改进型超宽带Vivaldi天线设计与仿真

在传统Vivaldi天线结构的基础上,设计了两种适用于宽带信号收发系统的改进型渐变槽Vivaldi天线以及同轴馈电型对踵Vivaldi天线,并利用电磁仿真软件HFSS对这两种Vivaldi天线的性能进行优化分析.通过对不同结构Vivaldi天线的对比分析结果可以看出改进型渐变槽Vivaldi天线和同轴馈电型对踵Vivaldi天线在频段、带宽、驻波比等方面均达到宽带传输系统的设计要求.     

Patch Loading Circular Aperture Slot Antennas for Broadband WLAN Applications

This paper proposes a new and simple design for a broadband planar antenna with bi- and uni-directional radiation for WLAN applications. The broadband operation is realized by loading a patch into a circular aperture slot, which is fed by a micostrip line on the other side of the slot. The frequency characteristics and the radiation performance of the antenna were studied theoretically and experimentally. The obtained results show that the proposed antenna can offer effective bandwidth for the two cases in bi- and uni-directional radiation. For the former, more than 75% impedance bandwidth can be obtained whereas for the latter, better than 20 dB front–back radiation ratio can be achieved.Tayeb A. Denidni (M98-SM04) received the B.Sc. degree in electronic engineering from the University of Setif, Setif, Algeria, in 1986, and the M.Sc. and Ph.D. degrees in electrical engineering from Laval University, Qubec City, QC, Canada, in 1990 and 1994, respectively. From 1994 to 1996, he was an Assistant Professor with the engineering department, Universit du Qubec in Rimouski (UQAR), Rimouski, QC, Canada. From 1996 to 2000, he was also an Associate Professor at UQAR, where he founded the Telecommunications laboratory. Since August 2000, he has been with the Personal Communications Staff, Institut National de la Recherche Scientifique (INRS-EMT), Universit du Qubec, Montreal, QC, Canada. His current research interests include planar microstrip antennas, dielectric resonator antennas, adaptive antenna arrays, microwave and RF design for wireless applications, phased arrays, microwave filters, RF instrumentation and measurements, microwave and development for wireless communications systems. Dr. Denidni is a Member for the Order of Engineers of the Province of Qubec, Canada. He is also a Member of URSI (Commission C). He has authored more than 60 papers in refereed journals and conferences.Qinjiang Rao received the Ph.D. degree from Peking University, Beijing, China, in July 1999. Now he is a postdoctoral fellow at INRS-EMT, University of Quebec, Montreal, Canada. Before this term, he even worked as a postdoctoral fellow at Kyoto University, Kyoto, Japan, and University of Calgary, Calgary, Canada, respectively. His research fields focus on antennas, high-frequency electromagnetic simulators, radio wave propagation and scattering. In 1999, he was the recipient of a Post-doctoral Fellowship awarded by the JSPS (Japan Society for the Promotion of Science.)     

基于缝隙效应的几种宽带微带天线的设计

利用缝隙对天线带宽的影响设计了四种宽带微带天线。主要研究了缝隙的形状和大小以及与馈电的距离对天线带宽的影响。首先,宽缝机构可以较大的展宽天线的频带,如果同时配合在贴片上适当的开缝,带宽将进一步展宽;其次,相同缝隙结构的嵌套可使天线同时谐振在很多的频率,从而增加带宽。设计表明这几种微带天线都具有宽带特性,尤其是前两种天线具有超宽带（UWB）的特性,后两种天线的带宽也达到了48％以上。     

Design of Dielectric Grating Antennas for Millimeter-Wave Applications

At theoretical procedure well suited for generating design data on dielectric grating antennas for the millimeter-wave region is presented. The procedure utilizes the effective dielectric constant (EDC) method to determine the phase constant of the leaky modes supported by the antenna structure of finite lateral width. The radiation or leakage constant of these modes is obtained from the relatively simple boundary value problem of dielectric grating antennas of infinite width. For single-beam radiation, the practicably interesting case, the phase and leakage constants completely determine the field distribution in the antenna aperture, from which the directivity gain and radiation pattern are then calculated. The dependence of the antenna characteristics on the dimensions of the radiating structure is presented and discussed for epsilon = 12, the dielectric constant of typical millimeter-wave materials, such as silicon and GaAs.     

超宽带平面天线中实现频带抑制的方法

随着超宽带平面天线的研究和广泛应用,在超宽带天线中实现对其他无线通信设备特别是WLAN设备的干扰抑制成为研究热点。从不同结构的超宽带平面单极子天线实现频带抑制的方法出发,研究实现频带抑制的基本原理和常用方法。研究成果对超宽带天线的设计和频带的抑制具有一定的指导作用。     

高安全等级嵌入式应用的设计考虑

介绍了安全嵌入式系统设计考虑,提出了几种防入侵措施.     

一种宽频UWB平面单极子贴片天线设计

目前超宽带无线通信已成为研究的热点,基于此提出了一种小型超宽带酒杯形单极子天线结构,对地板采用做一对切角形处理,提高了宽频天线性能,对其他参数影响不大。通过数值模拟,天线主抗带宽为3.10～11.45 GHz,覆盖了FCC建议的频段。在辐射方向图E面和H面具有良好方向图稳定性,基本满足了超宽带通信对天线的要求。     

Design Considerations of Broadband Dual-Mode Optical Fibers

We propose and present design data for a new type of graded index fiber which has a profile and radius such that only two mode groups (LP/sub 01/ and LP/sub 11/) propagate and both propagate with virtually identical group velocities. This dual-mode fiber has a core diameter approximately twice that of a conventional step index single-mode fiber. For example, a core diameter of 16.3 mu m is attainable with relative index difference Delta=0.3 percent at 1.25-mu m wavelength. Fabrication tolerances securing a group delay difference below 100 ps/km are given by a power-law profile parameter alpha=4.85/spl plusmn/0.25 and a normalized frequency upsilon=4.45/spl plusmn/0.11. The allowable upsilon-value deviation range to keep the group delay difference within 100 ps/km is about five times as large as that of a step-index fiber, in which group delays of two mode groups are matched. Comparison with a multimode graded-index fiber, with respect to group delay characteristics and bending loss of the dual-mode fiber, are also discussed.     

Dielectric Lens Antennas for Wireless Broadband Communications

Dielectric lens antennas are proposed for wireless broadband communication systems in the mm-wave range. Two lens antenna configurations for base station applications are presented and evaluated in terms of radiation characteristics, feeding system, input reflection loss, bandwidth and fabrication tolerances. The system requirements to provide optimum power distribution over the cell and good control of the cell boundaries are achieved. These lens antennas are designed for circular symmetric cell coverage and use a circular waveguide as the feed targeting typical applications at 60 GHz and 40 GHz range. The same concept is applicable for non- symmetrical cells with other feeds. Simulations are performed using Geometrical and Physical Optics codes as well as Finite Elements codes. Theoretical results are verified by measurements, showing good agreement.     

超宽带（UWB）短脉冲天线性能改善方法研究

分析了各种超宽带短脉冲天线的性能 ,针对各天线存在的不同特点采取不同的措施进行改进。改变对数周期天线的馈电方式可以避免滞后失真 ;根据 WU- KING偶极子理论 ,对圆柱单极子天线、单圆锥天线和 TEM喇叭天线等进行加载可以有效减小反射 ,改善了天线辐射短脉冲的性能 ,但同时也导致了辐射效率的降低     

Design Considerations and Performance of Circularly Polarized Tv Antennas

This paper discusses those concepts and objectives which are important to the broadcaster considering circular polarization. The results of polls taken among viewers as to the quality of CP reception are presented. Achievements in design, development and fabrication of CP hardware are also described.     

Antennas and Propagation Measurement Techniques for UWB Radio

The progressive development of Ultra Wide Band (UWB) antennas and microelectronics allows for a wide range of future UWB radio communication applications. The paper focuses on testing and measuring various antennas and propagation aspects important in UWB radio. The ‘Delft approach’ of measuring UWB antennas using time-domain measurement techniques is explained including the diagnostics of antenna mismatch and wave scattering from the inside and the antennas environment. The approach is illustrated with measurements.The experimental time-domain set up allows instantaneous measurements up to 26GHz. After an overview of various UWB antennas some latest developments of a miniaturized antenna are reported. UWB channel measurements in ‘short-range radio’ illustrates that good insight in the propagation of short radar pulses can be obtained. Leo P. Ligthart was born in Rotterdam, the Netherlands, on September 15, 1946. He received an Engineer's degree (cum laude) and a Doctor of Technology degree from Delft University of Technology in 1969 and 1985, respectively. He is fellow of IEE and IEEE. He received Doctorates (honoris causa) at Moscow State Technical University of Civil Aviation in 1999 and Tomsk State University of Control Systems and Radioelectronics in 2001. He is academician of the Russian Academy of Transport. Since 1992, he has held the chair of Microwave Transmission, Radar and Remote Sensing in the Department of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology. In 1994, he founded the International Research Center for Telecommunications and Radar (IRCTR) and is the director of IRCTR. Prof. Ligthart's principal areas of specialization include antennas and propagation, radar and remote sensing, but he has also been active in satellite, mobile and radio communications. He has published over 300 papers.     

A Circuit-Theoretic Approach to the Design of Quadruple-Mode Broadband Microstrip Patch Antennas

A novel method for the design of broadband patch antennas is described. The approach taken is to broadside couple two dual-mode patch antennas, resulting in a quad resonance antenna. The equivalent circuit of the antenna is similar to that of microwave filters, thus filter design techniques maybe employed to synthesize the antenna to obtain maximum return-loss bandwidth. This is the first time an increase in the bandwidth is achieved on a relatively thin substrate antenna as a result of coupling four resonant modes using two stacked circular microstrip patches. Electromagnetic simulation and measured results demonstrate bandwidth improvement of over four times that of a single-mode design.     

Coplanar Waveguide Fed Printed Antenna with Compact Size for Broadband Wireless Applications

A novel and simple coplanar waveguide fed compact antenna is introduced in this paper. The antenna structure combines the advantages of CPW with those of the broadband antenna and simplifies the structure of the antenna by reducing the number of metallization level to construct uni-planar antenna. Prototype of the proposed antenna have been constructed and studied experimentally. The measured results agrees well with the simulated prediction and shows a broad bandwidth of 6 GHz ranging from 3.5 GHz to 9.5 GHz with VSWR ≤2 (return loss ≤−10 dB), which is equivalent to 92.3% impedance bandwidth centered at 6.5 GHz. The proposed antenna shows stable radiation characteristics, gain and axial ratio of less than 1 dB over the whole operating bandwidth. Furthermore, an extensive parametric study was performed to realize the relationship between the resonance frequencies of the broadband antennas and different parameters which is helpful for advancement of the antenna design.     

应用于毫米波段的宽带波束调控超表面设计

毫米波段因其较高的数据传输速率和较大的容量而备受关注。为满足现代通信系统对宽带、波束偏转和高辐射效率等天线需求,本文提出了一种工作在88.5～94.6 GHz频带范围内的石墨烯-金属复合结构超表面。该超表面通过调节石墨烯的费米能级,对超表面单元的反射相位进行实时调控编码。调整金属层结构尺寸,可以调制不同编码状态下超表面单元的相位、幅度响应以及编码频段范围。经优化设计,在石墨烯费米能级分别为0 eV和1 eV时,编码超表面单元在88.5～94.6 GHz的宽频带内具有180°±20°的反射相位差,并且反射幅度均大于0.7。利用该单元设计了7×7的超表面,通过合理排布编码单元,可对毫米波段波束进行偏转和多波束切换等动态调控。实验结果显示,单波束最大偏转角度可达105°(-55°～50°),且可实现1～5个波束的切换。该超表面为多功能天线设计提供了新的解决方案,在高速无线局域网、车载雷达、卫星通信等领域具有潜在的应用价值,对毫米波段通信技术的发展具有重要意义。     

最小失配的宽带天线匹配网络设计

本文从控制网络输入端口反射系数出发,提出了一种最小失配的宽带天线匹配网络的设计方法。利用精英保留非劣排序遗传算法分别设计了最小失配的天线无耗匹配网络和有耗匹配网络,实现网络输入端口反射系数和传输功率增益的多目标优化,并对匹配网络的传输函数对负载变化的灵敏度进行了分析。仿真实验表明,所设计的最小失配的匹配网络具有随负载变化灵敏度小的优点,证明了该方法的有效性。     

适用于移动通信的宽频带微带天线

该文研究新型的宽频带微带天线,采用一种具有双层贴片结构的微带天线的形式,并用在探针顶端加电容性金属圆片来抵消探针感性的方法,增加了天线的工作带宽。制作适用于第二代和第三代移动通信的宽频带微带天线,测试结果显示天线具有良好的带宽特性,能够满足移动通信系统对天线的带宽要求。     

Design of Modified Short Backfire Antennas for Millimeter-Waves Wireless LAN Applications

A set of novel modified short backfire antennas are proposed and designed for the application of millimeter-wave wireless LAN systems, by using the FDTD method. By changing the geometrical parameters and feeding structure, the short backfire antennas can generate different kinds of radiation patterns, including narrow pattern, fan-like pattern and conical patterns. Antenna parameters such as reflection bandwidth, input impedance, and far field radiation pattern are presented for each kind of antennas. The proposed different kinds of antennas are suitable for various purposes of wireless LAN applications.     

宽带双频双极化星载赋形反射面天线优化设计

为拓宽星载赋形反射面天线的工作带宽,运用物理光学(PO)、物理绕射理论(PTD)和极小极大值算法(Minimax)对其进行了设计.首先利用PO与PTD相结合的方法来计算天线远场,然后应用Minimax算法对目标函数进行优化来实现宽频带内的波束赋形.优化过程中同时考虑了天线的增益和带宽,并采用归一化的电场来进行构建目标函...     

Application of Characteristic Modes and Non-Foster Multiport Loading to the Design of Broadband Antennas

A conceptual framework is proposed to systematically design antennas with broadband impedance and pattern characteristics using multiple reactive loads. Antennas of arbitrary geometry can have their bandwidths expanded using this technique. The technique is applied to a narrow band thin wire dipole antenna to demonstrate its main features. It is shown that the loaded antenna resonates a desired current over a wide frequency band. The loads are shown to require non-Foster elements when realized. Simulations demonstrate the broadband characteristics of both the dipole input impedance and radiation pattern.