Transparent and conformal wheel-shaped fractal antenna for vehicular communication applications

In this article, a low cost, compact conformal antenna is proposed for vehicular communications applications. The concept of fractal geometry is applied in this design to make the model more attractive in its appearance as well as to attain desired bands in the vehicular communication spectrum. It is fabricated on a transparent and flexible poly vinyl chloride material of size 55 mm × 40 mm × 3 mm. The proposed antenna is intended to operate in GSM-1800/1900, Digital Communication System (DCS-1800), Personal Communication Service (PCS-1900), Universal Mobile Telecommunications System (UMTS), Long-Term Evolution (LTE2600), Industrial, Scientific, and Medical radio band (ISM 2.4G), Wireless local area network (WLAN), Bluetooth, World Interoperability for Microwave Access (WiMAX), IEEE802.11p protocol based Vehicle-to-everything, Dedicated short-range communications (DSRC) and Wireless Access in Vehicular Environments (WAVE) communications bands. The prototype of the antenna in its planar and conformal versions exhibit the wideband characteristics and their measured results show good agreement with that of obtained simulation results. The virtual analysis of platform mounted characteristics of the proposed antenna at two different locations of the vehicle (vehicle roof-top and on side-view mirror) are performed in ANSYS Savant simulation tool and the corresponding far-field radiation performance is characterized.     

液晶嵌入电调谐频率可重构双频天线设计

为了提高可重构天线的频率调谐范围,设计了一种液晶嵌入电调谐频率可重构双频天线.对液晶嵌入取向层处理方法、封装方法、电调谐介电特性测试原理与方法进行了研究.采用三层堆叠方式设计了液晶天线结构,在馈电微带下方填充液晶,利用液晶材料的电控特性改变天线的电特性,从而实现双频可调谐.分析了液晶天线寄生枝节尺寸、矩形微带馈线矩形槽...     

A multi-layered dual-band on-body conformal integrated antenna for WBAN communication

This article presents a dual-band, multi-layered on-body conformal metamaterial (MTM) integrated antenna for Wireless Body Area Network (WBAN) communication. The frequency bands range from 3.2 GHz to 3.5 GHz and 3.9 GHz to 4.3 GHz. A zero-reflection-phase based MTM comprises of the 2 × 2 array of H-shaped unit-cell is installed beneath the monopole antenna to suppress the back radiations, and enhance the gain. The characterization of the unit-cell is done in terms of its reflection and transmission characteristics, refractive index, and material characteristics. The integration of the MTM brings down the peak 1-g-averaged SAR to 0.174 W/kg and 0.207 W/kg at the respective bands of the conformal configuration for a body-antenna separation of 1 mm. The proposed configuration proffers peak realized antenna gain of 4.54 dBi and 4.71 dBi, and Front to Back Ratio (FBR) of 11.79 dB and 12.98 dB at the respective frequency bands. The performance of the proposed antenna is rigorously analyzed against structural deformation, operating frequency, gain, and FBR. The measured performance of antenna agrees well with that of simulated results.     

A quad-polarization and frequency reconfigurable square ring slot loaded microstrip patch antenna for WLAN applications

In this paper, a novel polarization and frequency reconfigurable microstrip patch antenna which can switch between vertical and horizontal linear polarizations, left hand and right hand circular polarizations at two WLAN frequencies is presented. The orthogonal linear polarizations are achieved by a square microstrip patch antenna fed by two ports on adjacent sides. By introducing corner truncated perturbation on opposite corners of right diagonal of a square patch, orthogonal circular polarizations are achieved. By controlling the bias voltage of two PIN diodes loaded at perturbed corners, a single structure can achieve quad polarization states. Furthermore, by superimposing a square ring slot into the corner truncated square patch and incorporating four PIN diodes into the square ring slot, quad polarization are achieved at dual frequencies. Simulated and measured results indicate that the antenna can achieve quad polarization at two WLAN bands (5.15–5.35 GHz) and (5.75–5.85 GHz). The proposed antenna is simple, has low profile and can be scaled easily for other frequencies.     

基于二维微波成像的共形天线RCS提取方法

二维微波成像技术是一种有效诊断雷达目标散射点强度和空间分布的手段。机载共形天线因与机体表面成为一体,常规测试手段难以确定其RCS贡献。基于二维微波成像技术,分离和提取出了装机状态下共形天线的反射率分布,通过二维空间像与二维空间谱之间的波谱变换获得了共形天线的二维空间谱信息,经过直角坐标域至极坐标域的插值获得了对应频率和角度的散射信息,再对定标球进行同样的处理,最终标定出共形天线的RCS贡献。实验结果表明了该技术的有效性。     

多输入多输出可见光通信的天线布局研究

通过改变LED及光电探测器(PD)的 空间分布,得到不同的天线布局,同时通过改 变LED间距dTX、发射端和接收端平面的高度差h等条件,得到了不同的信道传输矩阵H,仿 真分析了以上各种情况下的室内可见光通信系统(VLC)的性能。结果表明,影 响VLC性能的关键参数包含最小欧式距 离dmin和行列式Det(H)。根据系统的关键 参 数,将天线布局分为圆形布局和格点布局两类,圆形布局是指所有LED或PD均 匀地分布在一个 圆上,而格点布局是指所有LED或PD均分布在二维平面中的格点上。仿真结果表明,当dTX变化时,在采 用圆形布局的系统中,行列式Det(H)是影响误码率(BER)的关键因素 ;在采用格点布局的系统中,dmin和Det( H)均是影响系统误码率的关键因素,但在d TX的一定范围内dmin是决定系统性能的关键因素 。而当h发生变化时Det(H)是影响系统性能的 关键因素。     

天线布局对于MIMO可见光通信的影响

针对多输入多输出(MIMO)的室内可见光 通信(VLC)系统,通过改变发光二极管(LED)及 光接收机的空间分布,分析了天线布局对于系统性能的影响。VLC系统采用基于朗伯辐射 的信道模型, 使用常见的重复编码(RC)、空间复用(SMP)和空间调制(SM)3种MIMO技术,分析了两 种系统。第1种为4×6系统,即发射端的4个LED采用正方形布局,光接收机的6个探测器采用正六边形、 矩形和三角 形布局。仿真结果表明,在室内中心处,对于RC,三角形布局的误码率(BE R)性能最好;对于SMP和SM,正六边形和三角形的性能相近,且优于矩形布 局。在室内非中心处,正六边形是3种技术的最优选 择。第2种为8×8系统,LED和光检测器分别采用正八边形、正方形布局。仿真结果表明, 发送端采用正方形布局时系统性能较好。     

一种基于LCP 的低通集总参数滤波器设计

基于多层高分子液晶聚合物(LCP)技术,采用网络综合法,设计了一款超高频(UHF)低通滤波器。利用三维电磁仿真软件HFSS,进行了高Q值、小体积电容、电感,以及UHF低通滤波器立体结构的设计和优化。采用50 μm 厚度双面覆铜的LCP 基板以及25 μm 厚度的粘合板,结合铜浆垂直互连工艺,进行了低通滤波器多层结构加工。测试结果表明:该低通滤波器截止频率为1 GHz,在0~1 GHz 的通带范围内回波损耗在-10 dB 以下,插损最大为-2.6 dB,在2 GHz 处,带外抑制达到-38 dB,器件尺寸为10.1 mm×3.5 mm×0.197 mm。该研究验证了多层LCP工艺在微波频段内具有较高的集成度。     

Compact body-worn MIMO antenna with high port isolation for UWB applications

This article investigates the mutual coupling reduction of a compact two elements wearable ultra-wideband (UWB) multiple-input multiple-output (MIMO) antenna. The ground plane of the proposed wearable MIMO antenna structure consists of three connected square ring-shaped stubs and two rectangular slots of narrow height. These ground stubs and slots minimize the mutual coupling effect between antennas and provide high isolation. The suggested MIMO antenna functions from the 1.87 to 13.82 GHz frequency spectrum covering WLAN (2.4–2.484 GHz), UWB (3.1–10.6 GHz), and X band (8–12 GHz) with 152.32% fractional bandwidth. It sustains port isolation above 27 dB throughout the 2 to 13.82 GHz frequency band. Inside the whole working frequency band, the suggested antenna offers a tiny envelope correlation coefficient (ECC < 0.098), greater diversity gain (DG > 9.93 dB), minimum channel capacity loss (CCL < 0.32 bits/s/Hz), and slight magnitude variation in mean effective gain of antenna ports (< 0.1 dB). The recommended antenna yields a SAR level below the designated threshold (<1.6 W/kg), affirming its suitability for body-worn applications. The designed MIMO antenna structure has an overall volume of 32 × 48 × 1.5 mm³.     

天线振动对数字无线通信系统影响机制研究

振动会造成天线相对位置变化,产生干扰信号,导致通信质量下降.基于振动天线辐射理论模型,定量分析了四进制相移键控(quadrature phase shift keying,QPSK)系统天线振动对通信性能的影响,推导了QPSK系统天线在振动条件下系统误符率(symbol error rate,SER)公式,并通过计算机...     

实用型等离子体天线的研制与测试

为了解决等离子天线增益低、噪声大、体积大、质量重、功耗高等问题.在天线增益取得突破性进展的基础上,通过重新设计天线激励源和各主要腔体等措施,研制了一款新型等离子体天线样机,该样机尺寸小、质量轻,并实现了低噪声和较低的功耗.在外场测试中,该样机达到与金属天线相近的增益水平.     

A novel Ultra WideBand monopole antenna with band-notched characteristics

A simple and compact microstrip-fed Ultra WideBand(UWB) printed monopole antenna with band-notched characteristic is proposed in this paper.The antenna is composed of a square ring with a small strip bar,so that the antenna occupies about 7.69 GHz bandwidth covering 3.11～10.8 GHz with expected band rejection from 5.12 GHz to 5.87 GHz.A quasi-omnidirectional and quasi-sym-metrical radiation pattern is also obtained.This kind of band-notched UWB antenna requires no ex-ternal filters and thus greatly simplifie...     

相控阵结合伺服辅助的车载动中通天线跟踪方法

天线跟踪功能是车载动中通系统( SOTM)提供无线通信能力的前提,相控阵天线能提供较好的跟踪性能,但是存在波束扫描范围有限的问题。为实现相控阵天线全方位跟踪能力,提出了一种相控阵+伺服辅助的方法。给出了算法数据处理流程,并完成了原理样机设计。根据原理样机工作原理给出了跟踪角误差计算公式,测试结果与计算结果相符。测试结果表明：在(57.88~115.76)。/s角速度下,通信链路信噪比损失小于0.5 dB。     

基于柔性LCP基板的SIW带通滤波器设计与实现

液晶高分子聚合物(LCP)以其优异的高频特性而被广泛应用于高频无源器件设计以及封装基板制备.文章利用LCP基板设计并实现了一款结构紧凑、中心频率20 GHz、相对带宽为30％、带内损耗小于2 dB的基片集成波导(SIW)带通滤波器.通过在SIW谐振腔短边垂直方向引入微扰金属通孔,实现了谐振腔主模中心频率从16 GHz上...     

Evolutionary algorithms for optimal synthesis of thinned multiple concentric circular array antenna with constraints

ABSTRACT

The novel implementation of three evolutionary optimisation algorithms, namely quantum particle swarm optimisation (QPSO), teaching-learning based optimisation (TLBO) and symbiotic organism search (SOS) for thinning of multiple concentric circular array antenna with isotropic array elements for the simultaneous optimisation of the sidelobe levels (SLLs) as well as peak directivity is presented in this work. The performance studies as cases 1 and 2 are made with two control parameters: interring radii and number of switched ‘on–off’ elements in each ring. The comparative study of the three algorithms has been carried out using common parameters. Finally, experimental results show that case 2 outperforms case 1 with regard to SLL and directivity. Apart from this, the results of SOS have been shown to be better than the other two state of art meta-heuristic optimisation after comparing their effectiveness based on SLL, peak directivity, mean value, and standard deviation along with best cost. For statistical validation of both cases, t-test has been done for testing the stability of SOS over QPSO and TLBO.     

基于HFSS的多频微带天线分析与设计

设计了一种缝隙多频微带天线。通过在微带天线贴片上加载缝隙改变电流分布,从而实现微带天线的多频谐振。用HFSS软件对其进行仿真分析实现参数的优化设计,在1~6 GHz内得到了3个谐振频率:2.43,4.40和5.27 GHz,其回波损耗分别为:–31.84,–32.82,–29.62 d B。当回波损耗小于–10 d B时,相对带宽分别为:3.29%,1.41%,2.05%。该多频微带天线具有体积小、回波损耗低等优点,可用于无线通讯系统。     

一种开槽的双频段宽带科赫分形天线

基于分形理论设计了一种开槽的双频宽带特性的科赫（以下称Koch）雪花分形天线.天线的结构紧凑,两个工作频段宽覆盖了第二代移动通信数字蜂窝系统(Digital Cellular System,DCS)/个人通信业务(Personal Communication System,PCS)频段、第三代移动通信时分同步的码分多址技术（Time Dicision-Synchronization Code Divcision Multiple AccessTime,TD-SCDMA）频段和全球微波互联接入或无线城域网(Worldwide Interoperability for Microwave Access,WiMax)频段等无线通信频段.同时,天线在各个工作频段内有良好的方向辐射性.天线模型经过二维电磁仿真软件（High Frequency Structure Simulator,HFSS）仿真分析,并对天线的样品进行了实物测量,仿真结果与测量结果有较好的一致性.     

切变聚合物网络液晶光阀

针对向列型液晶光阀响应速度慢的问题,提出了一种工作在可见光波段的切变聚合物网络液晶光阀(SLCLV).通过测定其电光响应,这种切变聚合物网络液晶(SLC)的响应时间可达几个毫秒,比相同条件下的向列型液晶的响应速度提高了一个数量级,而且对厚度依赖性小.通过理论分析,提出了SLC的工作原理,介绍了工作在可见光波段的反射式电寻址SLCLV的制作过程.器件的制作工艺简单,可靠性高.在可见光-可见光图像转换系统中,测得这种液晶光阀的帧频可达500 Hz,分辨率为81p/mm.如果能进一步提高制作工艺,这种液晶光阀在高速光学信息处理方面有广阔的应用前景.     

一种基于聚合物分散液晶的荧光开关研究

利用聚合物分散液(PDLC)关特性并与同化荧光材料的特性相结合,制备出一种新型的、具有荧光效应并且荧光激发可由电场调控的荧光开关.用蓝色LED入射到开关器件,通过调制施加在开关上的驱动电压,当光开关关闭时可阻挡蓝色LED光通过,抑制荧光的产生,当光开关开启时,可在散射光路中探测到明显的荧光产生.实验发现,驱动电压在0～...