涡旋电磁波无线通信技术发展综述

由于携带轨道角动量(Orbital Angular Momentum,OAM),涡旋电磁波具有螺旋相位结构以及不同模态相互正交的空间性质,因此将其应用于无线通信技术领域以提升频谱利用率以及通信容量受到学界关注。介绍了涡旋电磁波的结构以及特殊性质,总结了近几年国内外涡旋电磁波在天线技术的进展并对比了各类天线性能,分析了涡旋电磁波在多输入多输出、复杂环境传输以及模态混叠检测领域的不足与发展态势,指出了未来基于涡旋电磁波无线通信发展的方向以及挑战。     

X波段下产生涡旋电磁波的阵列天线设计

随着无线通信应用的飞速发展,频谱资源日益紧张,射频频谱资源已日趋香农极限。为解决这个问题,无线通信中引入了携有轨道角动量(Orbital Angular Momentum,OAM)的涡旋电磁波,以有效提高频谱利用率。微带天线阵技术是产生涡旋电磁波常用的方法之一,以同轴馈电的矩形微带天线为阵元,设计了阵元数目分别为6,8,12的3种环形阵列天线,来产生携带有轨道角动量的涡旋电磁波。分析了不同轨道角动量模式数下,涡旋电磁波辐射能量和最大增益辐射角度变化情况。利用Ansoft HFSS仿真软件,在中心频率10 GHz处,比较了阵元数目对电磁波的涡旋特性影响。仿真结果表明,更多数量的天线阵列产生的涡旋电磁波涡旋性能更好。     

涡旋电磁波在军事无线通信中的应用

涡旋电磁波的OAM复用是一种把量子力学中的轨道角动量理论应用到无线通信领域的新型技术,拥有高效频谱利用和抗干扰两项引人注目的特性。介绍了国内外研究现状,对涡旋电磁波的产生与接收、OAM复用对通信容量的影响、OAM模式的复用和解复用、大气的非均匀性和电离层对涡旋电磁波的影响、涡旋电磁波抗干扰能力等研究热点进行了概括。指出了研究、分析OAM复用和抗干扰性能以及探索有效的OAM通信方法的重要意义。     

面向无线通信的轨道角动量关键技术研究进展

电磁涡旋因携带轨道角动量而具有高维可调制自由度,被引入无线通信中以提升频谱效率和抗干扰能力。该文首先介绍了轨道角动量和电磁涡旋的基本原理与特性;然后比较了电磁涡旋的产生方法,给出了超表面产生轨道角动量的工作原理,综述了基于超表面的轨道角动量产生方法和研究现状;总结了轨道角动量的传输性能、接收与检测方法、复用与解复用性能;最后讨论了未来在应用无线通信轨道角动量时需要解决的关键问题。     

涡旋电磁波天线技术研究进展

涡旋电磁波,因携带有轨道角动量(OAM),从而体现出除了传统的强度、相位、频率、极化等自由度之外的一种新型自由度,理论上在任意频率下都具有无穷多种互不干扰的正交模态,并且近年来其在雷达成像、无线通信等研究领域展现出重要的应用潜力,所以引起国内外学者的广泛关注,具有很高的研究价值和应用前景。在这里,该文主要介绍近年来涡旋电磁波天线技术的研究进展,包括单一微带贴片天线、阵列天线、行波天线、以及超表面天线结构等。单一微带贴片天线由于其结构简单、制作成本低而被广泛运用;行波天线可以在宽带范围内产生多OAM模式的涡旋电磁波;阵列天线的设计原理简单,可以灵活地控制产生不同模态的高增益OAM电磁波;而超表面天线不需要复杂的馈电网络,从而具有天线整体剖面较低的优势。该文对这4种常见的涡旋电磁波天线进行了总结,并展望了未来的发展趋势。      

涡旋电磁波无线通信技术的研究进展

由电磁动力学可知,电磁波可携带与极化方式相关的自旋角动量(Spin Angular Momentum,SAM)和与坡印廷矢量运动方式相关的轨道角动量(Orbital Angular Momentum,OAM).当OAM不为零时,电磁波的波前电场分布呈漩涡状且具有沿轴向传播的特性,人们形象地将这类电磁波称为涡旋电磁波.学界在平面电磁波场强数学模型的基础上引入了一个以OAM的拓扑荷l(又称模态)为参数的傅里叶旋转因子描述涡旋电磁波的波前场,因此,涡旋电磁波波前具有与拓扑荷l相关联的"极化"图案,利用不同模态的涡旋电磁波的极化图案可进一步提升无线通信系统信道容量.研究表明,在开放环境下由均匀圆阵列(Uniform Circular Array,UCA)阵列产生"平面"涡旋电磁波波束尽管可行,但要获得模态复用增益,需要探索基于复平面内单位圆周上分布的正交相位序列的涡旋电磁波波束产生与信息传输方法.文中也调研了无线射频领域OAM与MIMO体制相兼容的研究现状.     

基于多极矩展开的双模涡旋波束综合北大核心CSCD

为了增加通信系统传输容量,提高频谱效率,本文提出了一种利用多极矩展开（MME）产生携带两种不同模态轨道角动量（OAM）的涡旋电磁波的方向图综合方法。以同轴馈电的贴片天线为阵元,通过构建一个两环的同心圆环天线阵列,在保持内外环半径与激励幅值比不变的条件下来产生所需的涡旋波束。仿真结果表明,利用多极矩展开方法产生的OAM模态分别为1和2的涡旋波束的主瓣范围符合预期,同时旁瓣电平最高仅为-13.8dB。该研究为雷达成像、无线通信等领域的进一步发展提供了参考依据。     

基于多模态OAM涡旋电磁波的L波段宽频阵列天线设计

频谱资源紧缺已成为无线通信技术发展的瓶颈．本文通过控制阵元间馈电相位差将轨道角动量（orbit-al angular momentum）技术应用于阵列天线中,利用L型探针馈电微带贴片天线沿圆周等距排列设计出一种工作频段在1．35GHz～1．86GHz,相对带宽达到31．8％的8阵元涡旋电磁波宽频微带天线．仿真实验表明,该天线可以产生具有多模态轨道角动量的涡旋电磁波,当用于移动通信系统的发射端,它能够实现在同一时间、同一频率下的多路信号传输,提高了系统的容量和传输速率．     

涡旋电磁波的理论与应用研究进展

无线电技术因实现对信息的快捷传输而蓬勃发展,时至今日,不断增多的通信业务使得不可再生的频谱资源日益紧缺,通信速率也已趋于香农定理的极限。 涡旋电磁波(简称涡旋波)因携带有轨道角动量(Orbital Angular Momentum, OAM)而体现出新的自由度,理论上在任意频率下都具有无穷多种互不干扰的正交模态,在通信领域有望提升频谱效率与通信容量,在雷达成像领域也体现出提高分辨率的潜力,逐渐成为研究热点。 基于此,本文通过调研,概述了涡旋波的理论研究进展;阐述了涡旋波产生、传输、接收等传播链路的研究方法;介绍了涡旋波在无线通信领域与雷达成像领域的应用现状;总结了涡旋波在目前发展中面临的关键问题,并指出其未来研究与发展的方向。     

轨道角动量技术在无线通信中的应用

智能终端的普及以及移动互联网应用的蓬勃发展,使容量需求与频谱资源短缺的矛盾日益突出。轨道角动量可以在不增加系统带宽的情况下,极大地提高系统容量,引起业内广泛关注。本文分析了轨道角动量的工作原理,介绍了轨道角动量技术在无线通信中的研究进展,探讨了轨道角动量在无线通信中应用所面临的问题及挑战。     

涡旋电磁波轨道角动量模态抗干扰性能分析

The electromagnetic vortex wave has demonstrated excellent research value with potential applications in the fields of wireless communication and radar detection and imaging due to its unusual electromagnetic field distribution and theoretically infinite orthogonal Orbital Angular Momentum (OAM) modes. This study analyzes the anti-interference performance of OAM modes in the electromagnetic vortex Radio Frequency (RF) transceiver link primarily from the perspective of the electromagnetic vortex field distributions in space and the OAM modes orthogonality. Planar antenna arrays are designed to generate the electromagnetic vortex beams with respective OAM modes of and in the C band, and the corresponding RF transceiver links are established. The OAM modes’ anti-interference properties under different interference situations are analyzed in the electromagnetic vortex RF transceiver link by using a horn antenna as the interference source. Meanwhile, the corresponding OAM mode spectrum and the OAM modes’ orthogonality are employed as the primary methods in our analysis. Finally, the designed antenna models are fabricated, and the electromagnetic vortex RF transceiver links are measured. The corresponding analyses and conclusions are presented in this study. The OAM modes’ anti-interference performance analysis in the vortex electromagnetic wave’s RF transceiver link can provide a reference for exploring and designing a vortex electromagnetic wave in wireless communication and radar detection and imaging research.      

涡旋电磁波无线通信技术的研究进展

It is known from electromagnetic momentum that electromagnetic waves can carry Spin Angular Momentum (SAM) related to polarization and Orbital Angular Momentum (OAM) related to the trajectory of the Poynting vector. When OAM is not zero, the wave-front electric field distribution of the electromagnetic wave is vortex-like and has the characteristic of propagating along the axial direction. Therefore, this electromagnetic wave is aptly named vortex electromagnetic wave. Based on the mathematical model of the plane electromagnetic wave field, the researchers introduce a Fourier factor that uses the topological charge (also called mode) of the OAM as a parameter to describe the field of the vortex electromagnetic wave. Therefore, the wave-front of the vortex electromagnetic wave with a “polarization” pattern associated with topological charge, the use of polarization patterns of vortex electromagnetic waves in different modes can further increase the spectrum effect of the wireless communication system. Studies show that although it is feasible to generate "planar" vortex electromagnetic wave beams from Uniform Circular Array (UCA) arrays in an open environment, to obtain modal multiplexing gain, and it is necessary to explore vortex electromagnetic wave beams based on orthogonal phase sequences distributed on a unit circle in the complex plane. At the same time, the paper also investigates the current research status of compatibility between OAM and Multiple Input Multiple Output (MIMO) systems in the field of radio frequency.     

电磁涡旋及其在无线通信中的应用

随着移动数据需求的飞速增长,频谱资源紧缺的问题已成为限制无线通信产业发展的瓶颈。电磁涡旋作为一项新的传输技术,引入轨道角动量这一新的复用维度,可以实现在同一频带同时传输多路信息,有望极大地提高通信系统的容量,有效解决频率资源短缺的问题。详细分析了电磁涡旋的结构和性质,概述了电磁涡旋的国内外研究进展,阐述了电磁涡旋的产生与接收方法及复用技术原理,指出了电磁涡旋面临的挑战与后续研究建议。     

Research on orbital angular momentum communication technology

As the good orthogonality between the different modes of orbital angular momentum (OAM),the application of OAM technology in wireless communication has gained increasing popularity in recent years with great potential for capacity improvement.OAM-based wireless communication technology can effectively improve spectrum utilization,but also brings some challenges.Firstly,the research status and progress of OAM technology in the field of wireless communication were introduced and the relationship between OAM and MIMO technology was compared and analyzed combined with the basic principle of OAM.Moreover,the dispute “Does OAM provides a new dimension?” was concluded.Then,the generation and reception methods of OAM were summarized.The key techniques and application fields were overviewed.Finally,the challenges of the technology in practical application were analyzed and the future development trends and follow-up research directions were point out,which would provide a reference and help for the research in this field.     

Optimized planar printed UCA configurations for OAM waves and the associated OAM mode content at the receiver

Utilization of planar printed uniform circular antenna arrays (UCA) to generate the orbital angular momentum (OAM) carrying waves in the millimeter-wave (mmWave) frequency band is advantageous from the viewpoints of easy signal modulation and mode reconfiguration, low cost, low profile, and straightforward integration with the existing broadband wireless infrastructure. The OAM mmWave UCA are highly promising as the enablers of very high transmission data rates required by hybrid 5G/6G optical and wireless communication systems by complementing and enhancing other technologies currently in use. Therefore, we here contribute a detailed electromagnetic analysis of important constraints of such antenna arrangements aimed at short-range multimode OAM wave transmission. We investigate (i) the required antenna array dimensions and optimized UCA arrangements for a particular link range and (ii) the corresponding mode structure of OAM waves in the plane of receiving arrays. Four relatively simple antenna configurations operating in the 60-GHz band are compared. Theoretical assumptions based on ideal OAM modes are critically assessed and, using state-of-the-art numerical electromagnetic analysis, compared to realistically generated OAM waves. The proposed “cyclic transmission setup” resulted in much lower unwanted field components in the region of receiving arrays. RMS magnitudes of unwanted modes are on average about 64% of the received mode, in comparison with 80% (up to 94%) for sequential transmission. The observed mode impurities and mode mixing effects at the receiver indicate the need to dedicate more attention to the system-level design, the development of efficient receiving arrays, the MIMO processing, and the stream separation.     

无线通信应用太赫兹技术研究进展

在过去的几年里,由于不同频段电磁频谱的传播特性差异、对带宽需求以及技术利用能力提升,无线通信应用的电磁频谱不断提高。在通信领域,为满足无线数据传输需求的爆炸性增长,特别是5G通信的发展,毫米波中低频段应用已经成功实现工程化并开始商业化。而对于以光波为载体的更高频率电磁波的光通信,也已经发展了几十年。在常规无线电波(毫米波)与常规光学(远红外)之间,存在着一段长期未能有效利用的空闲频谱资源,目前被统称为太赫兹频段(0.1~10 THz)。太赫兹频段在高速无线通信领域具备明显优势,成为有潜力的6G通信核心技术。可以预见,对这项技术的使用将助力6G通信实现网络全覆盖、高度智能化及网络安全性全面提升的愿景。文章主要关注通信领域,重点介绍了太赫兹频段的特点、构建太赫兹系统功能的器件类型与工艺集成实现技术。最后,预测了太赫兹通信技术的一些应用场景,进而显示出该技术对通信领域和人们日常生活的促进作用。