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The one-dimensional (1D) range profile is an important back scattering characteristic of objective, which reveals the longitudinal distribution of radar cross section (RCS) along the detection beam. Since the shape and posture can be reflected by the 1D range profile, it is of great significance in military to determine the target orientation, velocity and whether it is armed. In this paper, broadband terahertz 1D-range-profile measurement system is built based on the time-domain spectroscopy (TDS) system. It is in bistatic configuration (bistatic angle of 9°) and the signal-to-noise ratio (SNR) is 34.5 dB, with a gold mirror used as a reflector. Benefiting from the ultrashort terahertz pulse width (full pulse width of 0.52 ps), the bandwidth covers the frequency range from 0.1 THz to 2.5 THz (peaked at 0.9 THz), corresponding to the range resolution on a submillimeter scale. Firstly, the 1D range profiles of several objects in different shapes are measured, including the step, cylinder, step cone and their combination, which indicates that the geometric profile of the target in the detection direction is adequate to identify the shape feature of the target and proves the reliability of the 1D range profile measuring system based on TDS. Secondly, aluminum plates with different surface roughness in a range of 0–25 μm are also characterized. The Kirchhoff approximation theory and small perturbation method (SPM) are introduced to illustrate the characteristics of broadband terahertz 1D range profile related to the surface roughness of target. It is found that the scattering characteristic of metal object in the terahertz range is sensitive to surface roughness. If the surface roughness of the object is larger, the peak intensity of the 1D range profile will be weaker and the echo signal pulse width becomes wider. The rule is also applicable for the cases with different incident angles. Furthermore, it is revealed that the time delay of the 1D range profile in the bistatic system is related to the rotation direction of the target, which is useful in estimating the posture of the target. In summary, the characteristics of 1D range profile for metal objects relating to shape, surface roughness and posture are studied. The conclusions have certain guiding significance for the target detection and recognition of terahertz radar. -
Keywords:
- terahertz radar /
- rough surface scattering characteristic /
- terahertz time-domain spectroscopy system /
- one-dimensional range profile
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Guo L X, Wang R, Wu Z S 2010 Basic Theories and Methods of Random Rough Surface Scattering (Beijing: Science Press) p47
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图 1 宽带太赫兹一维距离像测量系统
Figure 1. Measurement system of broadband terahertz one-dimensional (1D) range profiles.
图 2 金镜反射信号 (a) 时域; (b) 频域
Figure 2. Reflected signal of gold mirror: (a) Time domain; (b) frequency domain.
图 3 阶梯目标一维距离像 (a) 时域; (b) 频域
Figure 3. 1D range profile of step: (a) Time domain; (b) frequency domain.
图 4 不同形状简单体目标及其组合的一维距离像 (a) 圆柱; (b) 台阶体; (c) 组合体; (d) 阶梯圆锥
Figure 4. 1D range profiles of different simple objects and their combination: (a) Cylinder; (b) step; (c) combination; (d) step cone.
图 5 不同粗糙度铝合金平板的一维距离像实验与基尔霍夫近似理论对比结果. 其中理论计算中选取太赫兹频率为0.9 THz, 光滑铝合金表面反射率设为0.995
Figure 5. Comparison of 1D range profile experimental results with Kirchhoff approximation theoretical results of Al plates with different surface roughness. The terahertz frequency is 0.9 THz and reflectance of smooth Al surface is 0.995 in theoretical calculation.
图 6 实验测得的不同粗糙度铝板一维像脉宽展宽与入射角度的关系
Figure 6. Relationship between 1D profiles pulse widths of Al plates with different surface roughness and the incident angle.
图 7 不同粗糙程度铝质表面后向散射系数与入射角度的关系
Figure 7. Relationship between back scattering coefficient of Al surfaces with different roughness and the incident angle.
图 8 目标平板旋转示意图
Figure 8. Schematic of objects rotation.
图 9 粗糙度为7 μm的粗糙铝合金平板在不同转角下的一维距离像. 其中, “–”代表顺时针, “+”代表逆时针
Figure 9. 1D range profiles of Al plate with roughness of 7 μm at different incident angle. “–” means clockwise, “+” means anticlockwise.
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[1] Beard M C, Turner G M, Schmuttenmaer C A 2002 J. Phys. Chem. B 106 7146
Google Scholar
[2] Lee S, Baek S, Kim T T, Cho H, Lee S, Kang J H, Min B 2020 Adv. Mater. 32 2000250
Google Scholar
[3] Naftaly M, Miles R E 2007 Proc. IEEE 95 1658
Google Scholar
[4] Sheen D M, Fernandes J L, Tedeschi J R, McMakin D L, Jones A M, Lechelt W M, Severtsen R H 2013 Proc. SPIE 8715 871509
[5] 江月松, 聂梦瑶, 张崇辉, 辛灿伟, 华厚强2015 64 024101
Google Scholar
Jiang Y S, Nie M Y, Zhang C H, Xin C W, Hua H Q 2015 Acta Phys. Sin. 64 024101
Google Scholar
[6] 梁达川, 魏明贵, 谷建强, 尹治平, 欧阳春梅, 田震, 何明霞, 韩家广, 张伟力 2014 63 214102
Google Scholar
Liang D C, Wei M G, Gu J Q, Yin Z P, Ouyang C M, Tian Z, He M X, Han J G, Zhang W L 2014 Acta Phys. Sin. 63 214102
Google Scholar
[7] Jansen C, Krumbholz N, Geise R, Enders A, Koch M 2009 3rd European Conference on Antennas and Propagation Berlin, Germany, March 23–27, 2009 p3645
[8] Brooks L D, Wolfe W L 1980 Proc. SPIE 257 177
Google Scholar
[9] Cheville R A, Daniel R G 1995 Appl. Phys. Lett. 67 1960
Google Scholar
[10] Gente R, Jansen C, Geise R, Peters O, Gente M, Krumbholz N, Moller C, Busch S F, Koch M 2012 IEEE Trans. Terahertz Sci. Technol. 2 424
Google Scholar
[11] 王瑞君 2015 博士学位论文 (长沙: 国防科学技术大学)
Wang R H 2015 Ph. D. Dissertation (Changsha: National University of Defense Technology
[12] Li Y, Tong L, Yang X, Li M 2018 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) Valencia, Spain, July 22–27, 2018 p2131
[13] Li J, Guo L X, Zeng H 2008 Prog. Electromagn. Res. 88 197
Google Scholar
[14] Jiang D, Xu X J 2010 International Conference on Electromagnetics in Advanced Applications Sydney, Australia, September 20–24, 2010 p847
[15] Erich N G, Nina P, Richard A C, Joshua G, David N 2017 IEEE Trans. Terahertz Sci. Technol. 7 546
Google Scholar
[16] Dikmelik Y, Spicer J B, Fitch M J, Osiander R 2006 Opt. Lett. 31 3653
Google Scholar
[17] DiGiovanni D A, Gatesman A J, Goyette T M, Giles R H 2014 Proc. SPIE 9078 90780A
[18] Wei J C, Chen H, Qin X, Cui T J, 2017 IEEE Trans. Antennas Propag. 65 3154
Google Scholar
[19] Gao J K, Wang R J, Deng B, Qin Y L, Wang H Q, Li X 2017 IEEE Antennas Wirel. Propag. Lett. 16 975
Google Scholar
[20] 牟媛, 吴振森, 赵豪, 武光玲 2018雷达学报7 83
Google Scholar
Mou Y, Wu Z S, Zhao H, Wu G L 2018 J. Radars 7 83
Google Scholar
[21] 陈刚, 党红杏, 谭小敏, 陈珲, 崔铁军 2018 雷达学报7 75
Google Scholar
Chen G, Dang H X, Tan X M, Chen H, Cui T J 2018 J. Radars 7 75
Google Scholar
[22] Jun C W, Chen H, Cui T J 2016 Geoscience and Remote Sensing Symposium Beijing, China, July 10–15, 2016 p3680
[23] 史杰, 钟凯, 刘楚, 王茂榕, 乔鸿展, 李吉宁, 徐德刚, 姚建铨 2018 红外与激光工程 47 194
Shi J, Zhong K, Liu C, Wang M R, Qiao H Z, Li J N, Xu D G, Yao J Q 2018 Infrared Laser Eng. 47 194
[24] 欧湛, 郑小平, 耿华 2019 清华大学学报(自然科学版) 59 388
Google Scholar
Ou Z, Zheng X P, Geng H 2019 J. Tsinghua Univ. (Sci. Technol. ) 59 388
Google Scholar
[25] Bennett H E, Porteus J O 1961 J. Opt. Soc. Am. 51 123
Google Scholar
[26] 郭立新, 王蕊, 吴振森 2010 随机粗糙面散射的基本理论与方法 (北京: 科学出版社) 第47页
Guo L X, Wang R, Wu Z S 2010 Basic Theories and Methods of Random Rough Surface Scattering (Beijing: Science Press) p47
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