用于通信的超宽带印刷天线

1IntroductionUltra-wideband(UWB)microwave antennas are ofinterest for a variety of applications such as electroniccountermeasure,transient radars,mine detection,andunexploded ordnance(UXO)location and identifica-tion.In the early2002,the release of the UWB forcommercial communications by the Federal Communi-cation Commission(FCC,USA)sparked renewed in-terest in the subject of UWB antennas.Conventional UWB antennas such as log-periodic orspiral antennas exhibit good UWB characteristi…     

使用共面波导馈电的超宽带双侧渐变槽线天线

为了拓展渐变槽线天线的工作频带,提出一种采用共面波导新型馈电结构的双面印刷对跖型渐变槽线天线.基于对渐变槽线天线之宽频带特性受限于现有馈电方式的分析,改用蚀刻于背板的共面波导至双面印刷对跖渐变槽线的行波式转接.其仿真和实验结果一致表明:该馈电方式使天线的阻抗具有高通频响特性,且保持较好的辐射方向性图,在3 GHz以上的...     

应急通信跨段中继套筒单极子天线设计

将套筒单极子天线用于应急通信的V/U频段,提出了一个无地板的套筒天线设计,用An-soft HFSS软件研究该天线的多频带特性和辐射特性,并从工程角度优化了该天线的参数,套筒和同轴电缆均为标准尺寸,便于批量生产。仿真结果表明其在V/U双段能够满足所需的驻波比带宽,并且具有很好的辐射特性。VSWR小于2的频率范围是V段：127MHz-149MHz,带宽22MHz;U段：417 MHz-450MHz,带宽33MHz。取消地板以后,该天线横向尺寸大为减小,便于车载和移动使用。     

New band-notched UWB antenna

A simple and compact ultra wideband (UWB) printed monopole antenna with band-notched performance is proposed in this paper. The antenna is partially grounded so that the Q value is depressed and the impedance bandwidth is broadened. A small strip bar is loaded on each arm of the similar U-shaped radiator. The impedance bandwidth of the antenna overlap with IEEE 802.11a is rejected consequently. The geometry parameters of the antenna are investigated and optimized with HFSS. The measured bandwidth of the proposed antenna occupies about 7.89 GHz covering from 3.05 GHz to 10.94 GHz with expected notched band from 4.96 GHz to 5.98 GHz. A quasi-omnidirectional and quasi-symmetrical radiation pattern in the whole band is also obtained. As a result, a UWB wireless communication system can be simplified with the band-notched UWB antenna presented.     

WUSB中新型带陷UWB天线

给出了一种紧凑的可用于WUSB的新型带陷超宽带印刷单极子天线．天线由内嵌条带的U形环组成并采用部分接地技术,从而使天线具有带陷超宽带特性．实测结果表明该天线输入端驻波比小于2的绝对阻抗带宽为7．88GHz,覆盖了3．12～11GHz的频率范围,其中5．06～5．89GHz范围内具有带阻特性．讨论了各几何参数对天线性能的影响,同时获得了该天线相对稳定的、近似全向且对称的测试方向图．由于此种天线无需额外的带阻滤波器来隔离天线与其他通信系统的干扰,从而大大简化了WUSB系统的设计．     

一种快速、准确的分析多导体共面波导传输线的方法

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　ＴｈｅｓｐａｔｉａｌＧｒｅｅｎ’ｓｆｕｎｃｔｉｏｎｓｏｆｍｕｌｔｉ ｌａｙｅｒｅｄｍｅｄｉａａｒｅｕｓｅｆｕｌｉｎａｎａｌｙｓｉｓｏｆａｎｔｅｎｎａａｎｄｉｎｔｅｇｒａｔｅｄｃｉｒｃｕｉｔｓｔｒｕｃｔｕｒｅｓ.Ｔｈｅｙａｒｅｃｏｎｓｔｒｕｃｔｅｄｉｎｔｗｏｓｔｅｐｓ.ＴｈｅｆｉｒｓｔｉｓｔｏｄｅｒｉｖｅｔｈｅｓｐｅｃｔｒａｌＧｒｅｅｎ’ｓｆｕｎｃｔｉｏｎ .ＴｈｅｓｅｃｏｎｄｉｓｔｏｍａｋｅｉｎｖｅｒｓｅＦｏｕｒｉｅｒｔｒａｎｓｆｏｒｍｏｆｔｈｅＧｒｅｅｎ’ｓｆｕｎｃ ｔ…     

宽带印刷天线与双极化微带及波导缝隙天线阵

In order to meet the urgent needs in wireless communications, microwave image synthetic aperture radars （SAR）, and electronic warfare systems, this dissertation studies several types of broadband dual-polarized planar antenna elements and arrays, and proposes a few of novel designs with experimental verification. The main accomplishments reported in the dissertation are as follows.     

宽带印刷天线与双极化微带及波导缝隙天线阵(英文)

In order to meet the urgent needs in wireless com-munications , microwave i mage synthetic aperture ra-dars (SAR) ,and electronic warfare systems ,this dis-sertation studies several types of broadband dual-polar-ized planar antenna elements and arrays ,and proposesa few of novel designs with experi mental verification.The main accomplishments reported in the dissertationare as follows . First ,the phenomena of symmetryin electromagne-tism, both in theory and in applications , are sum-marized.…     

Practical realization of dual S arm antenna for beam steering applications

A dual S shaped micro strip antenna with a realistic feed is proposed for generation of tilted beam radiation pattern pertaining for beam steering applications. To achieve this, four feeding points are located at a distance of 5.6 mm from the antenna centre. These feeding points when excited one by one generate four tilted beams in four different space quadrants, thus yielding a beam steerable antenna. Importantly, since the proposed antenna is symmetrical in the structure, all the four tilted beams have the same radiation pattern characteristics. A further enhancement of the antenna bandwidth is also achieved using 100-μm capacitive coupling between the feed and the antenna strip.     

一种平面倒F型三频手机天线设计

为了实现手机内置天线的小型化和多频段,提出了一种平面倒置F型三频段天线.结构采用空间折叠实现了小型化,开双L型槽实现了多频段工作.测试结果表明,其尺寸和频率都能满足现代无线通信系统对移动终端的要求.     

MI-NLMS adaptive beamforming algorithm for smart antenna system applications

INTRODUCTION The demand for mobile communication services is increasing at a rapid pace throughout the globe. The increasing demand for mobile communication ser- vices in a limited RF spectrum motivates the need for better techniques to improve spectrum utilization. Smart antenna system was adopted by ITU for the IMT-2000 or the Third Generation (3G) wireless networks due to its capability to improve channel capacity and interference suppression. A smart an- tenna system combines mult…     

A four spiral slots microstrip patch antenna for radiotelemetry capsules based on FDTD

Antenna is very crucial to radiotelemetry capsules which can measure the physiological parameters of the gastroin- testinal (GI) tract. The objective of this paper is to design a novel spiral slots microstrip patch antenna for the radiotelemetry capsules communicating with external recorder at 915 MHz located in ISM (Industry, Science, and Medical) bands. The microstrip patch antenna is designed and evaluated using the finite-difference time-domain (FDTD) method. Return loss characteristics and the effect of the human body on resonant frequency are analyzed, and the performances of radiation patterns at different positions of the human alimentary tract are also estimated. Finally, specific absorption rate (SAR) computations are performed, and the peak 1-g and 10-g SAR values are calculated. According to the peak SAR values, the maximum delivered power for the designed antenna was found so that the SAR values of the antenna satisfy the ANSI (American National Standards Institute) limitations.     

A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate

INTRODUCTIONInvestigationofphotonicbandgap(PBG)materialsiscurrentlyoneofthemostactivefron-tiersinengineeringandphysics.PBGmaterialshaverecentlyemergedasanewmultidisciplinaryfieldofstudy(Kesleretal.,1996;Yablonovitch,1994;SimovskiandHe,2001).APBGstructurecanhaveabandgapwithinwhichelectromagnetic(EM)wavepropagationispreventedinalldirec-tions(Joannopoulosetal.,1997;Ozbayetal.,1994).Foratwo-dimensionalPBGmaterial,thepropagationofanEMwavewithinitsbandgapispreventedinalldirectionswithin…     

A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate

A new photonic bandgap (PBG) cover for a patch antenna with a photonic bandgap substrate is introduced. The plane wave expansion method and the FDTD method were used to calculate such an antenna system. Numerical results for the input return loss, radiation pattern, surface wave, and the directivity of the antennas are presented. A comparison between the conventional patch antenna and the new PBG antenna is given. It is shown that the new PBG cover is very efficient for improving the radiation directivity. The physical reasons for the improvement are also given. Project supported by the National Natural Science Foundation of China (No. 90101024) and the Science and Technologies of Zhejiang Provinc (No. ZD0002)     

利用FDTD方法全波分析与设计管道中用于整流天线的微带天线

1 Introduction In some nuclear power plants , chemical plants ,power plants ,the pipe cracks detection is very diffi-cult because of its thinness and fatalness . So the in-pipe inspection micromachine is developed . The rec-tenna (rectifying antenna) ,rec…     

A New Dual Polarized Aperture—Coupled Printed Array for SAR Applications

This paper presents a new design of dual polarized aperture-coupled printed antenna array,The finite-difference time-do-main(FDTD) analysis of an aperture-coupled microstrip element is performed,and the effects of antenna parameters on ist characteristics are obtained to guide the design of the printed array,Then an 8^2 dual polarized array design in X-band is introduced with configuration plots,In order to improve its isolation and cross polarization.an outphase-displacement feeding technique is adopted in the feed network.Also,the round bends are used instead of conventional right-angle bends so as to acieve better VSWR performance,Experimental results are presented.indicating the validity of the design.This dual polarized array can be applied as a sub-array of paceborne SAR systems.     

基于多用户OFDM和分布式天线的认知无线电中最优子载波分配方案

分别在平坦衰落和频率选择性衰落的无线信道模型中建立了基于多用户正交频分复用技术（OFDM）和分布式天线的认知无线电系统中子载波分配模型.该模型不再用＂干扰温度＂限制认知用户来保护主用户,而是规定主用户在其所有子载波上的吞吐量之和需要高于一定的门限.然后,根据不同信道模型的特点提出了最优子载波分配方案,该方案利用分支定界法和隐枚举法最大化系统的吞吐量.最后,利用Pegging算法提出了效率与公平折中的子载波分配方案.仿真证明,在不同场景中所提出的子载波分配方案与现有方案相比在吞吐量和公平性方面均具有较大的优势.     

差信道环境下简单有效的图像传输方法

The constrained Viterbi algorithm (C-VA) makes use of some prior reliable information to reduce complexity andimprove performance of Viterbi algorithm (VA). However it can only be used in the concatenate code scheme because thedetection result of cyclic redundancy check code (CRC) is exploited to provide reliable information. In this paper, a differentway is proposed to provide reliable information for C-VA, which is possible to be used in simple codec. Known bits were addedto the set partitioning in hierarchical trees (SPIHT) coded image sequence periodically and directly. They were thought to bereliable information for C-VA in the decoder. Experimental results show that the proposed scheme can obtain much bettererror resilient ability compared with conventional VA under the extremely inferior channel condition if the best desired qualityof reconstructed images can be sacrificed.     

A new patch antenna with metamaterial cover

INTRODUCTION Investigation of metamaterials is currently one of the most active frontiers in engineering and physics. Metamaterials are also called backward-wave mate- rials, double-negative materials, or left-handed mate- rials. Left-handed materials were proposed by Vese- lago (1968). The applications of metamaterials are widely spread in many fields (Pendry, 2000; Grbic and Eleftheriades, 2003; Foteinopoulou et al., 2003), such as imaging apparatus, planar light wave circuits, optica…     

多项式数列和的简捷方法

给出了求关于自然数k的m次多项式数列f(k)=α0k^m α1k^m-1 … αm-1k αm=∑i=0^m αik^m-i的前n项和∑k=1 m f(k)的简单递推公式，而无需应用Bernoulli数，推广了文[1]、[2]、[3]的结论。