A Magneto-Electric Dipole With a Modified Ground Plane

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一种宽带高增益磁电偶极子天线设计

一种宽带高增益磁电偶极子天线设计汪善栋;李民权;潘旭;周永光;沈纯纯;李玄玄【摘要】提出了一种由一对平面偶极子和一对垂直折叠短路贴片组成的新型磁电偶极子天线.通过加载矩形盒反射板,有效减少了副瓣,提高了辐射方向图的一致性,实现了天线的高增益定向辐射.采用有限元法进行分析与研究,结果表明:天线在1 650～2 800 MHz频段内,电压驻波比小于1.5的相对带宽达到52.3％,最大增益10.38 dBi;E面和H面辐射方向图具有低交叉极化、低后瓣特性.该天线具有稳定的增益及良好性能,可应用于移动通信中的基站.%A new Magneto-Electric dipole antenna composed of a pair of horizontal planar dipole and a pair of vertically-oriented folded short patch antenna is proposed.By loading the rectangular box-shaped reflector,the back radiation is effectively reduced,the consistency of the radiation pattern improved,and the high-gain directional radiation of the antenna also realized.Analysis and study with finite element method indicate that the relative impedance bandwidth of 52.3％ for frequency band from 1.65 to 2.80 GHz,and the maximum gain of 10.38 dBi.And the stable radiation pattern in the E-plane and H-plane with low-cross polarization and low back radiation could be achieved.The antenna has stable gain and good performance,and could be applied to the base-station in mobile communication.【期刊名称】《通信技术》【年(卷),期】2017(050)002【总页数】4页(P377-380)【关键词】磁电偶板子;低交叉极化;宽带;高增益【作者】汪善栋;李民权;潘旭;周永光;沈纯纯;李玄玄【作者单位】安徽大学电子信息工程学院,安徽合肥230039;安徽大学电子信息工程学院,安徽合肥230039;安徽大学电子信息工程学院,安徽合肥230039;安徽大学电子信息工程学院,安徽合肥230039;安徽大学电子信息工程学院,安徽合肥230039;安徽大学电子信息工程学院,安徽合肥230039【正文语种】中文【中图分类】TN82随着现代无线通信技术的快速发展，3G、LTE、WiFi和WiMAX等对宽带单向性天线提出了更高的要求。

A METHOD FOR ELECTROPLATING WITH A REFRACTORY MET

专利名称：A METHOD FOR ELECTROPLATING WITH A REFRACTORY METAL发明人：POLIAKOV, Evgueni Georgievich,MASLOV, Valeri, Petrovich,POLIAKOVA, Larissa,Petrovna,KOVALEVSKI, Vladimir, Pavlovich申请号：IB1997001046申请日：19970902公开号：WO98/046809P1公开日：19981022专利内容由知识产权出版社提供摘要：The invention relates to electroplating with refractory metal, mainly tantalum and niobium, from molten salts and can be applied in chemical, metallurgical, pharmaceutical, medicinal industries, turbine manufacture, air- and spacecraft, and other areas of engineering, in creation of corrosion-resistant and barrier coatings. The essence of the invention is that when the article to be coated is immersed into a molten electrolyte containing fluorides of both refractory and alkali metal and a eutectic melt of sodium, potassium and cesium chlorides, the article is warmed up to the working temperature of the electrolyte of 700-770 °C whereupon direct or reverse electric current is passed through the electrolyte, the current parameters being adjusted so that quantity of electricity in the anodic Qa, and cathodic Qc, parts of the electroplating cycle corresponds to the ratio O≤Qa/Qc < 0.9. To improve the article quality it is desirable that the weight of the electrolyte exceeds that of the article by 5 times or more. The technical result attained is the production of uniform-thickness, high quality tantalum or niobium coatings on articles for industrial applications made of conventional materials. Openporosity of the resulting coatings is not higher than 0.001 %, adhesion to the substrate is as high as 8 kg/mm2.申请人：POLIAKOV, Evgueni Georgievich,MASLOV, Valeri, Petrovich,POLIAKOVA, Larissa, Petrovna,KOVALEVSKI, Vladimir, Pavlovich地址：GB,RU,RU,RU,RU国籍：GB,RU,RU,RU,RU更多信息请下载全文后查看。

一种圆极化透镜天线

一种圆极化透镜天线王凯旭;黄衡【摘要】提出了一款宽频带高增益的圆极化毫米波天线.该天线由一个半球形的介质透镜圆顶以及一个圆柱形极化器结合而成,将传统的扩展半球介质透镜与介质极化器融合在一起,既能将线极化波转化成圆极化波(反之亦然),又能有效提高天线的增益.该设计与传统的级联结构(透镜级联极化器)不同,它能够用一个器件同时实现两个器件的功能,并且能大大减小系统的体积,降低插入损耗,减少生产成本.此外,该天线采用3D打印技术来实现,加工精度高并且容易生产,适合于毫米波天线的应用.经过验证,该天线的阻抗带宽能达到38％,轴比带宽为36％,圆极化增益达到22 dBic.【期刊名称】《电波科学学报》【年(卷),期】2018(033)004【总页数】5页(P387-391)【关键词】毫米波天线;宽带天线;圆极化天线;3D打印天线;透镜天线【作者】王凯旭;黄衡【作者单位】香港城市大学电子工程系国家毫米波重点实验室,香港999077;香港城市大学深圳研究院,深圳518057;香港城市大学电子工程系国家毫米波重点实验室,香港999077;香港城市大学深圳研究院,深圳518057【正文语种】中文【中图分类】TN822引言毫米波通信具有很宽的可用带宽(57～64 GHz),能够满足日益增长的高速无线通信的要求, 因此,近年来受到越来越多的关注．在毫米波无线通信系统中,天线扮演着关键的技术．首先,毫米波天线必须具有比较宽的带宽,才能覆盖所需的工作频段．其次,由于毫米波通信过程中有比较高的损耗,因此要求毫米波天线具有比较高的增益,才能实现比较远距离的通信．传统的毫米波高增益天线多采用天线阵列来实现,通过增加天线振子的数量来实现比较高的增益[1-4]．这种方式虽能够有效增加天线的增益,但是需要外加一套馈电网络给每个振子分别馈电．随着天线振子数量的增加,馈电网络也会变得复杂而庞大,更为重要的是,此时馈电网络的插入损耗也会随着增加,这样反而会降低天线的增益．除了天线阵列,在天线的前方增加一个透镜也是提高天线增益的有效方法[5-9]．由于透镜具有体积大的缺点,因此该方法在低频段比较少被采用．但是对于毫米波无线通信,由于工作频率在60 GHz, 工作波长很短,此时透镜的体积就可以大大减少,所以透镜天线在毫米波通信系统中被广泛采用．传统的透镜只能提高天线增益的能力,却不能起到实现圆极化的功能．为了实现圆极化,一般需要采用在底下添加一个圆极化天线源的方式．本文提出了一款新型的毫米波透镜天线,该透镜天线将极化器与传统的扩展半球介质透镜有效融合在一起,通过一个器件,同时实现透镜与极化器的功能,不仅能有效提高天线的增益,还能将线极化入射波转化为圆极化．1 天线结构与设计图1展示了天线的结构图,该天线在传统的扩展半球介质透镜上每隔相同的距离挖出一段长方形的槽.它也可以看成是由顶部的半球透镜以及下边的圆柱形极化器组合而成．该天线的馈源位于透镜的下方,与透镜的距离为g,g的大小会影响天线的增益．此外,为了实现圆极化,馈源部分的线极化方向需要与长方形槽保持45°．整个天线采用3D打印技术加工而成, 3D 打印材料的介电常数是2.9, 损耗角正切是0.01．图1 天线结构图Fig.1 Configuration of the proposed antenna1.1 圆极化的实现图2给出了极化器结构的单元,极化器可以看成由很多个单元组成．从图2可以看到,每个单元由一片介质和一片空气组成,这种结构在x方向和y方向具有不同的介电常数εx和εy,其表达式为:(1)εy=ε0+ε0(εr-1)r．(2)式中,r=w2/(2w1+w2)．图2 极化器的单元结构图Fig.2 Schematic model of polarizer unit图3和图4分别展示了εx和εy的数值计算和仿真结果．其中虚线为数值计算的曲线,实线为软件HFSS的仿真结果．从图中可以看出,仿真结果与数值计算结果很吻合．此外,也可以看出εx 小于εy,即具有x极化方向的电磁波在介质中的传播速度要比y极化方向的电磁波的传播速度快．于是,它们穿过极化器的时候具有不同的相移特性,通过调节极化器的厚度,使得它们的相位差为90°,于是便可产生圆极化特性．图3 有效介电常数εx随不同填充比r 的变化规律Fig.3 Simulation and calculation effective dielectric constants εx versus different ratios r fordifferent εr图4 有效介电常数εy随不同填充比r 的变化规律Fig.4 Simulation and calculation effective dielectric constants εy versus different ratios r for different εr1.2 焦点的位置电磁波穿过传统的扩展半球形介质透镜的光路径如图5(a)所示,电磁波从焦点出发,在透镜表面发生折射,近光轴的电磁波经过折射后传播方向接近平行于z方向,从而提高天线的增益．而对于文中提出的圆极化透镜天线,电磁波穿越透镜时,发生了两次折射作用,第一次折射发生在极化器与半球透镜的交界处;第二次折射发生在透镜球面上．根据折射定律,可以得出sin φe/sin φr=n/ne.(3)式中,n和ne 分别是半球透镜和极化器的有效介电常数．由于极化器中有一部分是空气,故 n>ne,因此φe> φr,h1> h2. 从以上的分析可以看出,当在透镜的扩展部分挖出一些长方形槽时,不仅能实现圆极化特性,还能通过折射作用减小透镜的焦点距离,从而有效地减小透镜的体积、插入损耗,以及加工成本．(a) 传统透镜(a) Traditional lens(b) 圆极化透镜(b) Circular polarizing lens图5 电磁波在透镜中的传播路径图Fig.5 The path of the waves pass through the lens2 天线的加工与测试为了验证我们的分析,我们对该天线进行仿真与测试,通过优化之后,天线的具体参数如下:h=6.5 mm, R=10 mm, g=0.7 mm, w1=0.5 mm, w2=1 mm．然后采用3D 打印机对优化后的天线进行加工,加工之后的天线实物图如图6所示．天线的馈源我们采用WR15的开口波导,通过开口波导产生线极化辐射波．图6 加工之后的圆极化透镜以及天线馈源Fig.6 Prototype of the CP lens and the antenna source在天线回波特性的测试中,我们采用了安捷伦的网络分析仪E8361A进行试验测试;而对于天线远场特性(例如增益,轴比,方向图等)的测试则是采用NSI 2000 系统进行测试,由于试验仪器的限制,测试的频段只从50 GHz 到 67 GHz.图7展示了天线仿真与测试的匹配特性,可以看出仿真的阻抗带宽(小于-10 dB)从51 GHz 到75 GHz,测试的范围从51 GHz 到67 GHz．天线的阻抗带宽主要由馈源天线决定．图8展示了天线的轴比和增益特性,由图8可以看出:天线仿真的圆极化带宽(AR<3 dB)从50 GHz 到72 GHz,实测结果从 50 GHz 到67 GHz;天线的宽带圆极化特性主要是由极化器结构决定的;天线仿真的最大增益可以达到22 dBic,实测的增益可以达到21 dBic,增益的大小主要由半球透镜的半径决定,并且也受馈源位置的影响．图9比较了天线的方向性和增益,方向性比增益平均高了1.2 dB, 通过计算,可以看出天线的效率约为78%．在这个结构中,天线的损耗主要来源于3D 打印材料的损耗,由于我们采用的3D打印材料比较大,所以导致天线的损耗比较大,从而效率比较低．为了提高天线的效率,可以通过采用低损耗的3D打印材料来解决．图10 比较了在50 GHz 和60 GHz(φ=±45°)的方向图,可以看出,仿真和测试的方向图比较接近．而且在其中一个面的旁瓣比较大(约为-12 dB),这是由天线源的表面波导致的,可以通过减小表面波的方式来减小方向图的旁瓣．图7 天线的回波特性Fig.7 Reflection coefficient图8 轴比和增益Fig.8 Axial ratio and gain图9 方向性与增益Fig.9 Directivity and gain(a) 50 GHz(b) 60 GHz图10 电磁波在透镜中的传播路径图Fig.10 The path of the waves passthrough the lens3 结论本文提出了一款新型的圆极化透镜天线,通过在传统的扩展半球介质透镜开槽的方式,能够将传统的透镜改造成具有圆极化功能的透镜天线．与之前的圆极化透镜相比,这种结构能够在实现高增益的同时,达到比较宽的轴比带宽．并且具有比较小的体积,能够减小插入损耗．此外,使用3D打印技术进行加工,能够将该设计应用于毫米波通信频段．由于材料的损耗比较大,该结构的增益很难进一步提高,下一步的工作可以通过采用薄透镜的方式来减小介质损耗,从而有效提高天线的增益．参考文献【相关文献】[1] MIURA Y, HIROKAWA J, ANDO M, et al. Double-layer full-corporate-feed hollow-waveguide slot array antenna in the 60 GHz band[J]. IEEE transactions on antennas and propagation, 2011, 59(8): 2844-2851.[2] LI Y J, LUK K M. Low-cost high-gain and broadband substrate integrated waveguide fed patch antenna array for 60-ghz band[J]. IEEE transactions on antennas and propagation, 2014, 62(11): 5531-5538.[3] WONG H, LUK K M, CHAN C H, et al. Small antennas in wireless communications[J]. Proceeding of IEEE, 2012, 100(7): 2019-2121.[4] LI Y J, LUK K M. A 60-GHz wideband circularly polarized aperture-coupled magneto-electric dipole antenna array[J]. IEEE transactions on antennas and propagations, 2016, 64(4): 1325-1333.[5] MIRBEIK A, TAVASSOLI V, AYAZI F, et al. Three-dimensional, ultra-wideband micromachined millimeter-wave hemispherical shell antenna: theoretical concept and calibration[J]. IET microwaves, antennas & propagation, 2015, 10(5): 525-535.[6] DANCILA D, VALENTA V, BUNEA A C, et al. Differential microstrip patch antenna as feeder of a hyper-hemispherical lens for F-band MIMO radars[C]//Global Symposium on Millimeter Waves (GSMM) & ESA Workshop on Millimetre-Wave Technology and Applications, 2016: 1-4.[7] PARK K Y, WIWATCHARAGOSES N, CHAHAL P. Wafer-level integration of micro-lens for THz focal plane array application[C]//IEEE 63rd Electronic Components and Technology Conference, 2013: 1912-1919.[8] GHEETHAN A A, DEY A, MUMCU G. Passive feed network designs for microfluidic beam-scanning focal plane arrays and their performance evaluation[J]. IEEE transactions on antennas and propagation, 2015, 63(8): 3452-3464.[9] NGUYEN N T, SAULEAU R, PEREZ C J M. Very broad-band extended hemispherical lenses: role of matching layers for bandwidth enlargement[J]. IEEE transactions on antennas and propagation, 2009, 57(7): 1907-1913.。

低RCS宽带磁电偶极子贴片天线设计

低RCS宽带磁电偶极子贴片天线设计张晨;曹祥玉;高军;李思佳;黄河【摘要】该文设计了一种低雷达散射截面(RCS)的宽带磁电偶极子贴片天线，其中印刷在介质板上的金属贴片为电偶极子，3个金属过孔连接辐射贴片与金属地板构成磁偶极子。

整个天线采用“T”型渐变馈电结构同时激励电偶极子与磁偶极子，天线的频带范围为7.81~13.65 GHz，覆盖了整个X波段。

实测和仿真结果表明，通过在磁电偶极子贴片天线底面采用开槽技术并优化开槽的形状、大小、位置等变量，在天线工作频带范围内实现了RCS的减缩，最大缩减量达到了17.9 dB，同时天线保持了增益稳定不变，E面、H面方向图一致的特性。

%A low Radar Cross Section (RCS) and broadband Magneto-Electric (ME) dipole patch antenna from 7.81 GHz to 13.65 GHz covering the whole X band is designed and fabricated. Metal patches printed on the substrate form the electric dipoles, three metallic vias connected to the radiation patches and the metal ground account for the magnetic dipole radiation. The whole antenna is connected with a T-shaped feed structure which excites electric and magnetic dipoles simultaneously. Numericaland experimental results incident that the RCS of the ME dipole patch antenna can be reduced inthe whole bandwidth which the largest value is up to 17.9 dB by cutting slots on the ground and optimizing the size, shape, position of the slots. Also, the antenna shows advanced performances such as stable gain and almost consistent pattern in E and H plane.【期刊名称】《电子与信息学报》【年(卷),期】2016(038)004【总页数】5页(P1012-1016)【关键词】磁电偶极子天线;宽频带;开槽技术;低RCS;一致性【作者】张晨;曹祥玉;高军;李思佳;黄河【作者单位】空军工程大学信息与导航学院西安 710077;空军工程大学信息与导航学院西安 710077;空军工程大学信息与导航学院西安 710077;空军工程大学信息与导航学院西安 710077;西安通信学院西安 710106【正文语种】中文【中图分类】TN821 引言微带贴片天线以其低剖面、易共形等优点在战场通信、监视及其它作战平台上得到了广泛应用，但由于带宽窄，不能用于宽频天线系统，且E面、H面方向图差异较大，不易于组成天线阵[1,2]。

一种新型毫米波磁电偶极子天线阵列设计

一种新型毫米波磁电偶极子天线阵列设计陆贵文;李明鉴【摘要】该文将磁电偶极子天线作为辐射阵子，并应用一种共面波导馈电网络，研究并设计了一种新型4×4毫米波天线阵列。

这种设计不仅具有很宽的阻抗带宽和增益带宽，而且价格低廉易于生产。

仿真和测试结果表明，此天线阵列的相对阻抗带宽为54.5%,3 dB增益带宽为37.1%，在工作频带内(40.2~70.0 GHz)，最大增益为18.1 dBi。

而基于其他技术设计的4×4毫米波天线阵列(如微带天线、偶极子天线)工作频带宽度一般在20%左右，增益一般在16~17 dBi。

所以该文提出的天线阵列设计具有明显的优势。

另外，仿真设计结果和实测的电参数数据有较好的一致性。

%This paper presents a new 4×4 millimeter-wave antenna array, which adopts the magneto-electric dipole as the radiating element and a type of coplanar waveguide feed network to excite the array. This design not only provides very wide impedance and gain bandwidths, but also has features of low cost and ease in fabrication. The simulated and measured results reveal that this array exhibits a wide impedance bandwidth of 54.5% and a wide 3 dB gain bandwidth of 37.1%. Over the operating frequency band (40.2~70.0 GHz), the maximum gain is 18.1 dBi. However, other 4×4 millimeter-wave antenna arrays, designed based on microstrip patch antenna or electric dipole antenna, have the operating bandwidth of about 20% and the gain of 16~17 dBi. Hence, the proposed antenna has an obvious advantage. In addition, the simulated and measured results have a good agreement.【期刊名称】《电子与信息学报》【年(卷),期】2015(000)010【总页数】4页(P2517-2520)【关键词】毫米波天线阵列;磁电偶极子天线;宽带天线【作者】陆贵文;李明鉴【作者单位】香港城市大学毫米波国家重点实验室中国香港;香港城市大学毫米波国家重点实验室中国香港【正文语种】中文【中图分类】TN821为了实现海量数据传输和弥补匮乏的可用频谱，提高载波频率是必然的解决方案。

PAPER

A magnetosphere is formed when a stream of charged particles, interacts with the intrinsic magnetic field of a planet or similar body.A magnetotail is formed by pressure from the solar wind on a planet's magnetosphere.Review：1、the general circumstances surrounding energization inreconnection.2、electron acceleration and fluxe increasing is associated with depolarization front penetrating into the inner magnetosphere.3.fluxes increase at high energies and tend to decrease at lower energies4.electron acceleration in the magnetotail have focused on local acceleration processes atthe reconnection points5. They include betatron acceleration to explain electron acceleration signatures observed in the magnetotail in association with substormstool：In this article, we argue that the use of both kinetic and globalsimulations can answer the question of where and how electrons are accelerated in the magnetotail during substorm-driven dipolarization events.The approach uses Vlasov Maxwell theory together with thecon-struction of particle distribution functions from THEMIS plasma data to locate where in the magnetotail and by what process anon-local population of electrons is energized.Observation:On 15 February 2008 there was a large substorm duringwhich time three of the THEMIS satellites were grouped in the near- Earth tail ,the THEMIS spacecraft provided burst-mode plasma wave observations.Fig1:The top panelshows the three components of the magnetic field .Fig2:The second panel shows energy fluxes of energetic electrons observed by the solid-state telescope(SST) instrument 。

巴黎综合理工考试试题类型(物理)

ECOLE POLYTECHNIQUE – « INGENIEUR POLYTECHNICIEN »PROGRAMINTERNATIONAL ADMISSIONSRecommended knowledge in Physical SciencesThe recommended knowledge in Physical Sciences for the applicants to the “Track 2 - International admissions” is detailed below.This document is meant to give the applicants directions on the knowledge they are likely to be interviewed upon. It is given for information purposes only and cannot be considered as a basis of the programme for the second track examinations.Ecole Polytechnique reserves the right to test an applicant’s knowledge on other fields of Physical Sciences than those listed in this document.Besides, Ecole Polytechnique expects the applicants to know the numerical values of the basic constants of physics, as well as the orders of magnitude of the physical phenomena of nature.The applicants should be able to show excellent standard mathematical skills.An excellent level in mathematics and in physical sciences is a key to successful studies at Ecole Polytechnique.I. MECHANICS¾Newtonian mechanics¾Mechanics of solids¾Statics and mechanics of fluids¾Applications of mechanicsII. ELECTRIC CIRCUITSIII. ELECTRICITY AND MAGNETISM¾Electrostatics¾Magnetostatics¾Electromagnetic wavesIV. OPTICS¾Geometrical optics¾Wave opticsV. THERMODYNAMICS¾Perfect gas¾First and second principles of thermodynamicsPhysical constantsThe values of Planck, Boltzmann and Avogadro constants, the charge and the mass of the electron, the speed of light in vacuum, the electric permittivity and the magnetic permeability of free space, in SI system of units (at least two significant digits are required).Orders of magnitudeThe orders of magnitude of quantities such as the magnetic field of the Earth, the radius of the Earth, the acceleration of free fall at the Earth’s surface, the concentration of electrons in a typical metal, the wavelengths of the electromagnetic waves of the visible spectrum, the distance between two atoms in a solid or liquid, the Bohr radius of the fundamental state of the hydrogen atom, the size of the nucleus.Compulsory minimal requirements of calculation skillsMastering a certain number of calculation skills such as is compulsoryExpansionsBe able to study the behaviour of a physical quantity A (x ) in the neighbourhood of a given value of its argument x . The common expansions about x ≈ 0()()()22111;)1ln( ; 22131cot ; 33tan ; 221cos ; 63sin x x x x x x x x e x x x g x x x x x x x x −++≈+≈+++≈−≈+≈−≈−≈αααα Derivatives and primitives of the functions of a single variableDerivatives of the elementary functions (x g x tg x x x e x n x cot , ,cos ,sin , ,ln ,) as well as of the composition function f (g (x )).Rules for the derivative of the product and the quotient of two functions of a real variable. Primitives of the elementary functions above.Integration by parts.Conditions for the convergence of an integral in the cases of an infinite integration interval or the presence of points of discontinuity.Functions of several variables. Common differential operators.Total differential.Partial derivatives with respect to an independent variable in the case of a function of several variables. Nabla operator ∇. Gradient of a function f (r ). r r ∇ f Curl of a vector field A (r ). Divergence A ×∇r A .∇r . Circulation ∫)(.C d l A .Laplacian and vector Laplacian .f 2∇A 2∇ Multiple integrals. Stokes, Gauss – Ostrogradski theorems.Reduction of multiple integrals to simple integrals by using the symmetry properties (cylindrical, spherical) of the integrants and surfaces (volumes) involvedStokes theorem.Gauss-Ostrogradski theorem.Differential equationsSolution of first order differential equations with separable variables.Solution of second order linear and homogeneous differential equations with constant coefficients. Characteristic polynomial, number and nature of solutions, critical damping.Solution of second order linear inhomogeneous equations with constant coefficients. Concepts of forced oscillations and resonance.Equations with partial derivativesD’Alembert’s solution of the wave equation.Progressive monochromatic plane waves. Concepts of wave vector, wavelength, frequency and period.Principal phenomenological laws (Fick, Fourier and diffusion equations). Energy, mass, etc. balance within an elementary volume.Linear algebraCalculation of a determinant, diagonalization of a matrix, concepts of eigenvalues and eigenvectors of a linear operator.TrigonometryDefinitions and properties of the basic trigonometric functions (sine, cosine, tangent, cotangent).Common trigonometric formulas (cos 2x = cos 2x - sin 2x ; sin 2x = 2 sin x cos x ; sin α + sin β = 2 sin [(α + β ) / 2] cos [(α - β) / 2] ; cos α + cos β = 2 cos [(α + β) / 2] cos [(α - β) / 2], etc.).Fourier series of a regular enough periodic function.I. MECHANICSNewtonian mechanicsNewton’s laws: the principle of inertia, the principle of action and reaction, the fundamental equation of dynamics.Galilean relativity. Concept of non-inertial reference frames and forces referred to as « inertia » forces (in particular, in the case of linear acceleration and uniform rotation frames) Angular momentum theorem. Kinetic energy theorem. Momentum theorem.A two particle system. Central force motion, bound states, scattering states.Expressions for the velocity and the acceleration of a material point in cylindrical and spherical co-ordinates.Concept of potential energy. Independence on the path of the work done by a potential-derived force.Conservation of mechanical energy of an isolated material system in the case of conservative forces.Conservation of angular momentum in the case of central forces. First and second Kepler’s laws (the law of conical sections and the law of areas).Conservation of momentum in the case of an isolated system. Elastic and inelastic collision problems. Concept of a centre of mass of a system.Expressions for the potential, kinetic and total energy of a particle in the case of a circular trajectory.Mechanics of solidsRigid bodies (non-deformable solids). Solids rotating about a fixed axis. Moment of inertia of a rigid body. Expression for the kinetic energy of a rigid body as a sum of a translational term of its centre of mass and of a rotational term referred to the centre-of-mass reference frame (Koenig’s theorem). The problem of the compound pendulum.Statics and mechanics of fluidsEuler’s description (the concept of a velocity field) of a fluid. Concepts of flow density, mass flow rate and volume flow rate. Mass balance. Equation of the conservation of mass in its local form.Definitions of a stationary flow, of an incompressible flow, of a non-rotational flow.Perfect flows: Euler’s equation, Bernoulli’s relationship on incompressible and homogeneous flows.Calculation of the resulting force of the pressure forces exerted upon an object, in fluid statics. The Archimedes’ principle (the buoyancy force applied to an object immersed in a fluid).Applications of mechanicsLorentz force (force exerted on a charged particle in constant electric and magnetic fields). Trajectory of a charged particle in a static and uniform magnetic field.Linear oscillations; damped harmonic oscillations. Forced oscillations, resonance.II. ELECTRIC CIRCUITSElectric voltage. Kirchoff’s laws of knots and meshes. Electric current. Ohm’s law. Superposition theorem.Basic circuit components: resistor, capacitor, coil. Their impedances in sinusoidal regime. Transient regime of charging and discharging a capacitor.Sinusoidal currents and voltages. Maximum value, rms (root mean square) value. Impedances in series and in parallel.Study of resonances in circuits in sinusoidal regime. RLC circuit. Relation to resonance in mechanics.III. ELECTRICITY AND MAGNETISMElectrostaticsCoulomb’s law. The concept of electric field. Electrostatic field E. Circulation and flow of E. Gauss’ theorem. Symmetry properties of E.Electrostatic potential φ and Poisson’s equation.Calculation of E and φ for a simple charge distribution ρ. Electrostatic potential between the plates of a planar capacitor.Concept of electric dipole, field created by a dipole at large distances, interaction energy of a permanent dipole with the electric field. Definition of the electric polarization vector. Electric field in a conductor at equilibrium. Equipotential surfaces.Electric field in the vicinity of a metal surface.Coulomb’s law between two charges immersed in a homogenous linear and isotropic dielectric medium.MagnetostaticsMagnetic field B. Symmetry properties of B.Magnetic field created by a thin wire carrying a current (Biot-Savart law), the two Maxwell equations (the divergence of B and Ampère’s law), vector potential A.Non-unicity of the electrostatic potential φand the vector potential A, unicity of the electric field E and the magnetic field B.Circulation of B. Relationship between the circulation of B and the encircled currents (theorem of the total current).Calculation of B created by straight wires and circular loops. Field along the axis of a circular loop and of a coil (solenoid) having a circular cross-section.Magnetic dipole and magnetic moment M. Expression for the interaction energy between a magnetic moment and a magnetic field B.Flux of B. Electromagnetic induction phenomenon, Faraday’s law, Lenz’ rule.Electromagnetic wavesElectromagnetic waves in vacuum.Maxwell’s equations in vacuum. Progressive harmonic plane waves as solutions of the Maxwell’s equations in vacuum. Frequency, wavelength, wave vector. The concept of phase velocity.Transversality of the electric and magnetic fields.The state of polarization state an electromagnetic wave. Linear and circular polarizations. Volume density of the electromagnetic energy, Poynting vector.Concept of wave packet. Group velocity.Electromagnetic waves in matter (linear and isotropic medium).Macroscopic E and B fields. Constitutive relationships complementing Maxwell’s equations. Frequency-dependent complex dielectric constant ε(ω).Concepts of complex refraction index, dispersion and absorption.Microscopic models describing the material polarization of the medium: Drude model, model of the elastically bound electron (Lorentz model).IV. OPTICSGeometric opticsConcept of light ray. Reflection and refraction by a plane mirror. Snell-Descartes’ laws. Limit angle. The total reflection phenomenon.Spherical mirrors, lenses, conjugation and magnification relations.Wave opticsReflection and refraction of a harmonic progressive polarized plane wave at the interface between two dielectric media. Proof of Snell-Descartes laws.Concept of optical path. Interference between two totally coherent waves. Michelson’s interferometer. Thin slabs. Fabry-Pérot cavity.Diffraction at infinity. Huyghens-Fresnel principle. Diffraction by a rectangular slit. Diffraction at infinity by two slits (Young’s slits), by a row of slits.V. THERMODYNAMICSThermodynamic state functions: internal energy, entropy, enthalpy, free energy, free enthalpy, as well as their differentials.Extensive and intensive variables, thermodynamic equilibrium.Heat capacities at a constant volume and at a constant pressure.Perfect gasPerfect monoatomic gas model. Maxwell-Boltzmann distribution of velocities for a monoatomic perfect gas. The equipartition theorem.Collisions against a wall. Relationship between pressure and mean square velocity.Perfect gas in a field of forces having a potential energy V(r). The barometric formula. Limitations of the perfect gas model. Real gases. The van der Waals gas.First and second principles of thermodynamicsFirst principle. Internal energy U. Heat transfer. Work exchanged by a system. The work of pressure forces. Enthalpy and Joule-Thomson expansion. The enthalpy of a perfect gas. Second principle. The entropy S. Entropy balance. Reversible and irreversible processes. Thermodynamic definition of temperature.The entropy of a perfect gas (for a condensed and idalatable phase).Heat machines. Dithermal cycle. Efficiency. Carnot’s theorem.Equilibrium between the phases of a pure substance. Triple point, critical point, enthalpy and entropy of phase changes. Clapeyron’s formula.Free energy and free enthalpy: definitions and differentials. Chemical potential. The perfect gas case. Equilibrium between two phases. Generalization, Gibbs’ phase rules.。

昆明2024年10版小学五年级上册A卷英语第1单元测验试卷

昆明2024年10版小学五年级上册英语第1单元测验试卷考试时间：80分钟（总分:140）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题共100分)1. 选择题：What do we call the solid form of water?A. LiquidB. GasC. IceD. Vapor答案:C2. 填空题：I saw a _______ (蜥蜴) basking in the sun.3. 填空题：Making a ______ (切花) arrangement can beautify your home.4. 听力题：I can ___ my homework. (finish)5. 听力题：In an electrochemical cell, oxidation occurs at the ____ electrode.6. 选择题：What do you call a house made of ice?A. IglooB. HutC. CabinD. Tent答案:A7. 听力题：An organic compound contains ______.8. 填空题：The __________ in the air feels fresh after the rain. (气息)9. 听力题：A solute is a substance that is ______ in a solution.10. 听力题：The library has _____ (many/few) books.11. 听力题：The _______ helps to keep the soil healthy.12. 填空题：The __________ (历史的讨论) fosters dialogue.13. 选择题：What do we call the largest land animal?A. GiraffeB. ElephantC. RhinoD. Hippo答案:B14. 听力题：The _____ (bunny) hops away.15. 填空题：The otter uses rocks to crack open _______ (贝壳).16. 选择题：What is the largest land animal?A. TigerB. HippoC. ElephantD. Giraffe答案:C17. 填空题：The turtle can survive for long periods without ______ (水).18. 选择题：What do we use to write on a chalkboard?A. PenB. PencilC. ChalkD. Marker答案:C19. 听力题：We have a test on __________.20. 听力题：The Great Red Spot on Jupiter has been raging for hundreds of ______.21. 听力题：My sister loves to ________.22. 选择题：What do you call a triangular-shaped snack made of corn?A. TortillaB. WaffleC. BiscuitD. Cracker答案:A23. 选择题：What do we call the person who creates music?A. AuthorB. ComposerC. PainterD. Architect答案:B24. 听力题：An exoplanet is a planet that orbits a ______ outside our solar system.25. ts are known for their ability to produce ______ and attract beneficial insects. (某些植物因其能产生花蜜而著称，吸引有益昆虫。

一种小型化宽频双极化基站天线辐射单元的仿真设计

一种小型化宽频双极化基站天线辐射单元的仿真设计唐雨果【摘要】基于设计一种小型化的宽频双极化基站天线辐射单元的目的,采用减少辐射单元尺寸的方法实现小型化,应用阻抗匹配优化辐射单元的电压驻波比,利用局部不对称设计等优化方法提高交叉极化比和隔离度等参数.通过HFSS软件对天线性能进行了仿真,给出了1.71～2.69 GHz频段的驻波比和隔离度随频率变化的曲线,以及辐射方向图特性参数,最终得到的辐射单元尺寸比常见的宽频双极化基站天线辐射单元尺寸减少32％且性能完全符合移动通信行业标准.%In the paper, a design of a miniaturized broadband dual-polarized dipole base station antenna is presented. The design reduces the radiation unit size to achieve miniaturization, and optimizes the radiation unit voltage standing wave ratio (VSWR) with impedance matching, and adopts partial asymmetry design to improve the isolation and the cross polarization ratio. The paper uses HFSS to simulate the design. The paper presents the VSWR and the isolationcurve in the frequency range of 1.71～2.69 GHz, and presentsradiation pattern characteristics parameters. As a result, the size of the design is reduced by 32％in the same industry standard for mobile communication.【期刊名称】《电子设计工程》【年(卷),期】2017(025)018【总页数】4页(P143-146)【关键词】基站天线;宽频带;小型化;双极化【作者】唐雨果【作者单位】武汉邮电科学研究院湖北武汉430074【正文语种】中文【中图分类】TN92移动通信技术的发展，给人们带来了好处的同时，也带来了一些技术上的问题，其中之一就是移动通信的制式越来越多。

用于室内分布系统的宽带mimo定向天线设计

摘要摘要近年来，移动通讯技术的不断地进步与发展，消费者对移动通信网络的覆盖面积与信号质量提出了更高的要求。

由于现代钢筋混凝土结构的建筑物对室外的基站信号有吸收和屏蔽作用，这样会对无线电波造成很大的传输损耗，因此移动终端在室内接收到的基站信号非常小，这可能导致室内的用户无法正常使用移动终端。

此外，在一些建筑物内，移动终端设备虽然能够正常通话，然而在这些建筑内用户数量比较多，由于基站信道拥挤，所以移动终端上线比较困难。

室内分布天线系统可以将移动基站的信号均匀分布在室内每个角落来解决这一问题，在这种情况下，本文提出了多款应用于室内分布系统的宽带定向天线及其宽带MIMO定向天线。

1. 双频宽带定向电磁偶极子天线设计。

本文通过对传统电磁偶极子天线进行研究，分别提出了双频宽带定向电磁偶极子天线和双频宽带双极化定向电磁偶极子天线，两款天线覆盖了目前国内三大运营商所使用的通信频段0.806~0.96 GHz和1.71~2.69 GHz。

本文提出了采用形寄生枝节来改善电磁偶极子天线低频阻抗匹配的方法以及分析了影响天线低频辐射特性的原因。

按照两款天线的仿真模型，对天线进行了实物加工并且进行了测试，测试结果与仿真结果吻合比较良好，它们均可应用在室内分布天线系统中。

2. 双频宽带双极化定向MIMO天线设计。

首先设计了一款新形式的双频宽带双极化定向电磁偶极子天线，该天线采用寄生金属环加载，并且在地板边缘添加有一定倾斜角度的挡板，该天线在工作频段内具有良好的定向辐射特性、稳定的增益以及良好的交叉极化特性。

在此天线的基础上，用该天线组成了2×2 MIMO阵列，为了调节同极化天线单元之间的隔离度，在每两个天线单元之间引入了不同高度的挡板。

两款天线都覆盖了0.806~0.96 GHz和1.71~2.69 GHz国内的移动通信频段。

同样对两款天线仿真模型进行了加工和测量，测试结果与仿真结果基本吻合。

3. 带有陷波特性的双频宽带双极化定向MIMO天线设计。

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A Magneto-Electric Dipole Witha Modiﬁed Ground PlaneBi Qun Wu and Kwai-Man Luk ,Fellow,IEEEAbstract—A wideband unidirectional antenna element com-posed of a magnetic dipole and an electric dipole is designed.Simulated and measured results are presented.The antennaachieves an impedance bandwidth of 91%(SWR2).Due to the complementary nature of the antenna and the incorporation of a modiﬁed grounded structure,the antenna has a relatively stable broadside radiation pattern with low cross-polarization and low back-lobe radiation over the operating band.The gain of antenna is about 9.3dBi.Index Terms—0-shaped strip feed,magneto-electric dipole an-tenna,wideband antenna.I.I NTRODUCTIONTHE development of various wireless systems creates a high demand for wideband and low-proﬁle unidirectional antennas,which can accommodate several wireless communi-cation systems with good electrical characteristics,such as low cross-polarization,low back-lobe,and stable gain across the entire bandwidth.Many designs were proposed in literature.The L-probe feed patch antenna can achieve an impedance bandwidth of 35%and an average gain of 7.5dBi [1].The slot antenna can be operated with an impedance bandwidth of 17%-40%[2],[3].These antennas are unstable in antenna gain and asymmetric in radiation pattern over operating band.Recently,a wideband complementary antenna (about 43.3%impedance bandwidth operating at 2.5GHz)designated as the magneto-electric dipole was proposed by Luk et al.[4],[5].The antenna comprises a vertically oriented quarter-wave shorted patch and a horizontal planar dipole,which are equivalent to a combination of a magnetic dipole and electric dipole.Good electrical characteristics such as low back radiation,stable antenna gain over the operating band,andsymmetric -and -plane radiation patterns were demonstrated.Moreover,the size of the magneto-electric dipole can be reduced [6],and two magneto-electric dipole elements can be integrated to form a wideband dual-polarized antenna with good electrical characteristics [7].In this letter,a wideband unidirectional antenna element com-posed of a magnetic dipole and an electric dipole together with aManuscript received January 16,2009;revised March 05,2009.First pub-lished May 15,2009;current version published July 09,2009.This work was supported in part by a grant from the Research Grant Commerce of the Hong Kong Special Administration Region,China (Project No.CityU 119008).The authors are with the State Key Laboratory of Millimeter Waves,Depart-ment of Electronic Engineering,City University of Hong Kong,Kowloon,Hong Kong (e-mail:50538940@.hk).Color versions of one or more of the ﬁgures in this letter are available online at .Digital Object Identiﬁer 10.1109/LAWP.2009.2022964modiﬁed grounded structure is investigated.In the proposed de-sign,the -shaped feed is modiﬁed to enhance the impedance bandwidth.The grounded structure is shaped for stabilizing the radiation pattern and antenna gain.The proposed antenna can achieve about 91%impedance bandwidth with stable radiation pattern,low back-lobe,and stable antenna gain.II.A NTENNA D ESCRIPTION AND D ESIGN G EOMETRY The geometry of the wideband unidirectional antenna ele-ment is shown in Fig.1with detailed dimensions for opera-tion at around 4GHz.The dimensions were selected after a de-tailed parametric study for good performance.The antenna ele-ment can be considered as a combination of a magnetic dipole and an electric dipole.The pair of the upper trapezoidal-shaped patches acts as an electric dipole.Each trapezoid has dimensionof 5.8(),43.3(),and 18.8mm()for the upper base,bottom base,and height,respectively(“”refers to the operating frequency of the antenna).Each slant edge of a trapezoid is connected to a vertical patch,which has a size of29.2mm()24.0mm().The vertical patches are mounted on the modiﬁed ground plane.Each pair of two vertical patches belonging to the same pair of trapezoids is con-nected together to form a right-angle corner vertical wall.The two pairs of the right-angle corner vertical wall act like a mag-netic dipole to produce radiation.When an electric dipole and a magnetic dipole are excited simultaneously,they can produceequal -and -plane radiation patterns [8].The -shaped strip feed consists of two portions,a transmis-sion line and a coupled strip.The transmission line,which is a linear tapered microstrip line,is located close to the corner of a bent vertical wall.The remaining coupling strip,which is L-shaped,can be adjusted for impedance matching [6].The feeding strip is not connected physically to the second dipole arm.It enters into the trapezoidal-shaped hole of second dipole arm without touching the metal.Similar to the conventional mi-crostrip line,the characteristic impedance of the microstrip line with a folded ground plane can be adjusted by tuning the width of the line and the distance from the corner of the folded ver-tical wall.The SMA connector located under the ground plane is connected to the end of the linear tapered line.III.A NTENNA P ERFORMANCE AND A NALYSISA prototype with dimensions shown in Table I was fabri-cated and tested.Simulation results of SWR,isolation,radiation pattern,and gain were obtained by the commercial EM soft-ware IE3D.Experimental results were measured by an Agilent network analyzer and SATIMO antenna measurement system.1536-1225/$25.00©2009IEEEFig.1.Geometry of the proposed antenna.(a)Photograph of the wideband magneto-electric dipole with modiﬁed ground plane.(b)Geometry of the modiﬁed ground plane.(c)Geometry of the wideband magneto-electric dipole.(d)Side view of the 0-shaped feed.Fig.2depicts the SWR and antenna gain versus frequency.It is observed that the measured impedance bandwidth is 91.6%()ranging from 3.05to 8.2GHz,which is much better than most of the complementary wideband antenna de-signs found in the literature [4]–[7].Besides,the measured av-erage gain is about 9.3dBi,and the 3-dB gain operatingbandFig.2.SWR and antenna gain versusfrequency.Fig.3.Simulated and measured radiation patterns.extends from 3.1to 8.5GHz.The simulated and measured radia-tion patterns of the antenna at frequencies of 3,5,and 7GHz are plotted in Fig.3.It can be observed that both of the cross-polar-ization and back-lobe levels are suppressed across the operating band.The measured antenna gain is within 3dB over the en-tire bandwidth.When the size of the ground plane is reduced,the impedance bandwidth and the broadside radiation pattern doWU AND LUK:A MAGNETO-ELECTRIC DIPOLE WITH A MODIFIED GROUND PLANE 629TABLE ID IMENSIONS OF P ROPOSED ANTENNATABLE IIT HE 3-dB B EAMWIDTH AND F RONT -TO -B ACK RATIOnot change signiﬁcantly,whereas the back-lobe level and gain deteriorate.The effective size of the ground plane in terms of wavelength can be stabilized by modifying its structure as the current ﬂow in it is changed with frequency.Finally,it should bementioned that the performance of the antenna is insensitive to the dimensions of gap and height,which conﬁrms the robustness of the design.Good agreement was observed between simula-tion and measurement results.IV .C ONCLUSIONA wideband unidirectional antenna element composed of a magnetic dipole and an electric dipole has been designed and measured.The antenna achieves an impedance bandwidth of91%().Due to the complementary nature of the an-tenna and the incorporation of a modiﬁed grounded structure,the antenna has a relatively stable broadside radiation pattern with low cross-polarization and low back-lobe radiation over the operating band.The gain of antenna is about 9.3dBi.R EFERENCES[1]K.M.Luk,C.L.Mak,Y.Chow,and K.F.Lee,“Broadband microstrippatch antenna,”Electron.Lett.,vol.34,pp.1442–1443,1998.[2]A.A.Eldek,A.Z.Elsherbeni,C.E.Smith,and K.F.Lee,“Wide-band slot antenna for radar applications,”in Proc.IEEE Radar Conf.,Huntsville,AL,May 2003,pp.79–84.[3]M.Miao,B.L.Ooi,and P.S.Kooi,“Broadband CPW-fed wide slotantenna,”Microw.Opt.Technol.Lett.,vol.25,no.3,pp.206–211,May 2000.[4]K.M.Luk and H.Wong,“A complementary wideband antenna,”U.S.Patent No.11/373,518,Mar.10,2006.[5]K.M.Luk and H.Wong,“A new wideband unidirectional antenna ele-ment,”Int.J.Microw.Opt.Technol.,vol.1,no.1,pp.35–44,Jun.2006.[6]L.Siu and K.M.Luk,“Unidirectional antenna with loaded dielectricsubstrate,”IEEE Antennas Wireless Propag.Lett.,vol.7,pp.50–53,2008.[7]K.M.Luk and L.Siu,“A dual-polarized magneto-electric dipole withloaded dielectric substrate,”in Proc.iWAT2008,Chiba,Japan,IT22.[8]A.Clavin,“A new antenna feed having equal E -and H -plane patterns,”IRE Trans.on Antennas and Propag.,vol.AP-2,no.3,pp.113–119,Jul.1954.。