Dual-Channel Communication of Column Plasma Antenna Excited by a Surface Wave——Actualization and Simulation of Radiation Pattern

Along with the introduction of the concept of dual-channel communication,we utilized the finite-difference time-domain（FDTD） method to simulate and measure the radiation pattern under certain plasma densities and plasma collision frequencies.Results show that under certain settings,the radiation pattern of a plasma antenna resembles that of a metallic antenna.In contrast to a metallic antenna,a plasma antenna possesses other functionalities,such as dynamic reconfiguration and digital controllability.The data from simulation are similar to the measurement results,indicating that column plasma antenna can realize dual-channel communication.This work confirms the viability of realizing dual-channel communication by column plasma antenna,which adds a new but promising method for modern intelligent communication.

Reconfigurable Pattern Patch Antenna for Mid-Band 5G:A Review

New requirements in communication technologies make it imperative to rehash conventional features such as reconfigurable antennas to adapt with the future adaptability advancements.This paper presents a comprehensive review of reconfigurable antennas,specifically in terms of radiation patterns for adaptation in the upcoming Fifth Generation(5G)New Radio frequency bands.They represent the key of antenna technology for materializing a high rate transmission,increased spectral and energy efficiency,reduced interference,and improved the beam steering and beam shaping,thereby land a great promise for planar antennas to boost the mid-band 5G.This review begins with an overview of the underlying principals in reconfiguring radiation patterns,followed by the presentations of the implemented innovative antenna topologies to suit particular advanced features.The various adaptation techniques of radiation pattern reconfigurable planar antennas and the understanding of its antenna design approaches has been investigated for its radiation pattern enhancement.A variety of design configurations have also been critically studied for their compatibilities to be operated in the midband communication systems.The review provides new insights on pattern reconfigurable antenna where such antennas are categorized as beam steering antenna and beamshaping antennas where the operation modes and purposes are clearly investigated.The review also revealed that for mid-band 5G communication,the commonly used electronic switching such as PIN diodes have sufficient isolation loss to provide the required beam performance.

Antenna Array Pattern Synthesis via Coordinate Descent Method

This paper presents an array pattern synthesis algorithm for arbitrary arrays based on coordinate descent method (CDM). With this algorithm, the complex element weights are found to minimize a weighted L2 norm of the difference between desired and achieved pattern. Compared with traditional optimization techniques, CDM is easy to implement and efficient to reach the optimum solutions. Main advantage is the flexibility. CDM is suitable for linear and planar array with arbitrary array elements on arbitrary positions. With this method, we can configure arbitrary beam pattern, which gives it the ability to solve variety of beam forming problem, e.g. focused beam, shaped beam, nulls at arbitrary direction and with arbitrary beam width. CDM is applicable for phase-only and amplitude-only arrays as well, and furthermore, it is a suitable method to treat the problem of array with element failures.

Achieving Directionality and Transmit Diversity via Integrating Beam Pattern Scanning (BPS) Antenna Arrays and OFDM

In this paper, we introduce a novel merger of antenna arrays with scanning beam patterns, and Orthogonal Frequency Division Multiplexing (OFDM) systems. Controlled time varying phase shifts are applied to the antenna array elements mounted at the base station with beam patterns directed toward the desired user. This creates a small beam pattern movement called Beam Pattern Scanning (BPS). In rich scattering environments BPS creates a time varying environment leading to time diversity exploitable at the receiver enhances its probability-of-error performance. Here, we apply OFDM signals to BPS antenna arrays, and we achieve: (1) directionality, which supports Space Division Multiple Access (SDMA);and (2) a time diversity gain, which leads to high performance. We discuss the structure of the base station antenna array and the OFDM receiver that exploits time diversity. We also introduce the merger of BPS and multi-carrier OFDM (MC-OFDM) systems. In MC-OFDM each bit is transmitted over all sub-carriers after serial to parallel conversion. BPS/ MC-OFDM receiver exploits both time diversity inherent in BPS, and frequency diversity inherent in MC-OFDM transmission technique. Simulation results show high Probability-of-error performance is achie- vable via BPS/OFDM and BPS/MC-OFDM schemes comparing to the traditional OFDM and MC-OFDM, respectively. Simulations also reveal that MC-OFDM system as well as its merger with BPS is capable of mitigating large Peak-to-Average Ratio (PAPR) problem in traditional OFDM system. In addition, performance simulations with coded OFDM (COFDM) and coded MC-OFDM (MC-COFDM) and their merger with BPS are studied.

一种等通量波束的多极化可重构天线

随着航天技术的革新,对近地轨道的通信需求逐年增高。近地轨道卫星就在此背景下产生,主要应用于遥感探测天气预报和数据通信领域。由于近地轨道卫星天线辐射波束所覆盖的地球表面是球面,因此波束通常设计为等通量形式。由于卫星通信通常存在极化失配、多径效应等问题,选择多极化而不是圆极化作为近地卫星天线的工作状态能更好地适应复杂的工作环境,保证通信质量,将等通量波束天线和多极化可重构技术结合起来有很大的应用前景。基于一对正交圆极化波能合成线极化波的设计原理,文中提出了一种具有等通量波束的多极化可重构天线,该天线由可重构馈电网络和带扼流环的隔片极化器圆波导组成。馈电网络中嵌入单刀四掷开关(SP4T)与单刀双掷开关(SP2T),通过改变开关的工作状态,馈电网络将给圆波导提供不同的馈电条件,在圆波导内隔片的作用下天线实现两种圆极化与两种线极化的可重构。通过在圆波导口引入扼流环以及波导口作“T”型开槽处理,实现波束赋形,并且保证天线在不同极化状态下辐射等通量波束。实测结果显示,天线在不同的极化状态下-15 dB重叠阻抗带宽14.7%,覆盖4.80~5.56 GHz,方向图顶部在θ为-24°~+24°范围内具有平坦效果,圆极化状态下空间轴比覆盖-51°~+50°,覆盖范围大于方向图顶部平坦范围。天线实测结果与仿真结果有较好的一致性,具有多极化和方向图顶部平坦的优势,可满足移动通信和卫星通信中多极化应用场景的需要。

数模混合二维相控阵雷达远场收发校准方法研究

本文提出了一种基于最小系统设计准则的数模混合二维相控阵雷达远场收发校准方法,给出了实现流程、数据分析过程和实测结果。方向图的实测结果显示本文提出的校准方法得到的收发方向图主要技术指标良好且均满足使用要求,在实际工程中具有较好的操作性和推广性。

基于5G新空口的感知通信一体化多波束系统

由于多波束通信信道中的重要信号会受到传播距离的影响,存在串行干扰和噪声,致使天线方向图与实际数值不一致。针对该问题,设计一种基于5G新空口的感知通信一体化多波束系统。通过5G新空口多波束基站、多波束基站天线自动对准平台以及多波束采集控制平台三部分,设计感知通信一体化多波束系统硬件结构;并在系统硬件结构基础上设计系统软件部分,采用多波束形成方法设计5G新空口多波束赋形接收和发射子系统,获取天线方向图。在子系统内,通过5G新空口混合时空编码,采用QR分解构建多波束分解信道矩阵,消除编码过程中存在的串行干扰;根据信道分解结果,采用基于通道映射的方法提取多波束通信信道中的重要信号。通过系统硬件和软件设计构建基于5G新空口的感知通信一体化多波束系统。系统测试结果表明,所设计系统多波束成形是向中心点聚拢的,天线方向最大值为0,与理想图完全重合,能够实现多波束稳定传输。

基于生成对抗网络的天线三维方向图室外测量方法

天线方向图测量是天线测量的重要内容。针对天线方向图室外测量困难的问题,提出了一种基于生成对抗网络的天线三维方向图室外测量方案。该方案利用无人机对天线方向图数据进行采集,对采集的数据进行修正,获得待测天线和接收天线极化匹配时的直射径数据,最后利用训练好的生成对抗网络重构出天线的三维方向图。仿真结果表明,本方案可以高效、高精度地完成天线三维方向图的测量,具有一定的实用价值。

DSRT三轴低频天线指向误差批量测量和校正方法

稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope, DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分,工作在150–450 MHz频段,可提供高空间、高时间分辨率的太阳爆发亮温图像.针对DSRT天线的高精度指向测量以及对指向误差批量标定和校正的需求,首先根据DSRT独有的三轴座架系统,通过四元数旋转变换法建立了天线3参数编码器零点误差模型;然后提出了基于射电源的漂移扫描法获得16个单元天线功率方向图,并根据2维方向图确定波束中心的方法精确测量了DSRT天线指向误差;最后用最小二乘法拟合得到模型参数,并通过天线控制软件重新调整各个轴的零点,后对调整结果进行验证.结果表明指向校正方法可靠有效,校正后16个天线的指向精度为0.5°之内,明显优于校正前3.5°的指向误差,满足误差小于DSRT天线最高工作频率下的1/10波束范围内的要求.

基于波束优化赋形方法的斜视星载SAR模糊抑制研究

距离模糊和方位模糊会严重影响星载合成孔径雷达(Synthetic Aperture Radar,SAR)的成像质量。现有的利用天线波束赋形来抑制模糊的方法在雷达正侧视成像时取得了优异的效果,但并不适用于雷达斜视的情况。针对这一问题,提出了一种基于平面阵列天线波束赋形的星载SAR二维模糊(距离和方位模糊)抑制方法。使用距离-方位模糊综合的模糊比(Ambiguity to Signal Ratio,ASR)指标来替代距离模糊比及方位模糊比,结合对不同斜视情形下天线波束变化的分析,充分考虑包含镜像模糊区在内的所有模糊区,建立了模糊比-天线权重优化模型。以模糊能量为目标函数、天线方向图掩模作为约束确立二次锥(Quadratic Cone Programming,QCP)优化问题,求解得到阵元幅度相位分布。仿真结果表明,所提方法可以通过调节模糊区对应的旁瓣幅值,灵活地抑制SAR斜视成像的距离和方位模糊,进而提高星载SAR的成像质量。

边射波束和锥状波束可重构的微带贴片天线

本文提出了一种边射波束和锥状波束可重构的新型微带贴片天线,该天线在锥状波束模式下具有圆度较好、锥角可设计的优点。首先,在贴片的中间引入一排短路孔,当短路孔两侧的探针反相馈电时,贴片上两侧电流同向,辐射边射波束;而当两个探针同相馈电时,贴片上两侧电流反向,辐射锥状波束。接着,对短路排孔与贴片边缘之间的间距进行了优化设计,调整电流分布,从而改善锥状波束在方位面上的圆度。最后,在贴片的对角线上额外引入了四个短路孔,通过控制其位置和大小来调节固定频率下贴片的尺寸,从而设计出不同锥角的锥状波束。通过全波仿真,设计了三个边射波束和锥状波束可切换的贴片,锥状波束的锥角分别为55°、50°和45°,均具有较好的圆度。

基于机械臂毫米波天线测试系统设计与实现

测试天线波瓣图是分析天线性能的重要方法,随着毫米波天线的大量应用,如何开发出部署灵活,成本较低的毫米波天线测试系统,成为毫米波天线大批量生产的关键,针对此问题,开发出了基于机械臂的毫米波天线测试系统;同时,针对目前平面天线测试系统测试功能单一的问题,基于机械臂的毫米波天线测试系统,不仅能够执行平面近场测试,还能够进行柱面近场、球面近场以及远场测试任务;通过对机械臂实际的精度测量实验和机械臂关键运动参数的计算,验证了基于机械臂测量毫米波天线的可行性并为系统软件设计提供了理论基础;通过与传统平面天线测试系统测试数据比较,增益偏差0.73%,波束宽度偏差1.4%,副瓣偏差1.37%,测试结果一致性较好;实际应用表明该系统能够满足毫米波天线的测试需求,为毫米波天线测试提供了重要手段。

基于粒子群算法的相控阵海浪波谱仪天线增益校正方法

相控阵海浪波谱仪是一个Ku波段真实孔径雷达,通过在小入射角下照射海面,接收海面回波功率,并去除雷达EIRP(Effective Isotropically Radiated Power,等效全向辐射功率)、天线方向图、系统损耗等雷达自身的影响因子,获取海面三维信息。这些影响因子可以在微波暗室中测量,其中EIRP、系统损耗可认为是常数量,但是,天线方向图是与入射角、方位角相关的三维变量,测量受到暗室系统精度的限制,并且,相控阵海浪波谱仪最小处理单元是雷达照亮的圆环形条带,照射的过程即是对该环形条带中的变量进行二维积分,成为一个随入射角变化的后向散射系数剖线,因此,天线方向图的微小误差,都会对海面后向散射系数剖线形状产生显著影响,出现“凹现象”问题。针对该问题,本文基于粒子群算法进行了积分天线增益的校正工作,利用机载飞行试验数据进行了算法验证,通过与同步观测浮标海浪测量结果比对,表明本算法可有效改善“凹现象”,使回波数据有效率提升了12%,为业务化的波浪谱生产提供了技术支撑。

机载天线方向图测试的试飞方法分析

鉴于通过天线方向图能够直观清晰地衡量机载天线的辐射特性,且基于试飞的测试方法所得方向图更能反映天线在实装环境下的性能,提出了一种基于圆航线试飞的天线方向图测试方法。对圆航线和“梅花瓣”航线下机载天线方向图的测试情况进行了对比分析;介绍了圆航线下天线方向图测试数据的预处理方法,即场强折算和方向角折算方法。测试结果表明:基于圆航线试飞的天线方向图测试方法效率较高,所得方向图的方向性能优良,在作战运用中具有较强的指导作用。

扫描雷达未知天线方向图误差下的稀疏目标角超分辨重建方法

扫描雷达角超分辨技术是基于目标与天线方向图的关系,采用解卷积方法获取超越实波束的角分辨能力。目前的角超分辨方法大都是基于理想的无畸变天线方向图,未考虑实际过程中方向图的变化。然而,由于雷达天线罩、天线测量误差与平台非理想运动等因素的影响,天线方向图在实际中往往存在未知的误差,会导致目标分辨能力下降,甚至产生虚假目标。针对此问题,该文提出一种机载扫描雷达未知天线方向图误差下的角超分辨成像方法。首先,基于总体最小二乘(TLS)准则,该文考虑了方向图误差矩阵的影响,导出了相应的目标函数;其次,基于交替迭代的求解思路,利用迭代重加权优化方法实现了目标函数求解;最后,针对算法超参数选取,引入了一种自适应参数选取方法。仿真与实测结果表明,该文方法能实现未知天线误差条件下的超分辨重建,进一步提升了超分辨算法的稳健性。

改进哈里斯鹰算法用于阵列天线方向图赋形

由于目前群智能优化算法在解决直线阵列天线方向图的旁瓣电平抑制和零陷控制问题时容易陷入局部最优以及收敛速度较慢的问题,提出了一种改进哈里斯鹰优化算法。该算法首先引入单鹰探索策略来扩大算法的全局搜索范围,然后引入自适应控制理论,用以提高算法的搜索精度并加快算法的收敛。仿真结果表明,与粒子群算法、布谷鸟搜索算法、蚁群优化算法以及标准哈里斯鹰优化算法相比,所提算法在压低直线形阵列天线方向图的旁瓣电平和控制零陷方面更具优越性。

短波天线性能无人机测试系统研制与应用

短波天线的尺寸大,天线方向图和增益测量困难。研制的短波天线性能无人机测试系统,利用无人机搭载三轴全向选频式场强仪,在天线远场区,无人机按照规划航线水平或垂直环绕被测天线飞行,自动采集频率、场强,并与经纬度、高程聚合为数据记录,经计算和校准修正后得到天线的方向图和增益等关键性能。系统测量频率范围2~30 MHz,测量灵敏度1 mV/m,各向同性≤1 dB,频率响应≤1 dB;测量比对表明:系统测量电场精度达到±1.5 dB。实测了偶极子天线、单极天线的方向图和增益,经对比,实测与仿真的结果一致性很好,无人机测试系统具有较高的测试精度。

Optimal Design of Wireless Power Transmission Systems Using Antenna Arrays

Three design methods for wireless power transmission(WPT)systems using antenna arrays have been investigated.The three methods,corresponding to three common application scenarios of WPT systems,are based on the method of maximum power transmission efficiency(MMPTE)between two antenna arrays.They are unconstrained MMPTE,weighted MMPTE,and constrained MMPTE.To demonstrate the optimal design process with the three methods,a WPT system operating at 2.45 GHz is designed,simulated,and fabricated,in which the transmitting(Tx)array,consisting of 36 microstrip patch elements,is configured as a square and the receiving(Rx)array,consisting of 5 patch elements,is configured as an L shape.The power transmission efficiency(PTE)is then maximized for the three application scenarios,which yields the maximum possible PTEs and the optimized distributions of excitations for both Tx and Rx arrays.The feeding networks are then built based on the optimized distributions of excitations.Simulations and experiments reveal that the unconstrained MMPTE,which corresponds to the application scenario where no radiation pattern shaping is involved,yields the highest PTE.The next highest PTE belongs to the weighted MMPTE,where the power levels at all the receiving elements are imposed to be equal.The constrained MMPTE has the lowest PTE,corresponding to the scenario in which the radiated power pattern is assumed to be flat along with the Rx array.

基于稀疏空间采样的雷达阵列天线主波束指向估计

天线主波束指向代表了雷达的能量集中方向,其在电子对抗领域是一个十分重要的信息。当已知雷达天线的主波束指向时,可以避开目标雷达的探测或对其实施精准的电子干扰。基于雷达周围部署的少量观测点,构建噪声环境下的稀疏空间采样数学模型,并提出四种雷达阵列天线主波束指向的估计算法。蒙特卡洛仿真测试结果展示了所提算法在不同条件下的估计准确性。

基于有源超表面天线罩的窄截面方向图可重构天线

针对无人机数据链通信存在抗干扰性能差、防捕获能力弱等问题,提出了一种具有良好气动性能的基于有源超表面天线罩的窄截面方向图可重构天线。该天线由宽带平面印刷全向天线、窄截面有源超表面天线罩以及双频阻抗匹配网络组成。当超表面天线罩上二极管均截止(未加偏置电压)时,天线罩处于全透波状态,天线工作于宽带全向通信模式。当超表面天线罩特定区域二极管导通时,该区域天线罩处于全屏蔽状态,天线工作于双频定向通信模式,此时通过引入双频阻抗匹配网络显著改善天线的阻抗匹配。全向通信模式下,天线相对带宽达到44.6%,全向增益可达1.37 dBi,不圆度小于2.5 dBi;定向模式下,双频天线上下频带分别为1.4 GHz和1.8 GHz,相对带宽分别为9.1%和15.3%,最大定向增益达5.2 dBi。该天线具有窄截面、低成本等优点,能够在宽带全向通信和双频定向通信工作模式之间灵活切换,有望提高无人机抗干扰、防捕获的性能。