大型阵列天线辐射的近似分析

将散射矩阵推广到阵列天线的辐射分析当中,推导出阵列天线辐射计算基础理论公式.该公式综合考虑了天线与馈电系统的失配引起的反射、天线单元之间的互耦效应以及天线单元在阵列当中和位于自由空间的辐射特性的变化.采用算例验证了该计算公式的正确性,根据阵列单元的辐射特点和S参数特点,提出了大型阵列辐射场的近似计算方法.以此为基础采用泰勒馈电设计了副瓣电平低于一30dB的大型阵列天线.     

双阻带特性的超宽带平面宽槽天线研究

本文设计了微带馈电和共面波导馈电的平面宽槽超宽带天线。采用阶梯式过渡微带拓宽了天线的阻抗带宽,分析了开槽大小对天线驻波的影响。槽和馈电单元都采用了由椭圆和矩形构成的混合结构。这两种天线在实现小型化的同时,满足了FCC规定的超宽带标准。文章的最后部分采用寄生条带和贴片开槽的方法,实现了天线的双阻带特性。     

一种宽带低副瓣微带阵列天线的设计

提出了一种X波段宽带低副瓣微带阵列天线的设计方法。在考虑互耦效应的影响下,通过改进微带贴片形状与优化贴片尺寸,有效地改善了天线单元阻抗特性。采用不等幅功分器设计微带形式的馈电网络,得到了16×16元微带阵列天线。设计结果表明,在所要求的9.5GHz~10.5GHz工作频段内,该阵列天线电压驻波比小于1.6,增益大于27.5d B,方位面与俯仰面副瓣电平均优于25d B。     

一种X波段宽带低副瓣微带阵列天线设计

介绍一种新型的x波段宽带低副瓣平面微带阵列天线设计,采用口径耦合馈电的背腔式贴片天线实现了单层微带贴片的宽带工作;采用倒置微带线、低阻传输线、非隔离的T形功分器与双口馈电十字功分器相结合等多种技术手段,弱化了馈电网络的传输损耗、寄生辐射及耦合效应。基于项目需求设计、加工了一套14×14单元天线阵列,测试结果表明,该天线在10．5％的频段内驻波比优于1．5、副瓣电平优于-24．5dB、辐射效率大于55％。     

一种新型2.4GHz频段加载贴片天线的设计

采用在贴片上开槽和加载的方法,设计了一种用于2.4GHz频段无线通信设备、内缩渐变线馈电的新型结构贴片天线.给出仿真设计的性能和多个天线样品的实测输入驻波比曲线和远区辐射特性图,详细研究分析了不同加载条件、不同辐射边尺寸对输入驻波比的影响.实测结果表明,该天线在2.4GHz频段上获得超过15%的相对带宽(VSWR<2),而且尺寸比相应频段的微带贴片天线更加微型化.     

相控阵天线系统散射分析

该文采用S参数分析了有源相控阵天线单元馈电系统模型的接收机负载反射系数.将该反射系数代入阵列天线散射场基础理论公式分析了有源相控阵天线的散射场,将有源相控阵天线的天线模式项散射场分为天线模式反射散射场和天线模式相控散射场进行分析.最后通过一维线阵验证了理论分析结果.该分析方法和分析结果为相控阵天线RCS计算和控制提供了理论指导.     

低RCS宽带磁电偶极子贴片天线设计

该文设计了一种低雷达散射截面(RCS)的宽带磁电偶极子贴片天线,其中印刷在介质板上的金属贴片为电偶极子,3个金属过孔连接辐射贴片与金属地板构成磁偶极子。整个天线采用T型渐变馈电结构同时激励电偶极子与磁偶极子,天线的频带范围为7.81~13.65 GHz,覆盖了整个X波段。实测和仿真结果表明,通过在磁电偶极子贴片天线底面采用开槽技术并优化开槽的形状、大小、位置等变量,在天线工作频带范围内实现了RCS的减缩,最大缩减量达到了17.9 dB,同时天线保持了增益稳定不变,E面、H面方向图一致的特性。     

馈电网络对微带天线阵列时域散射特性的影响

利用时域有限差分(FDTD)方法,研究了入射脉冲分别为水平和垂直极化时,探针馈电和微带馈电两种结构对于微带贴片阵列天线后向散射场的影响.给出了散射场的时域波形以及频谱特征.结果表明:微带天线阵列的每个贴片都通过馈电探针直接端接负载时,阵列的散射场峰值和能量都有所减小;而阵列通过馈电网络进行馈电时,馈电网络末端有无端接负...     

超宽带平面渐变开槽印刷天线阵的实验研究

采用共面波导到槽线的超宽带馈电结构,研制出用于接收阵列的超宽带渐变开槽印刷天线.在外场用示波器测量H面的时域方向图,结果表明:该阵列天线适合于用作实际的超宽带雷达接收天线阵.     

Koch分形与H形开槽相结合减缩微带贴片天线RCS

文中首次将Koch分形与H形开槽相结合应用于微带贴片天线RCS减缩中.设计了一副分形开槽微带天线.与工作在同一频率的矩形微带天线进行了比较,天线增益损失只有0.8 dBi,而天线的谐振峰值却得到了有效控制,天线RCS在带内减缩1.8 dBsm,在带外实现2 dBsm-14 dBsm的RCS减缩.设计天线具有较好的辐射特性和散射特性.     

Sierpinski分形天线特性分析

Sierpinski分形天线的结构具有自相似性,从而天线具有良好的多频带特性。文中主要研究了Sierpinski分形天线频带位置随天线张角和比例因子变化的一般规律,并简要的分析了Sierpinski分形天线阵,绘出了其远场方向图,讨论了其低副瓣特性。     

ETC用5.835GHz微带阵列天线的设计

设计了一种ETC用低旁瓣圆极化微带阵列天线,应用于电子收费(ETC)的路测单元(RSU)。为实现低旁瓣、圆极化的效果,对2个微带天线单元运用旋转与相位补偿的方法进行轴比改进,并以改进后的2单元作为辐射单元制作了一款基于道尔夫-切比雪夫幅度分布的微带天线阵列。经过仿真与实际测量,该天线具有很好的低旁瓣、圆极化的效果。该天线对于ETC系统以及其他类似的天线系统具有很好的理论与实际意义。     

Synthesis of Low and Equal-Ripple Sidelobe Patterns in Time-Modulated Circular Antenna Arrays

In this paper, the time modulation technique is applied into circular antenna arrays with uniform amplitude excitations for the synthesis of ultra-low sidelobe and equal-ripple radiation patterns. The differential evolution (DE) algorithm is adopted to optimize the excitation phases and the switch-on time intervals of each element of the time-modulated circular array (TMCA). Several low-sidelobe patterns synthesized from TMCAs were compared to those of the conventional circular arrays. Numerical results show that the TMCA can be successfully used for the synthesis of low SLLs even if the amplitude excitations are uniform. Supported in part by the Natural Science Foundation of China under Grant No. 60571023, the New Century Excellent Talent Program in China (Grant No. NCET-06-0809), and in part by the 111 project of China (Grant No. B07046).     

2-D periodic leaky-wave Antennas-part II: slot design

The far-field radiation patterns of a two-dimensional (2-D) periodic slot leaky-wave antenna (LWA) are studied. The antenna consists of a two-dimensional periodic array of slots in a conducting plane that is printed on top of a grounded dielectric slab. The antenna is excited by a simple source such as a dipole inside the slab. Reciprocity along with the spectral-domain method is used to calculate the far-field pattern, and the radiation characteristics of the structure are investigated. A comparison between the present periodic slot LWA and a 2-D periodic patch LWA discussed in Part I is given to show the advantages of the slot antenna for certain applications. The slot LWA can achieve high directivity patterns, and a circularly-polarized version of the antenna can achieve good circular-polarization at broadside.     

Microstrip-Franklin Antenna

Phasing stubs are employed to achieve a cophase current distribution in microstrip rectangular patch arrays. This technique, originally proposed for resonant long wire antennas by Franklin, avoids spurious radiation from half-wavelength connecting transmission lines as used in conventional patch antenna arrays. A slot-radiator model is derived to describe the basic radiation mechanism of the resultant new type of antenna and experimental results for the slot radiation resistance are given. The design of a 13-element resonant array for 12 GHz is presented together with measured radiation patterns.     

一种单层贴片式双频双极化滤波天线

设计了一种单层式跨频段双频双极化滤波天线。该天线在同一平面上的高频低频辐射贴片共用一个馈电端口,且均可以在两个垂直方向馈电实现交叉方向的线极化辐射。该天线通过在馈电点与低频辐射贴片之间插入一个低通滤波器,明显提高了高频辐射贴片的交叉极化隔离度。研究结果表明,带滤波结构的天线在两个频率点的反射系数小于-20 dB,4.9 GHz的最大增益大于4.8 dBi,26 GHz的最大增益11.7 dBi,〖JP2〗两个辐射频率的辐射方向图均体现良好的线极化特性,且主极化比交叉极化大20 dBi。该天线可作为未来微波与毫米波共用的5G通信终端天线或5G通信基站的MIMO天线阵元,相关技术和结论对于研制一体化集成的双频交叉极化相控阵天线也有重要参考价值。     

一种实用的相控阵近场诊断新方法

提出了一种相控阵天线近场诊断的新方法.传统的方法要诊断出相控阵天线单元的激励,必须已知阵列单元的方向图和探头的方向图.文中基于相控阵天线的激励、单元方向图、探头方向图和近场测量数据之间的关系,得到了相控阵天线的激励和近场测量数据之间的耦合方程.利用多项式插值,在不必已知单元方向图和探头方向图的情况下,求解出相控阵天线的单元激励.     

A Method of Cross-Polarization Reduction

A method for the reduction of cross-polarized radiation is described. The method can be used for various antenna array systems made up of radiating elements with higher cross-polarized radiation. This solution enables numerous possibilities for selecting the position, the spacing, and the excitation coefficient of any array element. It is even possible to use two different linearly polarized arrays that use the same or different polarizations. Two examples are given: a quarter-wave microstrip antenna system operating in two frequency bands, and a suspended patch array     

Fixed-Beam Frequency-Tunable Phase-Reversal Coplanar Stripline Antenna Array

A fixed-beam frequency-tunable coplanar stripline (CPS) antenna array using the phase reversal technique and varactor diodes tuning is presented. The antenna array is composed of plurality of half-wavelength CPS sections interconnected by phase reversing crossovers. These crossovers have two functions: they serve as the radiators (small dipoles) of the array and also provide their own required in-phase excitations for broadside radiation. Two microstrip-to-CPS transitions for excitation of the balanced input/output antenna array are implemented and compared. A six-element array is demonstrated theoretically and experimentally, with 9.3 dBi of gain for bidirectional radiation and 12.5 dBi of gain for unidirectional radiation using a back reflector. Moreover, shunt varactor diodes are incorporated along the CPS structure to achieve frequency tuning through a bias voltage control while broadside radiation patterns remain fixed. The return loss and the radiation patterns at several frequencies are presented, and up to 50% tuning range is obtained. The proposed antenna array is simple and uniplanar with small lateral size, high radiation efficiency and high directivity. In addition, it uses a very simple biasing circuit with high DC-RF isolation. Its balanced input/output makes it suitable for RF system integration and active integrated antenna design.