Multi-band Synthetic Radar Imaging Technology

High-resolution imaging has been pursued in radar imaging. In order to obtain higher resolution of the target's image, we need to take range-dimension and azimuth-dimension into considerations. We can increase coherent accumulation angle to obtain high azimuth-dimension resolution. Also we can increase the bandwidth of the transmitted signals to improve range-dimension resolution. This paper discusses ways to improve range resolution.We can improve the range resolution by increasing the transmitted signal's bandwidth, and the case is feasible when the bandwidth is not too high. But with the increasingly high demand for the target's resolution, generation of ultra-bandwidth signal encountered many difficulties, including technical and methodological difficulties. So we have to find another ways to generate ultra-bandwidth signals. We propose a method called multi-band fusion.Multi-band fusion which is to fuse different frequency bands efficiently will make the fused signal's bandwidth much bigger than the original signal's and the information of the original signals is also included in the new fused signals. We can obtain ultra-bandwidth signal through the fusion of multi-band. After the multi-band fusion processing, multi-band signals is stitched together in both frequency and time domain. We can obtain high range-dimension resolution by radar imaging for the fusion signals.This paper studies the characteristics of the LFM signals, the principle and characteristics of Pulse Compression, the principle and algorithms of ISAR radar imaging, as well as bandwidth fusion methods, and proposes a flow figure for radar imaging of multi-band fusion.In order to verify the effect of fused signal's radar imaging, this paper focus on the changes of resolution of LFM signal's radar imaging before and after the Pulse Compression. Compare and analyze the distance-dimension resolution through two cases which are sub-band signal and one fusion ultra-bandwidth signal. It can be seen that the signal fused by multiple signals can improve the range resolution significantly. It proves that theory of multi-band fusion process can improve the range resolution.