Three dimensional SAR imaging based on the focused electromagnetic vortex beam
-
摘要: 合成孔径雷达(synthetic aperture radar, SAR)能够突破天线孔径对分辨率的限制,因而得到了广泛应用. 本文提出了一种基于聚合型涡旋电磁波束的三维SAR成像方法,通过设计合适的成像几何构型,利用涡旋电磁波的相位特性实现对高度维的分辨,并推导得到高度维分辨率与模式数及雷达参数之间的关系. 考虑到回波信号中引入的涡旋相位项,对后向投影算法进行改进,实现对观测区域的三维成像,并引入稀疏重构算法减少对模式数的需求. 仿真结果表明,利用多模式聚合型涡旋电磁波束能够对分布在不同高度的目标进行准确重构,利用稀疏重构算法能够用少数模式实现高分辨三维成像. 本文提出的方法为新体制雷达成像研究提供了一定的参考.
-
关键词:
- 合成孔径雷达(SAR) /
- 涡旋电磁波 /
- 三维成像 /
- 后向投影 /
- 稀疏重构
Abstract: Synthetic aperture radar(SAR) is widely applied since it can break through the limitation of resolution by antenna aperture. In this paper, the focused electromagnetic(EM) vortex beam is applied to synthetic aperture radar to realize 3D imaging. By appropriately designing the imaging geometry, height resolution can be achieved with the use of the phase characteristics of EM vortex wave, and the relationship between height resolution and the number of orbital angular momentum(OAM) mode and radar parameters is derived. Considering the vortex phase term introduced in the echo signal, the improved back projection algorithm is applied to realize 3D imaging, and then sparse recovery algorithm is introduced to reduce the demand of the number of OAM mode. Simulation results indicate that the targets distributed at different heights can be accurately reconstructed, and high resolution is realized by sparse recovery method with few OAM modes. The method in this paper provides a certain reference for the research of new radar imaging system. -
表 1 仿真参数
Tab. 1 Simulation parameters
参数 取值 载体平台高度H 1 000 m 速度v 150 m/s 中心频率fc 5 GHz 带宽B 50 MHz 脉冲宽度T 2.5 μs 调频率Kr 20×1012 Hz/s 天线半径r 1 m 入射角β 45° 表 2 12个点目标位置
Tab. 2 locations of the 12 points
点目标 位置/m 点目标 位置/m P1 (1 020,−10,0) P7 (1 020,10,50) P2 (1 040,−10,0) P8 (1 040,10,50) P3 (1 020,10,0) P9 (1 020,−10,100) P4 (1 040,10,0) P10 (1 040,−10,100) P5 (1 020,−10,50) P11 (1 020,10,100) P6 (1 040,−10,50) P12 (1 040,10,100) -
[1] ALLEN L, BEIJERSBERGEN M W, SPREEUW R J, et al. Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes[J]. Physical review A,1992,45(11):8185-8189. DOI: 10.1103/PhysRevA.45.8185 [2] MOHAMMADI S M, DALDORFF L K S, BERGMAN J E S, et al. Orbital angular momentum in radio system study[J]. IEEE transactions on antennas and propagation,2009,58(2):565-572. [3] MOHAMMADI S M, DALDORFF L K S, FOROZESH K, et al. Orbital angular momentum in radio: measurement methods[J]. Radio science,2010,45(4):1-14. [4] YANG Y W, CHENG W C, ZHANG W, et al. Mode modulation for wireless communications with a twist[J]. IEEE transactions on vehicular technology,2018,67(11):10704-10714. DOI: 10.1109/TVT.2018.2867566 [5] ALLEN B, TENNANT A, BAI Q, et al. Wireless data encoding and decoding using OAM modes[J]. Electronics letters,2014,50(3):232-233. DOI: 10.1049/el.2013.3906 [6] TAMBURINI F, MARI E, SPONSELLI A, et al. Encoding many channels in the same frequency through radio vorticity: first experimental test[J]. New journal of physics,2011,14(3):811-815. [7] 郭桂蓉, 胡卫东, 杜小勇. 基于电磁涡旋的雷达目标成像[J]. 国防科技大学学报,2013,35(6):71-76. DOI: 10.3969/j.issn.1001-2486.2013.06.013GUO G R, HU W D, DU X Y. Electromagnetic vortex based radar target imaging[J]. Journal of national university of defense technology,2013,35(6):71-76. (in Chinese) DOI: 10.3969/j.issn.1001-2486.2013.06.013 [8] LIU K, CHENG Y Q, YANG Z C, et al. Orbital-angular momentum-based electromagnetic vortex imaging[J]. IEEE antennas and wireless propagation letters,2015,14:711-714. DOI: 10.1109/LAWP.2014.2376970 [9] LIU K, LIU H Y, QIN Y L, et al. Generation of OAM beams using phased array in the microwave band[J]. IEEE transactions on antennas and propagation,2016,64(9):3850-3857. DOI: 10.1109/TAP.2016.2589960 [10] YUAN T Z, WANG H Q, QIN Y L, et al. Electromagnetic vortex imaging using uniform concentric circular arrays[J]. IEEE antennas and wireless propagation letters,2016,15:1024-1027. DOI: 10.1109/LAWP.2015.2490169 [11] ZHANG C, CHEN D, JIANG X F. RCS diversity of electromagnetic wave carrying orbital angular momentum[J]. Scientific reports,2017,7:15412. DOI: 10.1038/s41598-017-15250-7 [12] YU M P, HAN Y P, CUI Z W. Scattering of non-diffracting vortex electromagnetic wave by typical targets[J]. Progress in electromagnetics research letters,2017,70:139-146. DOI: 10.2528/PIERL17060504 [13] RANEY R K, RUNGE H, BAMLER R, et al. Precision SAR processing using chirp scaling[J]. IEEE transactions on geoscience and remote sensing,1994,32(4):786-799. DOI: 10.1109/36.298008 [14] CUMMING I G, WONG F H. Digital processing of synthetic aperture radar data: algorithms and implementation[M]. Norwood: Artech House, 2005. [15] REIGBER A, MOREIRA A. First demonstration of airborne SAR tomography using multibaseline L-band data[J]. IEEE transactions on geoscience and remote sensing,2000,38(5):2142-2152. DOI: 10.1109/36.868873 [16] NANNINI M, SCHEIBER R, HORN R, et al. First 3-D reconstructions of targets hidden beneath foliage by means of polarimetric SAR tomography[J]. IEEE geoscience and remote sensing letters,2012,9(1):60-64. DOI: 10.1109/LGRS.2011.2160329 [17] 方越, 王鹏波, 陈杰. 基于轨道角动量的电磁涡旋SAR成像新方法[J]. 上海航天,2018,35(6):11-14.FANG Y, WANG P B, CHEN J. A novel imaging algorithm for electromagnetic vortex SAR based on orbital angular momentum[J]. Aerospace shanghai,2018,35(6):11-14. (in Chinese) [18] 杜永兴, 仝宗俊, 秦岭, 等. 基于改进BP算法的电磁涡旋成像方法[J]. 雷达科学与技术,2020,18(5):83-89.DU Y X, TONG Z J, QIN L, et al. Electromagnetic vortex imaging method based on improved BP algorithm[J]. Radar science and technology,2020,18(5):83-89. (in Chinese) [19] WANG J Q, LIU K, WANG H Q. Side-looking stripmap SAR based on vortex electromagnetic waves[C]//IEEE International Conference on Communications Workshops, Shanghai, May, 2019. [20] WANG J Q, LIU K, CHENG Y Q, et al. Three-dimensional target imaging based on vortex stripmap SAR[J]. IEEE sensors journal,2019,19(4):1338-1345. DOI: 10.1109/JSEN.2018.2879814 [21] BU X X, ZHANG Z, CHEN L Y, et al. Implementation of vortex electromagnetic waves high-resolution synthetic aperture radar imaging[J]. IEEE antennas and wireless propagation letters,2018,17(5):764-767. DOI: 10.1109/LAWP.2018.2814980 [22] ZHANG Z F, ZHENG S L, JIN X F, et al. Generation of plane spiral OAM waves using traveling-wave circular slot antenna[J]. IEEE antennas and wireless propagation letters,2017,16:8-11. DOI: 10.1109/LAWP.2016.2552227 [23] ZHENG S L, CHEN Y L, ZHANG Z F, et al. Realization of beam steering based on plane spiral orbital angular momentum wave[J]. IEEE transactions on antennas and propagation,2018,66(3):1352-1358. DOI: 10.1109/TAP.2017.2786297 [24] GOKLANI H S, SARVAIYA J N, FAHAD A M. Image reconstruction using Orthogonal Matching Pursuit (OMP) algorithm[C]//The 2nd International Conference on Emerging Technology Trends in Electronics, Communication and Networking, Surat, 2014: 1-5. -