首页 >  , Vol. , Issue () : 1993-2002

摘要

引用本文:

DOI:

收稿日期:

2019-03-19

修改日期:

2019-05-14

PDF Free   EndNote   BibTeX
受随机介质遮蔽目标的雷达成像方法效能比较
伊铁延, 陈锟山, 刘玉
中科院空天信息研究院
摘要:

为了综合分析受随机介质遮蔽目标雷达成像方法效能,本文系统比较了随机介质参数(散射厚度与吸收厚度)、天线布局方式(稀疏阵列的天线阵元间距及空间分布)对合成孔径雷达SAR、时间反转TR以及时间反转-多重信号分类TR-MUSIC这三种典型方法成像效能的影响。结果表明TR-MUSIC表现最优,SAR次之,TR较弱。随着光学厚度或单次散射反照率的增大,三种成像方法效能均发生退化,但TR-MUSIC总体而言相对受影响最弱。散射厚度是造成成像效能退化的主要原因,而吸收厚度的影响较为微弱。根据稀疏阵列下成像方法效能比较结果,利用TR-MUSIC可以抑制栅瓣特性的优势,使用特殊布局的天线可以同时降低雷达系统复杂度和减弱杂波信号,进而改善成像结果。本研究可为提高受随机介质遮蔽目标的雷达成像质量提供理论支撑。

A Comparative Study of Radar Imaging of the Target Obscured by Random Media
Abstract:

Radar imaging of objects obscured by random media is an important issue for its wide use in the fields of geography, medicine, and the military. However, due to the presence of random media (vegetation, atmospheric turbulence, biological tissues or walls), the echo signals from the observed target(s) may be severely distorted, eventually leading to the degradation of imaging quality. In order to obtain higher resolution, imaging technology working in the millimeter wave or even higher frequency band is desirable. However, the electromagnetic wave in this frequency band is more heavily affected by random media and more susceptible to attenuation, which hinders the application of millimeter wave radar remote sensing. This limitation further highlights the urgency of research on imaging of objects obscured by random media. Therefore, it is especially important to fully evaluate the imaging performance and ultimately improve it. Synthetic Aperture Radar (SAR) technology has been widely used in many fields, especially for remote sensing, since its introduction in the 1950s. Scholars have proposed a variety of imaging algorithms and used the obtained data to analyze the dielectric properties and geometric characteristics of the observed target (INSAR, POL-SAR, POL-INSAR and TOMO-SAR). Alternatively, some imaging technology employs the time symmetry of the field (electromagnetic or acoustics) wave equation and the reciprocity of the Green’s function to locate and imaging the targets. In particular, the time reversal (TR) method allows us to selectively focus on different targets separately, while the time reversal-multiple signal classification (TR-MUSIC) method greatly improves the imaging resolution. However, current studies are often limited to a specific field, and research on comparing of the performance of different methods is relatively rare. Therefore, in this paper, we select these typical radar imaging methods to evaluate their performance about imaging the target obscured by random media. Since the target is obscured by the random media, it is necessary to describe the effects caused by random media on propagation process of the electromagnetic wave. According to the radiation transfer equation, the attenuation of electromagnetic waves caused by random medium is related to the optical thickness, which is equal to the sum of the scattering thickness and the absorption thickness. We will use the model to describe the interaction of electromagnetic waves with random media. For quantitative evaluation, 3 dB beam-width and geometric location of a point target response are used. Though results of three methods are all degraded by the presence of random media, it could be clearly seen that TR-MUSIC performs the best, SAR is second, while TR is poorest. The effects of the scattering thickness is the main factor causing imaging degradation, while the degradation caused by absorption thickness is very weak. In summary, this is due to the clutter enhancement from random media in the case of increasing the scattering thickness, while the effects of absorption thickness are the energy of electromagnetic waves being absorbed. Among the three techniques, TR and TR-MUSIC can better suppress the grating lobes than SAR does under a sparse array, and TR-MUSIC delivers the best imaging performance. Considering the advantages of TR-MUSIC in the performance and the side lobes suppression, we focus on further improving the performance of it. Based on theoretical analysis, some centrally located array elements are removed to undermine clutters, and we obtain better imaging results for TR-MUSIC.

本文暂时没有被引用!

欢迎关注学报微信

遥感学报交流群 分享按钮