袁航 , 罗迎 , 李开明 , 等 . 基于涡旋电磁波雷达的人体目标步态精细识别 [J ] . 兵工学报 , 2022 , 43 ( 5 ): 1167 - 1174 . DOI: 10.12382/bgxb.2021.0294 http://doi.org/10.12382/bgxb.2021.0294 基于雷达的人体目标识别技术在诸多领域有着重要的应用。涡旋电磁波中携带有轨道角动量，在运动目标回波中会引起线多普勒和角多普勒效应，可为识别提供更丰富的信息。但与线多普勒相比，角多普勒较微弱，二者难以被分离。使用多发多收模型产生线性调频涡旋电磁波，通过双模态回波干涉抑制线多普勒。利用短时傅里叶变换，获得双模态回波的线多普勒和角多普勒时频图，将时频图的幅度值输入到双通道卷积神经网络模型中，获得分类结果。仿真实验结果表明，将线多普勒和角多普勒分离，同时输入到分类模型中可以提升人体步态精细识别能力。

YUAN H , LUO Y , LI K M , et al . Fine recognition of human gait with vortex electromagnetic wave radar [J ] . Acta Armamentarii , 2022 , 43 ( 5 ): 1167 - 1174 . (in Chinese) DOI: 10.12382/bgxb.2021.0294 http://doi.org/10.12382/bgxb.2021.0294 Radar-based human target recognition technology has important applications in many fields. The vortex electromagnetic (EM) wave carries orbital angular momentum，and the target motion may cause the linear and angular Doppler effects. Vortex EM wave contains more target information，which can provide more information for identification. But the angular Doppler effect is much smaller than the linear Doppler effect，so it is difficult to separate them.A multi-transmitter and multi-receiver model is used to generate linear frequency modulation vortex electromagnetic wave，and the linear Doppler is suppressed by dual-mode echo interference. Then，the linear and angular Doppler time-frequency images of the dual-mode echo are obtained by using the short-time Fourier transform. The amplitude values of the time-frequency images are input into the dual-channel convolutional neural network model to obtain the classification results.The simulated results show that the fine recognition ability of human gait is improved by separating the linear Doppler and angular Doppler.

YAN Y , XIE G D , LAVERY M P , et al . High-capacity millimetre-wave communications with orbital angular momentum multiplexing [J ] . Nature communications , 2014 , 5 : 4876 . DOI: 10.1038/ncomms5876 http://doi.org/10.1038/ncomms5876 One property of electromagnetic waves that has been recently explored is the ability to multiplex multiple beams, such that each beam has a unique helical phase front. The amount of phase front 'twisting' indicates the orbital angular momentum state number, and beams with different orbital angular momentum are orthogonal. Such orbital angular momentum based multiplexing can potentially increase the system capacity and spectral efficiency of millimetre-wave wireless communication links with a single aperture pair by transmitting multiple coaxial data streams. Here we demonstrate a 32-Gbit s(-1) millimetre-wave link over 2.5 metres with a spectral efficiency of B16 bit s(-1) Hz(-1) using four independent orbitalangular momentum beams on each of two polarizations. All eight orbital angular momentum channels are recovered with bit-error rates below 3.8 x 10(-3). In addition, we demonstrate a millimetre-wave orbital angular momentum mode demultiplexer to demultiplex four orbital angular momentum channels with crosstalk less than -12.5 dB and show an 8-Gbit s(-1) link containing two orbital angular momentum beams on each of two polarizations.

ZHANG Z Q , XIAO Y , MA Z , et al . 6G wireless networks: Vision, requirements, architecture, and key technologies [J ] . IEEE Vehicular Technology Magazine , 2019 , 14 ( 3 ): 28 - 41 .

ZHANG W T , ZHENG S L , HUI X N , et al . Mode division multiplexing communication using microwave orbital angular momentum: an experimental study [J ] . IEEE Transactions on Wireless Communications , 2016 , 16 ( 2 ): 1308 - 1318 . DOI: 10.1109/TWC.2016.2645199 http://doi.org/10.1109/TWC.2016.2645199 http://ieeexplore.ieee.org/document/7797488/ http://ieeexplore.ieee.org/document/7797488/

THIDÉ B , THEN H , SJÖHOLM J , et al . Utilization of photon orbital angular momentum in the low-frequency radio domain [J ] . Physical Review Letters , 2007 , 99 ( 8 ): 087701 . DOI: 10.1103/PhysRevLett.99.087701 http://doi.org/10.1103/PhysRevLett.99.087701 https://link.aps.org/doi/10.1103/PhysRevLett.99.087701 https://link.aps.org/doi/10.1103/PhysRevLett.99.087701

MOHAMMADI S M , DALDORFF L K S , BERGMAN J E S , et al . Orbital angular momentum in radio-a system study [J ] . IEEE Transactions on Antennas and Propagation , 2010 , 58 ( 2 ): 565 - 72 . DOI: 10.1109/TAP.2009.2037701 http://doi.org/10.1109/TAP.2009.2037701 http://ieeexplore.ieee.org/document/5345758/ http://ieeexplore.ieee.org/document/5345758/

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.7727 http://doi.org/10.1109/LAWP.7727 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7727 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=7727

LIN M T , GAO Y , LIU P G , et al . Super-resolution orbital angular momentum based radar targets detection [J ] . Electronics Letters , 2016 , 52 ( 13 ): 1168 - 1170 . DOI: 10.1049/ell2.v52.13 http://doi.org/10.1049/ell2.v52.13 https://onlinelibrary.wiley.com/toc/1350911x/52/13 https://onlinelibrary.wiley.com/toc/1350911x/52/13

CHEN R , LONG W X , WANG X D , et al . Multi-mode OAM radio waves: generation, angle of arrival estimation and reception with UCAs [J ] . IEEE Transactions on Wireless Communications , 2020 , 19 ( 10 ): 6932 - 6947 . DOI: 10.1109/TWC.2020.3007026 http://doi.org/10.1109/TWC.2020.3007026 https://ieeexplore.ieee.org/document/9139401/ https://ieeexplore.ieee.org/document/9139401/

孙丽华 , 闫晓鹏 , 刘强 , 等 . 基于PM算法的涡旋电磁波引信超分辨测向方法 [J ] . 北京航空航天大学学报 , 2022 , 48 ( 7 ): 1263 - 1268 .

SUN L H , YAN X P , LIU Q , et al . PM based super_resolution method of azimuth detection for electromagnetic vortex wave fuze [J ] . Journal of Beijing University of Aeronautics and Astronautics , 2022 , 48 ( 7 ): 1263 - 1268 . (in Chinese)

OMAR A . Dependence of beamforming on the excitation of orbital angular momentum modes [J ] . IEEE Transactions on Antennas and Propagation , 2020 , 68 ( 10 ): 7039 - 7045 . DOI: 10.1109/TAP.8 http://doi.org/10.1109/TAP.8 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=8 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=8

SHEN F , MU J N , GUO K , et al . Generating circularly polarized vortex electromagnetic waves by the conical conformal patch antenna [J ] . IEEE Transactions on Antennas and Propagation , 2019 , 67 ( 9 ): 5763 - 5771 . DOI: 10.1109/TAP.8 http://doi.org/10.1109/TAP.8 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=8 https://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=8

GAO X F , LI P , HAO X H , et al . A novel DOA estimation algorithm using directional antennas in cylindrical conformal arrays [J ] . Defence Technology , 2021 , 17 ( 3 ): 1042 - 1051 . DOI: 10.1016/j.dt.2020.06.010 http://doi.org/10.1016/j.dt.2020.06.010 In this paper, a novel direction of arrival (DOA) estimation algorithm using directional antennas in cylindrical conformal arrays (CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subarrays to obtain the complete output vector. Considering the anisotropic radiation pattern of a CCA, which cannot be separated from the manifold matrix, an improved interpolation method is investigated to transform the directional subarray into omnidirectional virtual nested arrays without non-orthogonal perturbation on the noise vector. Then, the cross-correlation matrix (CCM) of the subarrays is used to generate the consecutive co-arrays without redundant elements and eliminate the noise vector. Finally, the full-rank equivalent covariance matrix is constructed using the output of co-arrays, and the unitary estimation of the signal parameters via rotational invariance techniques (ESPRIT) is performed on the equivalent covariance matrix to estimate the DOAs with low computational complexity. Numerical simulations verify the superior performance of the proposed algorithm, especially under a low signal-to-noise ratio (SNR) environment. © 2020 The Authors

GOOSSENS R , ROGIER H . A hybrid UCA-RARE/Root-MUSIC approach for 2-D direction of arrival estimation in uniform circular arrays in the presence of mutual coupling [J ] . IEEE Transactions on Antennas and Propagation , 2007 , 55 ( 3 ): 841 - 849 . DOI: 10.1109/TAP.2007.891848 http://doi.org/10.1109/TAP.2007.891848 http://ieeexplore.ieee.org/document/4120259/ http://ieeexplore.ieee.org/document/4120259/

HUANG Z Y , BALANIS C A , BIRTCHER C R . Mutual coupling compensation in UCAs:simulations and experiment [J ] . IEEE Transactions on Antennas & Propagation , 2006 , 54 ( 11 ): 3082 - 3086 .

WANG B H , HUI H T , LEONG M S . Decoupled 2D direction of arrival estimation using compact uniform circular arrays in the presence of elevation-dependent mutual coupling [J ] . IEEE Transactions on Antennas and Propagation , 2010 , 58 ( 3 ): 747 - 755 . DOI: 10.1109/TAP.2009.2039323 http://doi.org/10.1109/TAP.2009.2039323 http://ieeexplore.ieee.org/document/5371884/ http://ieeexplore.ieee.org/document/5371884/

LIN M , YANG L . Blind calibration and DOA estimation with uniform circular arrays in the presence of mutual coupling [J ] . IEEE Antennas and Wireless Propagation Letters , 2006 , 5 : 315 - 318 . DOI: 10.1109/LAWP.2006.878898 http://doi.org/10.1109/LAWP.2006.878898 http://ieeexplore.ieee.org/document/1661928/ http://ieeexplore.ieee.org/document/1661928/

李磊 , 李国林 . 一种新的相干信源互耦自校正算法 [J ] . 北京理工大学学报 , 2016 , 36 ( 12 ): 1303 - 1308 .

LI L , LI G L . A novel self-calibration algorithm for coherent signal sources [J ] . Transactions of Beijing Institute of Technology , 2016 , 36 ( 12 ): 1303 - 1308 . (in Chinese)

MATHEWS C P , ZOLTOWSKI , et al . Eigenstructure techniques for 2-D angle estimation with uniform circular arrays [J ] . IEEE Transactions on Signal Processing , 1994 , 42 ( 9 ): 2395 - 2407 . DOI: 10.1109/78.317861 http://doi.org/10.1109/78.317861 http://ieeexplore.ieee.org/document/317861/ http://ieeexplore.ieee.org/document/317861/

潘曦 , 佟颖 , 王华阳 . 球谐域传播算子快速声定向算法 [J ] . 兵工学报 , 2018 , 39 ( 10 ): 1936 - 1944 . DOI: 10.3969/j.issn.1000-1093.2018.10.008 http://doi.org/10.3969/j.issn.1000-1093.2018.10.008 为了在低信噪比情况下宽带声源可以获得较好的波达方向（DOA)估计并且降低运算量，将正交传播算子算法推广应用于球谐域。在建立球阵列声场模型基础上，提出两种基于球谐传播算子定向算法，即使用球傅里叶变换成分获得传播算子的算法和使用球傅里叶变换成分的交叉谱矩阵获得传播算子的算法。分析了不同半径的球阵列频率适应范围，解决了宽带声源频率适应性问题；比较分析了上述两种算法和球谐域多重信号分类算法在不同信噪比下的DOA估计性能，进行声源定向实验并测试3种算法的DOA估计用时。实验结果表明，两种算法均具有运算量小、花费时间少且定向准确的特点。

PAN X , TONG Y , WANG H Y . Acoustic sources localization using propagator method in spherical harmonic domain [J ] . Acta Armamentarii , 2018 , 39 ( 10 ): 1936 - 1944 . (in Chinese) DOI: 10.3969/j.issn.1000-1093.2018.10.008 http://doi.org/10.3969/j.issn.1000-1093.2018.10.008 In order to obtain the better direction of arrival (DOA) estimation and reduce the amount of computation for the wideband acoustic source under the condition of low signal-to-noise ratio, the ortho- gonal propagator algorithm is now applied to the spherical harmonic domain. Based on the establishment of a spherical array acoustic field model, two spherical harmonic propagator orientation algorithms are proposed, including the algorithm in which the spherical Fourier transform component is used to obtain the propagator and the algorithm in which the cross spectrum matrix with the spherical Fourier transform component is used to obtain the propagator. The frequency adaptation range of spherical arrays with different radii is analyzed, and the problem of multi-bandwidth acoustic source frequency adaptability is solved. The DOA estimation performances of the two algorithms and the spherical harmonic domain multiple signal classification algorithm under different SNRs are compared and analyzed. Acoustic source orientation experiments were performed, and the DOA estimation time of the three algorithms was test. Experiments show that both algorithms have the characteristics of small computation, less time and accurate orientation. Key

PFEIFFER C , DAGEFU F , TOMASIC B , et al . Virtual impedance method for mutual coupling compensation [J ] . IEEE Transactions on Antennas and Propagation , 2021 , 69 ( 8 ): 4569 - 4579 . DOI: 10.1109/TAP.2021.3060129 http://doi.org/10.1109/TAP.2021.3060129 https://ieeexplore.ieee.org/document/9362149/ https://ieeexplore.ieee.org/document/9362149/

SCHMIDT R . Multiple emitter location and signal parameter estimation [J ] . IEEE transactions on antennas and propagation , 1986 , 34 ( 3 ): 276 - 280 . DOI: 10.1109/TAP.1986.1143830 http://doi.org/10.1109/TAP.1986.1143830 https://ieeexplore.ieee.org/document/1143830/ https://ieeexplore.ieee.org/document/1143830/

LI J F , ZHANG X F , CHEN H . Improved two-dimensional DOA estimation algorithm for two-parallel uniform linear arrays using propagator method [J ] . Signal Processing , 2012 , 92 ( 12 ): 3032 - 3038 . DOI: 10.1016/j.sigpro.2012.06.010 http://doi.org/10.1016/j.sigpro.2012.06.010 https://linkinghub.elsevier.com/retrieve/pii/S0165168412002010 https://linkinghub.elsevier.com/retrieve/pii/S0165168412002010

GALUÉ L . A generalized Bessel function [J ] . Integral Transforms and Special Functions , 2003 , 14 ( 5 ): 395 - 401 . DOI: 10.1080/1065246031000074362 http://doi.org/10.1080/1065246031000074362 http://www.tandfonline.com/doi/abs/10.1080/1065246031000074362 http://www.tandfonline.com/doi/abs/10.1080/1065246031000074362

POZAR D M . A relation between the active input impedance and the active element pattern of a phased array [J ] . IEEE Transactions on Antennas and Propagation , 2003 , 51 ( 9 ): 2486 - 2489 . DOI: 10.1109/TAP.2003.816302 http://doi.org/10.1109/TAP.2003.816302 http://ieeexplore.ieee.org/document/1229923/ http://ieeexplore.ieee.org/document/1229923/

STOICA P , LARSSON E G , GERSHMAN A B . The stochastic CRB for array processing: a textbook derivation [J ] . IEEE Signal Processing Letters , 2001 , 8 ( 5 ): 148 - 150 . DOI: 10.1109/97.917699 http://doi.org/10.1109/97.917699 http://ieeexplore.ieee.org/document/917699/ http://ieeexplore.ieee.org/document/917699/