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1.
INTRODUCTIONInvestigationofphotonicbandgap(PBG)materialsiscurrentlyoneofthemostactivefron-tiersinengineeringandphysics.PBGmaterialshaverecentlyemergedasanewmultidisciplinaryfieldofstudy(Kesleretal.,1996;Yablonovitch,1994;SimovskiandHe,2001).APBGstructurecanhaveabandgapwithinwhichelectromagnetic(EM)wavepropagationispreventedinalldirec-tions(Joannopoulosetal.,1997;Ozbayetal.,1994).Foratwo-dimensionalPBGmaterial,thepropagationofanEMwavewithinitsbandgapispreventedinalldirectionswithin… 相似文献
2.
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) 相似文献
3.
A new patch antenna with metamaterial cover 总被引：6，自引：0，他引：6
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… 相似文献
4.
Novel circularly-polarized ceramic dielectric resonator antenna excited by a corner-cut square patch
A ceramic dielectric resonator antenna excited by a corner-cut square patch for the circularly-polarized operation is introduced.
The effect of patch size and cut size is investigated, showing that the resonant frequency of the antenna can be changed by
simply changing the patch size. The reflection, axial ratio, and radiation characteristics of the antenna are found. Measurements
were carried out to verify the design. The antenna is compact in structure, which is attractive in the application as the
satellite communication terminals. 相似文献
5.
在综合分析了微带平面天线阵列馈电网络的两种传统馈电方式的基础上,提出了一种在微波工程应用中实际使用的一种新型馈电网络,提高学生理论知识与实践相结合的能力,更好的掌握最新技术发展。其新型馈电网络由一种左-右手混合微带传输线构成,可以获得高于传统并联馈电网络的天线阵列增益;同时,可以修正传统串联馈电网络的天线阵列辐射方向图的波束偏移,给出了一个工作频率为35GHz的2×2微带面阵的馈电网络设计案例,验证了其理论的正确性。 相似文献
6.
为提高圆形微带贴片天线的性能,提出将一种新型圆柱电磁带隙(EBG)结构应用于天线中,这种柱形EBG基片由两种不同周期单元组成,分别是金属环和接地过孔,形成一种辐射状的圆形周期结构.首先设计了一个圆形微带贴片天线,然后应用电磁仿真软件HFSS对两种周期结构的参数进行了优化分析,最后对加载EBG结构前后微带贴片天线的辐射方向图和回波损耗进行了比较.结果表明,在阻抗匹配良好的前提下,天线增益增强了4.6dB左右,提高了天线的应用性. 相似文献
7.
为了适应卫星通信系统终端的需求,设计了一种三频段天线,辐射贴片的基本形状为四周圆角的矩形,在贴片上分别开T形槽和L形槽,使天线产生3个工作频点。通过对辐射贴片的电流分布和槽形结构进行分析,发现开槽可使电流路径增加,在所需的频段范围内能有效降低回波损耗;同时发现,减小天线的接地面宽度,可减小天线尺寸,从而提高天线的辐射效率。实测结果表明该天线能满足设计要求。 相似文献
8.
文章通过时域有限差分(Finite-Difference Time-Domain,FDTD)方法分析3维(three dimensional)微带天线的散射参数和远场主极化方向图和交叉极化方向图,仿真结果(simulation results)与文献及ansoft软件的仿真结果进行了对比,证实了采用2阶Mur吸收边界条件的FDTD算法的有效性. 相似文献
9.
为了实现双频天线的小型化,对平面倒F形天线给出一种改进,在辐射贴片上开一个T形槽．再将它的尾部向内折叠。通过与L形开槽的倒F形天线相比表明：改进后天线的结构更加紧凑,尺寸减小30％以上,且在给定的工作频段具有良好的辐射特性。 相似文献
10.
MEHTA Amit 《浙江大学学报(A卷英文版)》2007,8(12):1901-1904
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. 相似文献
11.
温煜东 《晋城职业技术学院学报》2013,(6):59-61
本文设计了一种应用于无线局域网的电磁带隙结构(EBG)的微带天线。通过在微带贴片天线的辐射单元周围加载蘑菇型EBG结构,使得天线的带宽、增益性能得到了显著改善。仿真结果表明,与普通贴片天线相比,加载EBG结构时天线带宽增加了6%,主辐射方向上增益增大了1.98dB。 相似文献
12.
用于通信的超宽带印刷天线 总被引：1，自引：1，他引：1
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… 相似文献
13.
A low-sidelobe circularly-polarized （CP） microstrip patch array for 2.4 GHz radio frequency identification （RFID） readers is presented. The antenna array with a Chebyshev current distribution is composed of 6 microstrip elements. The CP operation is obtained by the quasi-square patch with difference in lengths of the two sides. The antenna has been investigated numerically and experimentally. Measured results show that the array has a Chebyshev pattern with the sidelobe level of -23 dB, the half-power beamwidth of 16° and an impedance bandwidth （S11 ≥-10 dB） of 130 MHz, which is suitable for RFID reader applications. 相似文献
14.
一种平面倒F型三频手机天线设计 总被引：1，自引：0，他引：1
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. 相似文献
15.
Mohammed Ahmed ZHONG Shun shi 《上海大学学报(英文版)》1999,3(4):279-281
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｔｈｅｓｕｃｃｅｓｓｆｕｌｃｏｍｍｅｒｉｃａｌａｐｐｌｉｃａｔｉｏｎｓｏｆｗｉｒｅｌｅｓｓｔｅｃｈｎｏｌｏｇｙｄｅｍａｎｄａｐｐｒｏｐｒｉａｔｅａｎｔｅｎｎａｓ．Ｔｙｐｉｃａｌｌｙ,ａｄｕａｌｐｏｌａｒｉｚａｔｉｏｎｏｐｅｒａｔｉｏｎｓｕｃｈａｓｓｉｍｕｌｔａｎｅｏｕｓｖｅｒｔｉａｌａｎｄｈｏｒｉｚｏｎｔａｌｐｏｌａｒｉｚａｔｉｏｎａｎｔｅｎｎａｗｉｔｈｌｏｗｐｒｏｆｉｌｅ,ｓｍａｌｌｓｉｚｅ,ａｎｄｌｉｇｈｔｗｅｉｇｈｔｉｓｒｅｑｕｉｒｅｄｆｏｒｗｉｄｅｓｐｒｅ… 相似文献
16.
HUANG Biao YAN Guo-zheng LI Qian-ru 《浙江大学学报(A卷英文版)》2007,8(10):1560-1567
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. 相似文献
17.
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. 相似文献
18.
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． 相似文献
19.
A bidirectional deployable parabolic cylindrical reflector for an L-band synthetic aperture radar is presented in this study, in which a self-deployed antenna with low weight was designed. The antenna consists of four curved surfaces formed from thin sheets of composite materials connected by hinges along the edges, and the reflective surface is provided by the front surface. The edge profiles of connecting lines were obtained through geometric analysis. A scaled model, including design and manufac- ture, was demonstrated to validate the process from the folded state to the fully deployed state. The non-contact synchronous vision measuring method was used to test the basic frequency of the scaled model, and the test results gave the verification of the analyses. Compared with the existing unidirectional deployable antenna, this new type of bidirectional deployable antenna can be applied to larger-size antennas and has better performance because the glass-woven tape connections were substituted with more reliable hinges. Static, modal, harmonic response, and transient response analyses of the full-sized reflector structure were mod- eled with the commercial finite element （FE） package ABAQUS. The modeling techniques were developed to predict the struc- tural dynamic behavior of the reflector and the results showed that the first natural frequency was 0.865 Hz, and the reflector structure had good stiffness in three directions. This proposed structure has very high stiffness-to-mass ratio because of its hollow solid construction. A preliminary simulation of radiation properties of the parabolic cylindrical antenna, fed by an off-set linear feed horn array, was conducted to obtain the radiation pattern of the feed and the reflector. 相似文献
20.
基于Matlab的对称振子天线分析 总被引：2，自引：0，他引：2
曾永西 《泉州师范学院学报》2009,27(2):30-33
对称振子天线是应用最广泛的线天线,分析与设计对称振子天线的难点之一是其复杂的数值计算与方向图的可视化输出．文章利用Matlab工具来分析对称振子天线辐射的方向图及方向系数、辐射电阻、输入阻抗等重要参数,结果表明,Matlab工具能够有效应用于对称振子天线分析设计． 相似文献