In order to examine the high-resolution capabilities of the two-dimensional MUSIC,we carried out indoor radio propagation experiments. We measure an amplitude and phase of an unmodulated sinusoidal wave in a stepped frequency system. We repeat this measurement at different receiving antenna positions. It was shown that estimation of the arrival angle and propagation time of each multipath component is equivalent to that of each scattering center in the radar imaging. From the experiments, it was shown that the two-dimensional MUSIC algorithm can resolve two close located signals which the conventional Fourier technique cannot resolve.4.The MUSIC algorithm works properly when scattering centers do not have frequency dependence. We modified the MUSIC method in such a way that it can be applied to signals with amplitude frequency dependence. These considerations will be useful for high-resolution estimation of a radar target including frequency dependent scattering centers .