A 1-bit electronically reconfigurable beam steerable metasurface reflectarray with multiple polarization manipulations

A 1-bit electronically controlled metasurface reflectarray is presented to achieve beam steering with multiple polarization manipulations. A metsurface unit cell loaded by two PIN diodes is designed. By switching the two PIN diodes between ON and OFF states, the isotropic and anisotropic reflections can be flexibly achieved. For either the isotropic reflection or the anisotropic reflection, the two operation states achieve the reflection coefficients with approximately equal magnitude and 180°out of phase, thus giving rise to the isotropic/anisotropic 1-bit metasurface unit cells. With the 1-bit unit cells, a 12-by-12 metasurface reflectarray is optimally designed and fabricated. Under either y-or x-polarized incident wave illumination, the reflectarray can achieve the co-polarized and cross-polarized beam scanning, respectively, with the peak gains of 20.08 d Bi and 17.26 d Bi within the scan range of about ±50°. With the right-handed circular polarization(RHCP) excitation, the left-handed circular polarization(LHCP) radiation with the peak gain of 16.98 d Bic can be achieved within the scan range of ±50°. Good agreement between the experimental results and the simulation results are observed for 2D beam steering and polarization manipulation capabilities.

Improved Beam Steering Method Using OAM Waves

Orbital Angular Momentum(OAM)is an intrinsic feature of electromagnetic waves which has recently found many applications in several areas in radio and optics.In this paper,we use OAM wave characteristics to present a simple method for beam steering over both elevation and azimuth planes.The design overcomes some limitations of traditional steering methods,such as limited dynamic range of steering,the design complexity,bulky size of the steering structure,the limited bandwidth of operation,and low gain.Based on OAM wave characteristics,the proposed steering method avoids design complexities by adopting a simple method for generating the OAM-carrying waves.The waves are generated by an array of Planar Circular Dipole(PCD)elements.These elements are designed to cover a wide bandwidth range between 3 and 30 GHz.The transmitting array shows an enhanced gain value from 8.5 dBi to almost 11.5 dBi at the broadside angle.Besides the enhanced PCD-based OAM generation,the novelty of the design lies in a new method of beam steering.Beam steering is then performed by controlling the electrical feeding of the PCD elements;the beam azimuthal location is managed by turning off some of the PCD elements,while the elevation is determined by changing the gradient phase of excitation for the turned-on PCD elements.Detailed analysis of the steering method is carried out by finding the mathematical model of the system and the generated waves.The performance has been verified through numerical simulators.

PERFORMANCE ANALYSIS OF AZIMUTH ELECTRONIC BEAM STEERING MODE SPACEBORNE SAR

Pointing angle and pattern of the antenna can be changed swiftly to actualize the azimuth beam scanning by using electronic beam steering, which makes the Synthetic Aperture Radar (SAR) system more flexible and achieve a high resolution or cover a long strip within short time span. When the pointing angle is steered away from boresight, some aberrations may appear on the antenna pattern, e.g., the grating lobe appears, the main lobe gain decrease, and antenna pattern broadens, e.g., the aberrations result in the worsening of system performance, and complicate the corresponding performance analysis method. Conventional computation methods of performance parameters do not account for the rapid change of the antenna pattern. It introduces remarkable errors when the scanning angle is large. In this paper, a method of calculating performance parameters is proposed for the beam steering mode, which achieves the parameters by the energy accumulation in time domain. Actually, the proposed method simulates the working process of SAR and obtains accurate performance parameters. Furthermore, we analyze the effects of the grating lobe on the Azimuth Ambiguity to Signal Ratio (AASR), and present the generic Pulse Repetition Frequency (PRF) choosing principle which can also prevent the ambiguous area from weighting by the grating lobe. Finally, the effect of the antenna configuration on the performance parameters is analyzed by a system example.

Ultrasonic beam steering using Neumann boundary condition in multiplysics

The traditional one-dimensional ultrasonic beam steering has time delay and is thus a complicated problem. A numerical model of ultrasonic beam steering using Neumann boundary condition in multiplysics is presented in the present paper. This model is based on the discrete wave number method that has been proved theoretically to satisfy the continuous conditions. The propagating angle of novel model is a function of the distance instead of the time domain. The propagating wave fronts at desired angles are simulated with the single line sources for plane wave. The result indicates that any beam angle can be steered by discrete line elements resources without any time delay.

Programmable agile beam steering based on a liquid crystal prism

To meet the application need for agile precision beam steering, a novel liquid crystal prism device with a simple structure, convenient control, low cost and applicable performance is presented, and analysed theoretically and experimentally. The relationships between the optical path and the thickness of the liquid crystal cell under different voltages are investigated quantitatively by using a theoretical model. Analysis results show that the optical path profile of the liquid crystal prism has a quasi-linear slope and the standard deviation of the linear slope is less than 16 nm. The slope ratio can be changed by a voltage, which achieves the programmable beam steering and control. Practical liquid crystal prism devices are fabricated. Their deflection angles and wavefront profiles with different voltages are experimentally tested. The results are in good agreement with the simulated results. The results imply that the agile beam steering in a scope of 100μrad with a micro-rad resolution is substantiated in the device. The two-dimensional beam steering is also achieved by cascading two liquid crystal prism devices.

Beam steering characteristics in high-power quantum-cascade lasers emitting at∼4.6µm

A beam steering effect of high-power quantum cascade(QC) lasers emitting at 4.6 μm was investigated. The continuous wave(CW) output power of an uncoated, 6-mm-long, 7.5-μm-wide buried-heterostructure QC laser at 25℃ was as high as 854.2 m W. The maximum beam steering angle was offset by ±14.2° from the facet normal(0°) in pulsed mode. The phenomenon was judged explicitly by combining the diffraction limit theory and Fourier transform of the spectra. It was also verified by finite element method software simulation and the calculation of two-dimensional(2 D)effective-index model. The observed steering is consistent with a theory for coherence between the two lowest order lateral modes. Therefore, we have established an intrinsic linkage between the spectral instabilities and the beam steering by using the Fourier transform of the spectra, and further presented an extremely valid method to judge the beam steering. The content of this method includes both three equidistant peak positions in the Fourier transform of the spectra and the beam quality located between once the diffraction limit(DL) and twice the DL.

Broadband beam steering for misaligned multi-mode OAM communication systems

Orbital angular momentum(OAM)at radio frequency(RF)has attracted more and more attention as a novel approach of multiplexing a set of orthogonal OAM modes on the same frequency channel to achieve high spectral efficiency(SE).However,the precondition for maintaining the orthogonality among different OAM modes is perfect alignment of the transmit and receive uniform circular arrays(UCAs),which is difficult to be satisfied in practical wireless communication scenarios.Therefore,to achieve available multi-mode OAM broadband wireless communication,we first investigate the effect of oblique angles on the transmission performance of the multi-mode OAM broadband system in the non-parallel misalignment case.Then,we compare the UCA-based RF analog and baseband digital transceiver structures and corresponding beam steering schemes.Mathematical analysis and numerical simulations validate that the SE of the misaligned multi-mode OAM broadband system is quite low,while analog and digital beam steering(DBS)both can significantly improve the SE of the system.However,DBS can obtain higher SE than analog beam steering especially when the bandwidth and the number of array elements are large,which validates that the baseband digital transceiver with DBS is more suitable for multi-mode OAM broadband wireless communication systems in practice.

Ultra-thin two-dimensional transmissive anisotropic metasurfaces for polarization filter and beam steering application

We propose an anisotropic planar transmitting metasurface, which has the ability to manipulate orthogonally-polarized electromagnetic waves in the reflection and refraction modes respectively. The metasurface is composed of four layered rectangular patches spaced by three layered dielectric isolators each with a thickness of 0.15λ0 at 15 GHz. By tailoring the sizes of the patches, the metasurface functions as a band-stop filter for the y-polarzied wave and a band-pass filter for the x-polarized wave operating from 14 GHz to 16 GHz. Moreover the phases of the transmitting x-polarized wave can be modulated at about 15 GHz, which contributes to beam steering according to the general refraction law. Experimental results are in good accordance with the simulated ones, in which the reflection efficiency is almost 100% while the transmission efficiency of the x-polarized wave reaches 80% at 15 GHz. Besides, the transmitted x-polarized wave is effectively manipulated from 14 GHz to 16 GHz.

Beam Steering Analysis in Optically Phased Vertical Cavity Surface Emitting Laser Array

Beam steering in implant defined coherently coupled vertical cavity surface emitting laser （VCSEL） arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences among elements, inter-element spacing, element size and emitted wavelength is analyzed detailedly and systematically. We design and fabricate 1×2 implant defined VCSEL arrays for optimum beam steering performance. Electroni- cally controlled beam steering with a maximum deflection angle of 1.6° is successfully achieved in the 1 × 2 VCSEL arrays. The percentage of the power in the central lobe is above 39% when steering. The results show that the steering is controllable. Compared with other beam steering methods, the fabrication process is simple and of low cost.

机载一维相扫雷达空域稳定算法研究

传统上机载雷达是采用硬件稳定平台保持天线扫描空域稳定的,如今采用数据处理方法保持扫描空域电子稳定的研究正在引领发展趋势。文中针对机载平台运动引起天线波束指向角的改变以及由此带来的探测精度下降甚至目标丢失的问题,系统地探讨了一维相扫机载雷达保持扫描空域稳定的波束控制方法,建立了机载运动平台下指向角变换的数学模型,推导出由于平台运动引起的波束指向角变换公式,设计了一维相扫移相码的计算方法,通过仿真验证了计算精度、计算时间、波束指向精度和移相器位数选取等关键技术指标。结果表明空域稳定算法有效可靠,为机载相控阵雷达波束控制设计提供了通用化的设计思路,具有较大的工程意义和实用价值。

基于超材料的水声通信综述

近年来,声学超材料作为一种新型人工复合材料,凭借其强大的声学参数调控能力突破传统材料功能极限,在水下探测、目标识别、成像、导航和通信等领域展现出了广阔的应用前景。文章综述了利用超材料实现水声通信的研究进展,主要包括基于声轨道角动量的多路复用通信、基于声学超表面的波束操控实现的特定发射和接收端间的水声通信,以及水-空跨介质声通信,总结了其所涉及的关键技术,并对当前基于超材料的水声通信所面临的挑战和前景进行了展望。

基于密度锥削阵sin-FDA的波束方向图研究

频率分集阵列(Frequency Diverse Array, FDA)是作为一种全新的电扫描雷达体制,其方向图所具有的时间-距离-角度三维相关特性在电子对抗和安全通信等领域有广阔的应用前景。一维均匀线性FDA阵列(Uniform Linear Array Frequency Diverse Array, ULFDA)的发射方向图存在角度-距离耦合问题,针对这一问题,在对称子阵密度锥削阵结构的基础上,通过正弦频控函数取代原有的均匀线性函数,得到了FDA的点状波束指向控制方法。此外,针对FDA方向图的时变问题,得到了基于子阵结构的密度锥削阵sin-FDA主波束在角度维指向固定、距离维变化时的结论。

三维高增益相控阵天线阵列机相扫模式下的波束控制算法

针对在二维平面相控阵天线和椭球天线罩之间增加引向天线会使天线阵列的辐射相位中心由二维扩展到三维,经典的平面相控阵波束控制算法不再适用的问题,基于高增益引向天线阵列,提出一种三维阵列的波束控制算法,在机相扫模式下修正脉间波束指向,提高波束扫描精度,并给出了工程实现的具体流程,最后通过地面测试验证了新算法的性能优势,并通过空中配试靶机验证了新算法的探测性能。

An Evolutionary Approach to Improve the Beam Steering Performance over Conventional Approach in CHAA

In this work,evolutionary algorithms are applied for the first time to achieve better radiation characteristics over the conventional beamforming algorithm in the concentric hexagonal antenna array(CHAA),which improves the performance of wireless communication.Multiple signal classification(MUSIC)algorithm is employed for direction of arrival(DoA)estimation.The conventional adaptive beam steering algorithm,least mean-square(LMS)algorithm,is used to steer the beam.Further,the proposed approach is employed by novel particle swarm optimization(NPSO)to reduce sidelobe level(SLL)even further.A six-ring CHAA with 126 elements for DoA estimation and beam steering is simulated.The simulation results of the MUSIC,LMS,NPSO,and particle swarm optimization(PSO)algorithms are provided for various DoAs.

面向光束指向调控的双快速反射镜偏转角快速解算方法

基于双快速反射镜的光束指向调控系统可补偿光束位置偏差及角度偏差,双反射镜引入的耦合效应致使难以快速求解合适的镜面绕轴偏转角。为解决该问题,文中构建了双快速反射镜光束指向调控模型,分析了偏转角与光斑位移在小角度下的近似线性关系,提出了偏转角的快速解算方法,可在单次求解后获得适用的镜面偏转角。该方法采用迭代收敛算法解算抑制随机光束指向失调的偏转角并形成数据集,基于该数据集训练浅层神经网络,可根据当前光斑位置偏差直接解算快速反射镜偏转角。仿真实验结果表明,依据该方法解算的偏转角进行调控,相较于未调控前光束状态,在X和Z方向的位置偏差分别减小99.32%、99.46%,角度偏差分别减小99.07%、98.98%,平均综合偏差减小99.16%,极大地抑制了光束指向失调。

Low-Cost Beam Steering that Covers the Entire Azimuthal Plane Powered by Amplitude-Only Synthesis of a Quintuple-Dipole Source

A new amplitude-only synthesis approach in quintuple electric dipoles(EDs)is proposed to enable the regulation of power flow in the azimuthal plane.The regulation methodology is investigated analytically with double ED,triple ED and quintuple ED models.First,when the phase difference between the EDs switches,the double ED model,acting as a reconfigurable source,can work in two modes with different power flow directions,i.e.,unidirectional mode and bidirectional mode.Then,from the triple ED model,it is verified that the power flow in the two working modes can be regulated to the desired direction in the azimuthal plane with high precision by controlling the feeding amplitudes of the dipoles.Moreover,a quintuple ED model is developed to enhance the symmetry and consistency of the power flow regulation in the plane.Finally,a prototype of the azimuthal beam steering system,including digitally controlled radio-frequency(RF)frontend tuning circuits,optimized practical feeding elements,and an end-fire radiator,is designed,fabricated and measured.Both unidirectional and bidirectional modes are observed,and satisfactory single-beam and dual-beam steering performance in the azimuthal plane is achieved.Unlike most phased arrays that realize beam steering by configuring phases,the beam steering of the proposed reconfigurable source in each mode can be arbitrarily synthesized only by the amplitudes of the quintuple feeding elements,which provides a new route for realizing low-cost and multifunctional beam-steering systems.

智能近远光灯系统的研究

随着现代城市化进程的不断加速,人们的日常生活与消费需求的变迁,交通安全问题成为了人们关注的重要议题。以传统车灯为基础,并添加了人工智能(Artificial Intelligence,AI)技术,旨在降低因使用近远光灯不当所导致的交通事故风险,从而保障出行安全。系统采用单片机为控制核心,太阳能供电,使用光敏电阻检测光照强度,并可进行自动、手动模式转换,舵机用于控制灯光的角度。单片机可接收信息并驱动转换系统对车灯进行精细控制。研究设计的智能车灯系统能够合理地根据道路光照情况使用车灯,有效避免人为原因所导致的事故风险,并能大幅度减少能源的浪费,从而实现低碳环保的目标。

基于可重构PRS的一维电子波束转向Fabry-Perot天线设计

设计了一种具有一维电子波束转向的新型Fabry-Perot(F-P)谐振腔天线。该天线由同轴探针馈电的方形微带贴片天线作为辐射源,并采用加载PIN二极管的可重构部分反射表面(Partially Reflective Surface,PRS)实现波束转向。所设计的可重构PRS由6×6个花瓣型单元组成,并均分为相等的两部分Part 1和Part 2,分别由两个控制信号独立控制,因此可以有选择地调节每部分PIN二极管的开关状态。所设计的天线具有三种不同的辐射模式。测量结果表明,天线主波束能够在+9°、0°、-9°三种离散状态下自由切换。所有状态下重叠的阻抗带宽(|S_(11)|<-10 dB)为5.5%(5.43~5.74 GHz),最大增益达到14.2 dBi。

微带漏波天线及其波束控制方法

漏波天线是一类具有广大应用前景的导波天线,与传统天线相比具有明显的优势,可为各种无线通信和雷达应用提供波束控制功能。本文提出一种使用容性负载实现方向图动态辐射模式控制的漏波天线设计及波束控制方法。波束控制方法作为研究的主要重点,即在天线结构的特定位置引入电容元件来调制导波的有效折射率,通过改变波束的辐射角度来实现波束的控制。此外,研究还通过改变容性负载的参数分析了不同参数的容性负载对漏波天线辐射特性的影响。该技术具有结构简单、低成本、易小型化等特点,可以集成到各种无线通信系统和雷达阵列中。