Precision Near-Field Reconstruction in the Time Domain via Minimum Entropy for Ultra-High Resolution Radar ImagingReportar como inadecuado


Precision Near-Field Reconstruction in the Time Domain via Minimum Entropy for Ultra-High Resolution Radar Imaging


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School of Integrated Technology, Yonsei Institute of Convergence Technology YICT, Yonsei University, Incheon 21983, Korea





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Academic Editors: Francesco Soldovieri, Raffaele Persico, Zhong Lu and Prasad S. Thenkabail

Abstract Ultra-high resolution UHR radar imaging is used to analyze the internal structure of objects and to identify and classify their shapes based on ultra-wideband UWB signals using a vector network analyzer VNA. However, radar-based imaging is limited by microwave propagation effects, wave scattering, and transmit power, thus the received signals are inevitably weak and noisy. To overcome this problem, the radar may be operated in the near-field. The focusing of UHR radar signals over a close distance requires precise geometry in order to accommodate the spherical waves. In this paper, a geometric estimation and compensation method that is based on the minimum entropy of radar images with sub-centimeter resolution is proposed and implemented. Inverse synthetic aperture radar ISAR imaging is used because it is applicable to several fields, including medical- and security-related applications, and high quality images of various targets have been produced to verify the proposed method. For ISAR in the near-field, the compensation for the time delay depends on the distance from the center of rotation and the internal RF circuits and cables. Required parameters for the delay compensation algorithm that can be used to minimize the entropy of the radar images are determined so that acceptable results can be achieved. The processing speed can be enhanced by performing the calculations in the time domain without the phase values, which are removed after upsampling. For comparison, the parameters are also estimated by performing random sampling in the data set. Although the reduced data set contained only 5% of the observed angles, the parameter optimization method is shown to operate correctly. View Full-Text

Keywords: inverse synthetic aperture radar ISAR; minimum entropy; near-field; radar imaging; close–range; time domain; ultra-high resolution UHR; ultra-wideband UWB; vector network analyzer VNA inverse synthetic aperture radar ISAR; minimum entropy; near-field; radar imaging; close–range; time domain; ultra-high resolution UHR; ultra-wideband UWB; vector network analyzer VNA





Autor: Jiwoong Yu and Min-Ho Ka *

Fuente: http://mdpi.com/



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