一种小型化五频段可重构蝶形天线的设计

提出了一种新型多频段可重构天线.该天线采用小型平面蝶形结构,尺寸为35.0mm×38.0mm×1.6mm,由U型馈电带线、矩形寄生单元和接地面构成.通过调节馈电带线的长度和选择寄生单元,改变天线的局部结构和表面电流分布,从而获得不同的工作频段.该天线可在1.94～2.22GHz、2.32～2.54GHz、3.08～3.78GHz、3.63～4.83GHz、4.82～6.85GHz五种频段之间实现可重构,覆盖了主要的无线通信系统工作频段,各个状态具有良好的全向辐射特性和较高增益.因此,具有较大的实用价值.     

卫星导航终端的小型化方形四臂缝隙螺旋天线

设计了一种卫星导航终端的小型化四臂缝隙螺旋天线。天线为方形柱状结构,四条缝隙螺旋臂印制在介质基板外表面,馈电网络印制于介质基板内表面进行耦合馈电;馈电网络为弯折的微带线结构,并延伸至天线底部实现同轴馈电。天线尺寸为23.6 mm×23.6 mm×53.0 mm,实测结果表明,|S11 |≤-10 dB 的阻抗带宽为7.63%(1.512~1.632 GHz),轴比≤3 dB 的圆极化带宽为3.35% (1.556~1.609 GHz),在北斗B1频段中心频率(1.561 GHz)和GPS L1 频段中心频率(1.575 GHz)处增益分别达到4.31 dBi 和4.84 dBi。该天线采用缝隙螺旋结构,并通过简易的馈电网络耦合馈电实现螺旋天线的圆极化,结构小巧简单,适合批量生产,可应用于卫星导航系统终端设备。     

一种小型平面超宽带天线的设计与实现

提出了一种新颖的小型平面超宽带天线。该天线由矩形微带天线的基本结构演变而来,为获得超宽带频率特性,设计时辐射单元下端采用了渐变结构,金属底板使用缺陷地结构。对天线的反射系数、方向图及增益进行了仿真计算和优化设计,实测结果为:天线的工作频段为3.1~13.0 GHz(S11<-10 dB),增益大于1 dB,具有良好的超宽带特性和全向辐射特性。     

一种新颖小型共面波导馈电的超宽带天线设计

设计了一种新颖小型共面波导馈电的喇叭形超宽带天线,接地面不同于传统矩形而采用接地面围绕辐射体两侧向顶部延伸的方式,并且靠近馈线的接地面使用两阶阶梯凹槽,利用仿真软件仿真优化辐射体和接地面的结构参数,天线加工后的尺寸为27 mm×30 mm×1.6 mm,实测阻抗带宽为2.5～12.0 GHz,在3.1～10.6 GHz范围内基本呈全向性,并且具有较稳定的增益,约为2.5 ～ 6.0 dBi.     

一种小型的“Y”形超宽带天线

提出了一种以微带线馈电的小型"Y"形超宽带天线,尺寸为30 mm×30 mm。天线由"Y"形辐射贴片,双"8"字形谐振片以及带矩形槽的接地面三部分构成。利用三维电磁仿真软件对天线的回波损耗、增益、方向图等参数进行了仿真,达到电压驻波比(VSWR)<2的频带范围为3.06~13.89 GHz,频带宽度达到了10.83 GHz,并且天线显示出较好的全向辐射特性,天线的结构简单,易于制作,可用于超宽带通信系统。     

一种共面波导馈电的缝隙型超宽带天线

针对超宽带通信系统,提出一种小型超宽带天线,可以应用于终端设备。天线类型为共面波导馈电的缝隙型,缝隙结构为一矩形与一圆形组合而成,馈电结构与缝隙结构相似。天线的面积为22 mm×27 mm,印刷在厚度为0. 5 mm的FR4衬底上. 通过软件仿真分析了天线的工作原理以及尺寸对带宽的影响,仿真结果显示天线的带宽在不同的衬底厚度下均能覆盖UWB频段。天线的测试带宽为2.4 GHz~14.4 GHz,在超宽带的工作频段内测试效率超过76% ,测试增益大于2.1 dBi。     

加载矩形贴片的圆形缝隙超宽带微带天线

提出了一种新型的加载矩形贴片的平面印制圆形缝隙小型超宽带微带天线,该天线类似一般的圆形缝隙微带天线,但在圆形缝隙中间加载了一个矩形贴片,从而使得天线在获得超宽带特性的同时又保持了很小的物理尺寸.实验结果表明,该天线的阻抗带宽为2.4 GHz～12 GHz,达到了5倍频程,同时自身物理尺寸只有35 mm×35 mm,非常适合应用于目前的超宽带无线通信系统.     

具有两块非对称接地面的高紧凑型超宽带天线

针对超宽带无线通信的应用,提出了一种新颖的具有两块非对称接地面结构的紧凑型超宽带(Ultra-Wideband,UWB)天线.本设计采用半椭圆辐射单元和两块非对称接地平面结构,以获得较宽的工作频率和较小的几何尺寸.对影响天线性能的主要几何参数进行了研究和优化并对所设计天线进行了加工制作与测量.测试结果表明:反射系数S11小于-10 dB时,所设计天线的工作频率覆盖3～12 GHz的范围,满足标准UWB带宽(3.1～10.6 GHz)的要求,且平均增益达到4.5 dBi天线具有较小的几何尺寸,仅为14 mm×18 mm=252 mm2.     

一款多频段小型单极子天线的设计

设计了一款多频段小型宽带单极子天线。采用Ansoft公司的HFSS13电磁仿真软件,对天线进行了仿真及优化,天线尺寸为39mm×29mm×1.7mm,该天线在多个频率点上谐振。仿真结果表明,该天线参数S11≦-10 dB,天线和馈线匹配的很好,覆盖了LTE2300,LTE2500和WLAN的2.4/5.2/5.8 GHZ及WiMAX的2.5/5.5 GHz的工作频段,适于目前的超薄智能手机。     

一种CPW-fed的双陷波超宽带天线的设计

设计了一种小型双阻带超宽带天线.天线采用共面波导(CPW)馈电的地板结构,地板由两个半椭圆构成,从而实现了超宽带天线及小型化.通过开双U型缝隙实现了双阻带特性,阻带带宽分剐是650 MHz和590 GHz.天线实物测量结果表明,天线驻波比<2的带宽为2.97～12.75 GHz,在整个频段内天线增益较高,同时方向图全向...     

新型定向超宽带天线

基于圆片单极天线是一种结构简单的超宽带天线,研究了一种新型的超宽带天线,它将4个圆片单极天线垂直交叉放置作为馈源并采用平板反射面,实现定向以及双极化或圆极化特性。分析了2种变形形式:将平板反射器换为抛物面反射器,实现高增益特性;将圆片振子变形,实现更宽的低频端阻抗带宽。通过电磁仿真软件,计算了天线的S参量和辐射方向图随频率的变化规律。分析表明文中的天线对于传统的圆片单极天线有了有效的改进,实现了超宽带、定向辐射、双极化、圆极化、高增益等不同的特性,它们在卫星通信和移动通信中具有良好的应用前景。     

一种宽带宽角双极化相控阵天线单元研究

设计了一种宽带宽角双极化相控阵天线单元,该天线单元采用指数渐变开槽天线形式,并设计了金属匹配柱安装在双极化天线单元之间,保证了开槽天线的接地连续问题。依次给出了该双极化天线单元的仿真设计、阵列样机的性能测试,从仿真和测试结果中可以看出,该双极化天线在3倍频程带宽内具有良好的匹配和辐射特性,并且能实现大角度二维扫描。该双极化天线单元具有宽频带、体积小、结构简单等特点,适于用作宽带宽角扫描相控阵天线的阵列单元。     

宽带移动通信系统中的多天线分集结构

针对宽带移动通信系统，研究了一种结合Rake接收的任意天线数目的分集结构，导出了误码率的闭式解。数值计算结果表明，这种结构可以明显地改善系统性能。     

Parallel particle swarm optimization and finite- difference time-domain (PSO/FDTD) algorithm for multiband and wide-band patch antenna designs

This paper presents a novel evolutionary optimization methodology for multiband and wide-band patch antenna designs. The particle swarm optimization (PSO) and the finite-difference time-domain (FDTD) are combined to achieve the optimum antenna satisfying a certain design criterion. The antenna geometric parameters are extracted to be optimized by PSO, and a fitness function is evaluated by FDTD simulations to represent the performance of each candidate design. The optimization process is implemented on parallel clusters to reduce the computational time introduced by full-wave analysis. Two examples are investigated in the paper: first, the design of rectangular patch antennas is presented as a test of the parallel PSO/FDTD algorithm. The optimizer is then applied to design E-shaped patch antennas. It is observed that by using different fitness functions, both dual-frequency and wide-band antennas with desired performance are obtained by the optimization. The optimized E-shaped patch antennas are analyzed, fabricated, and measured to validate the robustness of the algorithm. The measured less than - 18 dB return loss (for dual-frequency antenna) and 30.5% bandwidth (for wide-band antenna) exhibit the prospect of the parallel PSO/FDTD algorithm in practical patch antenna designs.     

Capacity scaling and spectral efficiency in wide-band correlated MIMO channels

The dramatic linear increase in ergodic capacity with the number of antennas promised by multiple-input multiple-output (MIMO) wireless communication systems is based on idealized channel models representing a rich scattering environment. Is such scaling sustainable in realistic scattering scenarios? Existing physical models, although realistic, are intractable for addressing this problem analytically due to their complicated nonlinear dependence on propagation path parameters, such as the angles of arrival and delays. In this paper, we leverage a recently introduced virtual representation of physical models that is essentially a Fourier series representation of wide-band MIMO channels in terms of fixed virtual angles and delays. Motivated by physical considerations, we propose a D-connected model for correlated channels defined by a virtual spatial channel matrix consisting of D nonvanishing diagonals with independent and identically distributed (i.i.d.) Gaussian entries. The parameter D provides a meaningful and tractable measure of the richness of scattering. We derive general bounds for the coherent ergodic capacity and investigate capacity scaling with the number of antennas and bandwidth. In the large antenna regime, we show that linear capacity scaling is possible if D scales linearly with the number of antennas. This, in turn, is possible if the number of resolvable paths grows quadratically with the number of antennas. The capacity saturates for linear growth in the number of paths (fixed D). The ergodic capacity does not depend on frequency selectivity of the channel in the wide-band case. Increasing bandwidth tightens the bounds and hastens the convergence of scaling behavior. For large bandwidth, the capacity scales linearly with the signal-to-noise ratio (SNR) as well. We also provide an explicit characterization of the wide-band slope recently proposed by Verdu. Numerical results are presented to illustrate the key theoretical results.     

The multiple sweep method of moments (MSMM) design of wide-bandantennas

This paper presents the use of the multiple sweep method of moments (MSMM) in the design of electrically large wide-band antennas. The MSMM is an O(N²) recursive method for solving the large matrix equations which arise in the method of moments (MM) analysis of electrically large bodies. Although the MSMM is a frequency-domain solution, it has a time-domain interpretation. The main point of this paper is to show that this time-domain interpretation can be used to identify the location and magnitude of points of current reflections, thus making the MSMM a useful tool for the analysis and design of wide-band antennas. The method is applied to the three-dimensional (3-D) problems of a long dipole antenna with a reactive load in the center of each arm and a TEM horn antenna with a bend     

低成本有源相控阵天线研究

研究了有源相控阵天线的低成本设计思路和数字技术新方法。首先详细地分析了有源相控阵天线的系统构架和成本组成;然后从系统总体的角度,探讨了低成本数字阵列相控阵天线设计方法;最后提出了采用宽带宽角扫描的可重构设计技术来降低有源相控阵天线的成本。提出的有源相控阵天线低成本设计新方法具有很好的工程实用价值和科学意义。     

UHF天线的小型化分析

针对超高频机载合成孔径雷达天线小型化、高增益和宽频带的问题,分析了短背射天线缩小背腔的增益损失.根据pottel 推算的公式,计算了馈源反射盘遮挡的增益损失.提出了用一种由宽偶极子构成的H型天线二元阵来取代短背射天线中的引向结构.指出了这种结构不仅能够提高天线增益、展宽频带还能缩小天线结构.比较了国内外小型超高频合成孔径雷达天线的结构.研究表明,利用宽偶极子和微带组阵能为有限平台提供重量轻、结构小、增益高和宽频带的超高频合成孔径雷达天线.     

Antenna effects on indoor obstructed wireless channels and a deterministic image-based wide-band propagation model for in-building personal communication systems

In this paper, the effects of antenna pattern and antenna polarization on indoor obstructed (OBS) wireless channels are investigated experimentally. Our results show that linearly polarized (LP) directional antennas are more effective in combating multipath components than other types of antennas in OBS channels. The measurement results are verified with a deterministic wide-band propagation model based on image theory that takes into account the effects of building geometry, antenna pattern, and antenna polarization. Preliminary prediction results show that the propagation model holds promise for accurate and efficient in-building wireless channel prediction.     

快速PO-MoM技术分析电大载体线天线宽带特性

PO-MoM混合方法是研究电大尺寸载体上天线特性的有效方法。在应用PO-MoM分析复杂载体上天线宽频带电磁辐射问题时,由于需要在间隔很小的多个频率点进行填充阻抗矩阵的运算,计算过程耗时多,效率低。本文采用阻抗插值技术,通过构造有理插值函数来快速计算PO-MoM中的阻抗矩阵,并在迭代求解方程过程中采用了一种近场预条件技术,节省了计算时间,提高了计算效率。采用上述快速技术计算了垂直安装于平板的单极子天线和星载螺旋天线的宽带特性,并探讨了阻抗矩阵插值技术实现过程中一些参数的选取的问题。数值结果表明,结合阻抗插值矩阵插值技术并使用预条件技术的PO-MoM可以快速有效地分析大型复杂载体上天线的宽频带特性。