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1.
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
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五种猛禽的食性食量分析 总被引：1，自引：0，他引：1
五种猛禽——领角、燕隼、省鹰、松雀鹰和草均具有捕食农田害鼠的习性，但各自对不同种类的鼠类的嗜食程度不同。领角喜食小家鼠和板齿鼠，不喜食褐家鼠；燕隼喜食板齿鼠、黄毛鼠和褐家鼠．不喜食小家鼠；雀鹰对褐家鼠的嗜食性对比于平均食量的差异并不显著；松雀鹰极喜食小家鼠和板齿鼠，不食褐家鼠． 相似文献
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应用FDTD方法分析TEM喇叭天线阵列的瞬态辐射特性，分析了阵列单元之间的互耦对天线阵列远场辐射的影响。TEM喇叭天线阵列单元沿E面叠状排列可以改善阵列的低频辐射。原理上阵元越多，天线阵列的增益越高。而线性阵列只压缩一个面的方向图。改变阵列单元间馈入信号的时延，可以实现阵列方向图主辩方向的偏移。用半TEM喇叭天线组成槽状排列二元线阵和四元线阵，进行了相应的原理性实验，实验结果与理论数值模拟基本一致。 相似文献
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潘营利 《渭南师范学院学报》2004,19(5):21-23
给出了含有完全耦合的互感耦合元件电路和含有次级短路的互感耦合元件电路动态过程的处理方法，并对处理结果及含有互感耦合元件电路动态过程的一般特征作了说明，指出互感耦合元件不同于电感元件．一般情况下，由互感耦合元件和电阻组成的电路是二阶电路，而由互感耦合元件及电阻、电容组成的电路是三阶电路． 相似文献
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在圆柱形介质谐振器天线单元分析的基础上,设计了一种4单元介质谐振器天线阵列。天线阵采用微带线馈电网络,保证单元之间满足相位匹配关系,使该天线阵列具有良好的定向辐射特性,而且在带宽方面满足要求。 相似文献
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设计了一种多分支平面印刷天线,采用微带线馈电方式,其中微带线设计成T形,与辐射单元匹配.辐射单元由3个L形的金属面结构构成,其分别工作在2.4 GHz、3.5 GHz和5.4 GHz,可应用于无线局域网（WLAN）和全球微波互联接（WiMAX）系统.通过电磁仿真软件HFSS对这种天线进行设计,在WLAN应用频段上10 dB阻抗带宽分别为1 GHz （4.9～5.9 GHz）和310 MHz （2.24～2.55 GHz）;在WiMAX应用频段上10 dB阻抗带宽380 MHz （3.3～3.68 GHz）.实测结果表明,这种天线具有良好的远场辐射特性,其增益在2.5～4.7 dBi之间. 相似文献
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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
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《校园英语(教研版)》2016,(5)
Square-shaped Split-ring resonator(SRR) lefthand Material(LHM) is proposed in Radio frequency band and S parameter extraction method was used to extract the effective permittivity and permittivity are all negative, hence verifying the nature of its left-hand properties. LHM is put on to dielectric layer of the center frequency of 920 MHZ microstrip patch antenna with 50 Ω coaxial feed. Then the left-hand microstrip patch antenna and conventional antenna are compared, finding that return loss S11 down from- 30 dB to-60 dB. 相似文献
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翻译是实现跨文化交流、增进不同文化背景的人们互相理解的重要途径。随着我国改革开放的深入和对外交流的加强,翻译已经融入我们生活的每一个角落,做好翻译工作至关重要。现从中英思维差异的角度探讨怎样做好翻译工作。 相似文献
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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... 相似文献
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设计艺术教育,须注重“道器关联”的作用。“道”与“器”是相互转化、互为依存的辩证关系,如同“鸟之两翼,车之两轮”。须相互补充、转换、同步发展,偏执一隅会影响设计艺术教育的发展和提高。 相似文献
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耦合振荡系统的等效阻抗为定量、定性分析高频耦合回路提供了方便，本文以互感耦合电路为例，对其进行了推导并说明了各量的物理含义，给出了耦合回路的等效电路和等效电路的总阻抗表示式。 相似文献
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无论是韦伯最早用来直接探测引力波的铝柱,还是当今探测引力波的主流设备激光干涉仪,都是静止固定的天线.对来自外界的各种波不加选择地一概接收,造成波之间互相干扰;再加上来自地表的噪音,使被测信息难以辨识.利用磁悬浮陀螺作为探测引力波的天线,在旋转的陀螺减速过程中,可能与某一频率相近的引力波共振,使信息得到放大;有效地提高灵敏度并避免地面杂散信号的干扰. 相似文献
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范月娇 《华侨大学学报(哲学社会科学版)》2014,(4):86-96
区域物流服务能力与区域经济发展水平之间存在相互影响、相互依赖、相互促进的耦合关系,为了量化这种关系,首先分别建立了区域物流服务能力和经济发展水平的综合测度指标体系,并选择海西20个城市2004年、2008年和2012年的数据,利用因子分析法测度其综合值;然后,基于该综合值并利用耦合度模型计算了这三个年份海西各城市物流服务能力和经济发展水平耦合度;最后从时间维度和空间维度对其耦合度的差异进行了分析。研究结果表明,海西区域物流服务能力和经济发展水平耦合度在时间上总体趋势表现为逐步提高的态势;在空间上存在内部差异,而且不同年份其差异特征明显。 相似文献
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ZHONGShun－shi CUIJun－hai 《上海大学学报(英文版)》2001,5(4):295-298
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. 相似文献
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中小学组织结构创新,在其内部各组成要素结合方式的优化上,必须更多地考虑集成创新的思路。将松散耦合与紧密耦合加以连接,集成一种新的耦合系统,有利于资源要素的优势互补,在一定程度上推动学校的进一步发展。 相似文献
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经济发展不仅是校园文化发展的基本动力,也是其决定性因素。社会经济和校园文化在发展过程中相互作用,相互影响。校园文化也以其特有的性质与功能,反作用于社会经济。实现二者的有机结合,对于它们自身的发展至关重要。 相似文献
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