一种双频段圆极化阵列天线

文章将宽带单极化Vivaldi天线正交排列,通过圆极化电桥馈电,构建双频段圆极化阵列天线的基本辐射单元。利用遗传算法优化圆极化基本辐射单元的曲线特性、开槽宽度等影响电性能的主要结构参数,使其阻抗带宽及轴比带宽满足双频段工作的特性。根据相控阵天线理论,将基本辐射单元按矩形栅格排布得到圆极化阵列天线。仿真结果显示该圆极化天线在双频段内满足轴比及波束覆盖要求。该圆极化阵列天线对双频段圆极化阵天线的设计具有很好的指导意义。     

任意锥角有限长双锥天线电磁特性的仿真研究

运用基于有限元法的HFSS电磁场仿真技术，对任意锥角有限长的双锥天线的电磁特性进行数值研究，得到了包括对称双锥、不对称双锥、盘锥等不同类型锥体天线的阻抗特性和远区场辐射特性，特别是宽锥角下的宽频带特性等。计算结果与实验值及其它理论数据较好地吻合，表明了电磁场数值仿真技术在天线设计中的广阔应用前景。     

宽带低副瓣单脊波导裂缝阵天线设计

本文提出了一种单脊波导裂缝阵天线的改进设计方法。首先分析了单脊波导上孤立缝隙导纳随脊参数的变化特性,据此合理选取脊波导参数;然后根据Elliott 等提出的脊波导缝隙阵设计方程对辐射阵面的缝参数进行初步设计;最后根据各缝隙口面近场分布,优化缝隙的偏置和长度,以消除互耦、边缘绕射等因素对天线副瓣电平的影响。为了验证方法的有效性,设计了一个八元单脊波导裂缝阵天线,仿真结果表明天线驻波带宽约为9.5%（VSWR<1.5）,副瓣电平在-25dB 以下,与已有文献相比均有较大改善。     

赋形双偏置天线口面场分布函数研究

针对目前关于双偏置反射面天线的无遮挡形式口面场分布函数的研究较少的情况,研究了赋形双偏置天线的几何参数变化对口面场分布的影响,进而深入分析了口面场分布对辐射方向图的影响。针对平方公里阵天线(Square Kilometer Array,SKA)高效率低旁瓣的要求,提出了一种改进型余弦口面场分布函数。计算结果表明,天线第一旁瓣电平低于-20 dB,天线效率高于85%。     

同轴共线阵天线分析及在干扰查找中的判别

同轴共线阵天线是一种广泛用于雷达、通信等领域的高增益全向天线.本文通过对该天线进行仿真,结合天线增益图和微波链路计算公式,得出与发射源不同距离、仰角的接收点电平值大小,最后给出徒步查找干扰源的建议.     

闪电电磁脉冲卫星接收天线设计初步探索

针对卫星轨道闪电电磁脉冲(LEMP)的信号特征以及接收环境的限制，提出了卫星轨道接收LEMP的天线设计参数，并据此设计了对称振子天线和对数周期振子阵天线。计算出了两种天线的辐射阻抗，输入阻抗，增益曲线，驻波比等参数，还给出了对数周期振子阵天线的各参数曲线。最后对两种天线进行了比较。对称振子的特点结构简单适合于当前应用。对数周期天线的接收性能优于对称振子天线，更适合于专门的电磁脉冲探测试验卫星。     

基于X波段的高功率圆极化反射阵列天线全波分析研究

传统圆极化反射阵列天线分析方法对天线辐射特性等方面分析的不足,导致在天线全波分析时精度较低,为此,提出了基于X波段的高功率圆极化反射阵列天线全波分析方法.首先研究圆极化反射阵列天线的工作原理,采集相关参数,然后根据参数进行反射阵列天线相位分布、辐射特性、口径效率和单元间距四个方面进行分析.通过仿真实验测试设计阵列天线的...     

新型舰载超短波宽带天线

采用双锥组合变形、多端馈电和套筒结构匹配等技术设计了一类用于舰载超短波通信的小型宽带天线.通过反复实验调整和优化,给出了天线的设计形式和尺寸.在15倍频以上的频带范围内,天线的VSWR基本低于2.5,辐射特性为水平面全向、俯仰面侧射,而尺寸远小于同样用途的传统笼锥类天线,因而具有较大的应用价值.     

双锥中波小天线在云南中波台的应用

双锥中波小天线是一种实用型发射天线,适用于50kW以下的中小功率发射台.文章简要介绍双锥中波小天线的设计原理、物理特性及在云南省中波台的首次成功应用,为中波台站铁塔天线更新改造提供一定的经验启示.     

X波段圆极化透射阵天线

设计了一种具有极化转换功能的圆极化透射阵天线单元。该单元具有3层结构,包括线极化接收贴片、地板和圆极化辐射贴片,通过旋转圆极化辐射贴片来实现相位补偿。采用该单元设计了一种具有极化转换功能的圆极化透射阵天线,并对其进行了仿真。仿真结果表明,在10 GHz处天线的增益和口径效率达到最高,分别为24 dBi和31%,天线的3 dB增益带宽为9%(9.6～10.5 GHz)。与一般的透射阵天线相比,该透射阵的焦径比仅为0.33,具有剖面低的优点。对该天线进行了加工和测试,测试结果与仿真结果基本吻合。     

Correlation and channel capacity of MIMO systems employing multimode antennas

A novel way of exploiting higher modes of antennas as diversity branches in multiple-input-multiple-output (MIMO) systems is introduced. Essentially, antennas employing multiple modes offer characteristics similar to an antenna array, through multiple modes and using only a single element. The physical mechanism that yields different received signals is the fact that each mode has a different radiation pattern. Analytical expressions for the correlation between signals received by different modes are presented for a biconical and a circular microstrip antenna that employs higher order modes. It is found that the correlation is low enough to yield a significant diversity gain. Furthermore, the channel capacity of a MIMO system using a multimode antenna, i.e., an antenna employing multiple modes, is found to be comparable to the capacity of an array. Since only one element is needed, the multimode antenna offers several advantages over traditional arrays, and is an interesting antenna solution for future high capacity MIMO systems.     

A biconical multibeam antenna for space-division multiple access

The biconical antenna is well known as an easy to build broad-band antenna with omnidirectional radiation. In this paper, the biconical antenna is modified for selective radiation in the azimuth direction. By enlarging the diameter of the coaxial feed to the biconical antenna, a set of higher order modes can be excited. In addition to the angle independent TEM mode, higher order TE-modes are also allowed for propagation, which result in an angle-dependent far-field pattern. Several features of this multimode excitation are of interest. Applying multiple input feed connectors allows simple rotation of the antenna beam by switching or, when independently operated, transmission and reception for communication in different angular directions for real-time space division multiple access (SDMA). As with conventional antenna arrays, adaptive pattern synthesis can also be realized by using multiple input feed connectors in combination with an appropriate amplitude and phase shifting network. The antenna allows an extremely flexible design of its characteristics at low cost, both requisites for SDMA communication     

一种新型单层宽带微带反射阵天线设计

针对微带反射阵天线带宽窄的问题,提出了一种新型线极化双谐振宽带"蝴蝶"形单元结构,详细描述了单元结构设计步骤,研究了不同基板以及不同结构参数对单元相位曲线的相移范围、平滑度以及谐振点位置的影响。仿真测试表明,该单元结构能够在5.5-7GHz带宽内具有良好的相位特性曲线。对36个"蝴蝶"形单元组件测试表明,其在20%带宽内辐射效率达到40%以上,最大辐射方向上交叉极化电平小于-30dB。此外,"蝴蝶"形单元结构类似于"十"字形单元结构,有利于进一步扩展实现多频带、多波束反射阵天线设计。     

改进的GPS抗干扰自适应天线阵性能研究

文章提出了一种用于GPS接收机的新型抗干扰自适应天线阵,并给出了对其方向图和输出信干噪比的仿真过程.比较了在相同的信号环境时,该天线阵与常用的均匀直线阵、等间隔圆形阵的性能.结果表明,使用该自适应阵可以改善天线阵的方向图,提高输出信号干扰噪声比SINR,增强接收机的抗干扰能力.     

Photodiode-integrated microstrip antenna array for subterahertz radiation

The radiation characteristics of subterahertz (sub-THz) electromagnetic waves emitted from an antenna array integrated with photodiodes are investigated. The element of the fabricated array antenna was a 300-GHz microstrip antenna integrating a uni-traveling carrier photodiode. It was observed that the beamwidth of a 3 /spl times/ 1 antenna array is about half that of the single microstrip antenna. We also confirmed that the radiation direction changed by 20/spl deg/ when 2/spl pi//5 of phase difference was added to the input optical signal for each antenna element. These results demonstrated that sub-THz waves emitted by each element of the array were coherently superimposed and the power combining of the sub-THz radiation occurred in the microstrip antenna array. The measured output power of each radiation element is about 120 /spl mu/W, and a total output power of 1 mW can be estimated for a fabricated 3 /spl times/ 3 array in an ideal radiation condition.     

端射阵机载雷达杂波建模与杂波特性分析

端射阵天线是指波束指向垂直于阵列法线方向的一类特殊雷达天线,由于其具有低剖面和强定向辐射特性,因而特别适合用于机载雷达的补盲。首先,以均匀端射线阵为阵元组建了端射阵列天线,并在端射阵机载雷达几何模型的基础上对端射阵天线的方向图特性进行了分析;然后,进一步构建端射阵机载雷达的杂波回波数学模型;最后,对端射阵机载雷达的杂波空时谱以及在不同情况下的杂波距离-多普勒谱进行了仿真分析,并与传统侧射阵机载雷达的杂波谱进行了比较。理论与仿真结果表明:所建端射阵空时二维杂波模型是合理的,可为下一步开展端射阵机载雷达空时自适应杂波抑制方法的研究提供数据来源。     

Characteristics of the wire biconical antenna used for EMCmeasurements

The characteristics of a wire biconical antenna that determine its antenna factor were computed by using the method of moments code NEC-2. A fairly extensive validation exercise was conducted from which a suitable computer model was derived. The input impedance, gain, and radiation patterns of the antenna were computed for special cases where the biconical antenna is used above a conducting ground plane for open-field EMC (electromagnetic compatibility) testing. The effects of height above the ground plane and polarization of the antenna on these parameters were found and the antenna factor was corrected for them. The current distribution along the antenna elements was also examined, and it was found that significant pattern distortion can occur at some frequencies when a horizontal wire biconical antenna is used close to the ground. These results will allow this broadband antenna to be used with confidence in applications where previously only resonant dipoles were specified     

Performance enhancement of a compact wideband patch antenna array using EBG structures

In this paper, a compact wideband linear microstrip phased array antenna (MPAA) is proposed. To reduce the size of MPAA, a compact wideband aperture coupled microstrip patch antenna (MPA) is utilized as array element. Size reduction of the array element is performed through incorporating an interdigital capacitor (IDC) in the patch and a metamaterial (MTM) unit cell close to slot in the ground plane of the antenna. By cutting two vertical slits from the slot, further compacting of the slot in the ground plane of array element is obtained. By this technique dimensions of the patch and slot are reduced by 12.9% and 12.2%, respectively. Furthermore, dimensions of the MPAA are reduced through decreasing the spacing between array elements causing the antenna performance degradation. To overcome this shortage and improve the radiation characteristics of the proposed MPAA, an electromagnetic bandgap structure (EBG) is utilized. The effect of implementing EBG cells on the reflection coefficient of the elements in the MPAA during beam scanning is studied in details. The maximum measured gain, bandwidth and cross-polarization level of the fabricated MPAA are 13.3 dBi, 24.4% and −40 dB, respectively making it a good candidate for monopulse tracking radar applications. The measurement results confirm the simulation results.     

渐变巴伦馈电的超宽带天线单元及阵列研究

为了满足超宽带电子系统对天线的需求, 研究了强互耦超宽带天线单元及阵列.首先设计了能够满足强耦合线极化的天线单元, 然后研究了超宽带相控阵天线阵, 设计了10×10天线单元组成的阵列.以此为基础, 利用高频电磁场仿真软件在二维周期环境中模拟了无限大周期阵列.结果表明, 在满足尺寸约束的前提下实现了二维周期边界下超宽带阵列的功能要求, 同时, 解决了强互耦效应下超宽带无限大偶极子相控阵进行全阵列仿真耗时极多、难度极大的问题.为了解决阵列单元如何有效馈电的问题, 在分析了天线单元结构设计的基础上, 研究了渐变结构巴伦的馈电特性, 并将这种馈电结构与上述强耦合超宽带天线单元相结合, 对单元结构和馈电方式进行了优化, 实现了超宽带馈电的效果.加工了天线阵列并在微波暗室中对不同频点进行了测试, 测试结果与仿真结果吻合.从测试结果可以看出, 主平面辐射方向图在不同频点内的最大扫描角波束峰值增益均大于5 dBi, 最大达到20 dBi, 满足设计要求.说明所设计的阵列天线能够应用于实际微波系统中.     

基于GEMS对Ku波段螺旋阵列天线的设计优化

详细阐述平面螺旋天线阵列,利用其具有效率高、旁瓣低和受环境等影响小等优点改善其整体性能。选择小螺旋作为Ku波段的螺旋阵列天线的辐射阵元,利用基于FDTD算法的GEMS软件仿真,调节螺旋参数满足天线设计指标,借助仿真结果确定天线阵列的几何参数,并对其进行测试。通过调试得到优化的结果,基于仿真结果与实测结果进行分析加工和重设计,以组成更大的天线阵列,满足实际需要。