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针对低频电磁传输中天线尺寸过大的问题,设计了一种基于三相感应电机的小型化超低频发射天线.电机工作时产生了时变低频电磁场,可作为超低频发射天线.为有效分析其电磁场分布,文章建立旋转磁偶极子数学模型以等效电机内部旋转时产生的磁场.首先,对电机内部磁场和旋转磁偶极子的关系进行阐述,利用麦克斯韦方程组,得到旋转磁偶极子的电磁场分布.其次,通过电磁仿真软件验证旋转磁偶极子的近场分布特性和远场辐射特性.最后,通过实验对电机近场的磁场分布进行验证.仿真和实测结果表明,三相感应电机具有超低频天线的辐射特性. 相似文献
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天线的远场对于研究天线辐射特性具有重大意义,近场测量技术因其能够避免直接测量远场而得到广泛应用,该技术采用近远场变换获得远场,然而,检验该远场的准确性也是很重要的.为了解决此类问题,文中以球面近场测量为例,提供了一种解决方案.该方案主要探讨了球面波模式展开理论,该理论是实现球面近远场变换算法的关键,其将待测天线在空间建立的场展开成球面波函数之和,天线的加权系数既包含了远场信息也包含了近场信息.因此,不仅能够利用近场测量信息获得远场辐射特性,同样能够利用远场辐射特性反推得到近场处电场,这样就能检验由近远场变换算法得到的远场是否准确.文中首先推算得到了近远场变换公式,随后进一步推算得到远近场变换的公式,最后将本文算法计算结果与FEKO测量结果进行比较,二者吻合良好,从而证实了本文两种算法的有效性. 相似文献
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近场直接天线调制(NFDAM)技术是新近出现的一种高安全性宽频带调制技术,它改善了传统调制技术中系统结构复杂、通信的安全性差等特点。应用NFDAM 技术所设计的近场调制型芯片天线能够发射一种与方向相关的信号,所辐射的远场信号由于天线近场电磁边界条件的改变而进行调制,本论文通过在主天线附近放置具有开关的反射器的方式实现改变天线辐射特性,开关的闭合和断开的控制改变反射器的反射特性,从而形成不同组合的天线形式。本文设计完成了一个工作在60GHz 的最简化近场调制型芯片天线,利用CST 电磁仿真软件和MATLAB 软件对天线远场的辐射特性进行了仿真和分析,对近场调制型芯片天线的调制作用及通信的安全性进行了验证。 相似文献
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陈宏 《电子信息对抗技术》2017,32(2)
研究了一种宽带电磁脉冲辐射振荡与辐射方法,基于该方法设计了一种紧凑型宽带电磁脉冲辐射装置.仿真分析与试验研究结果表明,该辐射装置在输入电压为300kV的条件下,可获得131kV的全向远场辐射因子,电压辐射效率大于40%. 相似文献
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圆锥螺旋天线是一种宽频带天线.然而,由于存在色散问题,使得发射的信号发生扭曲,对于加载的宽频带脉冲信号,通过该天线发射出去的并不是与激励相类似的脉冲电磁波,而是一个振荡波.基于时域有限差分法(FDTD)对圆锥螺旋天线进行了仿真,验证了该天线脉冲发射时不同频率分量信号所对应的天线有效作用区域特性,分析了近场和远场的电磁波波形,由此来阐述圆锥螺旋天线的色散与发射特性.仿真得到的结果,对于指导天线设计与相关试验具有一定意义. 相似文献
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针对大型受试设备核电磁脉冲抗扰度试验评估要求,研制了基于Marx发生器脉冲源和横电磁波(Transverse Electro Magnetic,TEM)喇叭天线的可移动、极化方向可调的定向辐射式核电磁脉冲模拟器.实验分析了不同极化方向和终端负载对脉冲波形的影响,确定了定向辐射式核电磁脉冲模拟器的均匀区域.结果表明:辐射电磁脉冲场可用区域为近场区域,随着与口径面距离的增大,峰值场强近似按1/d2衰减,脉冲宽度显著减小;与传输式模拟器相比,辐射式核电磁脉冲模拟器具有更大的均匀区域,更适合大型设备电磁脉冲抗扰度试验. 相似文献
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Low L. Langley R. Breden R. Callaghan P. 《Antennas and Propagation, IEEE Transactions on》2006,54(12):3707-3712
A new printed antenna system mounted in an aperture in the roof of a car is evaluated for broadcast signal reception from 88-108 MHz. Results from simulations on the vehicle are compared with measurements. The overall performance of the antenna is also compared to common types of vehicle antennas, the roof monopole and a glass based antenna. Overall the average gain of the antennas was better than -3 dBi for vertical polarization and -10 dBi for horizontal while the input return loss was generally better than -2 dB before matching sections in the tuners and comparable with common automotive antennas. The antennas in the roof aperture offer an alternative place to mount antennas on automobiles 相似文献
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D. S. Gavva Eugene Medvedev Olena Ivanova E. V. Sharapova 《Radioelectronics and Communications Systems》2018,61(3):94-109
Current-technology different data transmission standards communication systems are commonly built with application of configurable antennas. Non-linear components including in radiating structure of antenna allows to expand the antenna functionability (operating frequency change, modification of the radiation pattern, change of polarization, input impedance, etc.), but also it can result in non-linear effects appear that distort antenna characteristics and transmitted data. In this connection in this paper there are considered actual problems such as methods of numerical analysis of non-linear effects in configurable antennas, specificities of switching components used in antennas, numerical research of influence of voltage-capacity characteristics of radiating structure switch and excitation power on antenna characteristics. Carried out estimated researches allow to obtain general representations and predict nonlinear distortions in configurable antennas caused by used different types switches. 相似文献
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提出了分别采用凹形电极和新叉指形电极的两种光电导天线,其电极产生的静电场电场强度是中间小而周围大,而激光光斑的光强是中间大而周围小,因此提高了衬底的抗击穿能力和光电流。相比于采用传统带状线电极的光电导天线,采用凹形电极的光电导天线产生的光电流提升了62%;相比于采用传统叉指形电极的光电导天线,采用新叉指形电极的光电导天线产生的光电流提升了41%。所设计的两种光电导天线都具有结构简单、便于加工且易与其他提高辐射功率的技术相结合的优点,其在成像、生物传感、通信和光电探测等领域有着重要的潜在应用价值。 相似文献
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新型集成超宽带开槽天线的研制及其应用 总被引:10,自引:1,他引:9
研制出一种用于超宽带短脉宽射和接收的新型集成超宽带槽天线,该天线采用共面波导到槽线的宽带过渡方式馈电,实验结果显示了其高保真的宽带特性及高增益高效益特性。利用所研制的UWB天线建立起超宽超带雷达实验系统,测量几种简单目标特性及涂层目标特性,证明了该种天线可用作实际的UWBR天线。 相似文献
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Wire-antenna designs using genetic algorithms 总被引:1,自引:0,他引:1
There is a large class of electromagnetic radiators designated as wire antennas. As a rule, an inductive process is used to design these antennas. Either an integral equation is formulated or a simulator is used that gives the current distributions on the wires of the antenna, from which the electromagnetic properties of the antenna can then be determined. Once the antenna properties are known, the parameters are optimized, using guides such as intuition, experience, simplified equations, or empirical studies. However, using an electromagnetics simulator in conjunction with a genetic algorithm (GA), it is possible to design an antenna using a completely deductive approach: the desired electromagnetic properties of the antenna are specified, and the wire configuration that most closely produces these results is then synthesized by the algorithm. In this paper, we describe four antennas designed using GAs. The first is a monopole, loaded with a modified folded dipole that was designed to radiate uniform power over the hemisphere at a frequency of 1.6 GHz. The second antenna consists of seven wires, the locations and lengths of which are determined by the GA alone, that radiates waves with right-hand-circular polarization at elevation angles above 10°, also at 1.6 GHz. The last two antennas are modified Yagis. One is designed for a broad frequency band and very low sidelobes at a center frequency of 235 MHz. The other is designed for high gain at a single frequency of 432 MHz. We have built and tested these antennas 相似文献
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FDTD分析探地雷达天线的辐射特性 总被引:4,自引:0,他引:4
探地雷达系统一般采用超宽带短脉冲信号,因而其天线系统必须具有较好的宽带性能。只有几种类型的宽带天线能够用于探地雷达系统中,如电阻加载的蝶形天线、TEM喇叭天线及其变形形式。本文将给出一种新型的探地雷达天线,该天线为置于镜像面上且具有离散指数电阻加载的单偶极子。文中将采用FDTD计算和分析该天线在自由空间和有耗媒质上方时的辐射特性。结果表明,通过选择一定的电阻加载形式,可使天线具有较好的辐射波形,从而能够满足实际探地雷达的需要。最后,通过地下目标散射场的理论结果和实验结果说明了本文所采用方法的正确性。 相似文献
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There is a constant need to reduce the size of antennas without affecting their performance. The method of shorting patches to reduce the physical size of antennas is a common practice. The use of finite ground planes with these types of antennas can have a negative effect on their performance. Here, the introduction of non-planar rings in conjunction with a shorted patch to minimise the negative effects of the finite ground plane resulting in an overall antenna size reduction and an improvement in antenna performance is proposed 相似文献