太赫兹雷达细微结构成像仿真与特性分析

Radar imaging simulation and characteristics analysis of the fine structure at terahertz frequencies

太赫兹频段下细微结构导体表面会对电磁散射回波的幅度、相位等产生影响。为分析这一影响,以理想导电体下尺寸可与波长比拟的周期网状结构、击芯铆钉阵列结构为例,研究了不同俯仰角电磁散射在雷达图像中的表现规律。利用卷积逆投影算法,对多角度、多频点的单站散射场回波数据进行成像。从仿真结果可以看出,不同细微结构散射特性存在明显差异。利用距离像分析方法,对不同细微结构成像结果的成因进行了分析,得出图像的不同特征可由相干相消、相干增强与虚影效应3种机理进行解释,表明太赫兹波对细微结构具有独特的刻画能力。

The fine structure of conductor surface can cause impact on the amplitude,phase of the scattered fields at THz frequencies.For analyzing these effects,periodic and reticulate structure whose dimension assimilates to wavelength,and rivets array structure with Perfect Electric Conductor(PEC)are taken as examples to illustrate the characteristics of the scattered fields of different elevation angles inradar imaging.The convolution back projection algorithm is utilized to image the multi-angles,multi-frequency monostatic scattered fields echo data generated by the commercial software platform.The simulation results show that the scattering characteristics of different fine structures differ greatly.By employing the range profile analysis method,the reasons that form different features in the image domain are obtained.It is found that the mechanism of different image features can be resorted to the effects of coherent cancellation,coherent enhancement and the virtual ghosts.These results show that the THz wave owns an unique depictive ability for the fine structure.