第四章 天线基本参数及仿真设计.ppt
第四章 天线基本参数及仿真设计,西南石油大学 理学院韦国晖,天线基本参数,Radiation Pattern 2D&3D Plot,3-D plot(both and vary),2-D plot(=const plane,vary or=const plane,vary),Some concepts related to the pattern terminology-1,等方向模式（Isotropic pattern）is the pattern of an antenna having equal radiation in all directions.This is an ideal(not physically achievable)concept.However,it is used to define other antenna parameters.It is represented simply by a sphere whose center coincides with the location of the isotropic radiator.定向天线（Directional antenna）is an antenna,which radiates(receives)much more efficiently in some directions than in others.Usually,this term is applied to antennas whose directivity is much higher than that of a halfwavelengthdipole.)全向天线（Omnidirectionalantenna）is an antenna,which has a non-directional pattern in a given plane,and a directional pattern in any orthogonal plane(e.g.single-wire antennas).,Some concepts related to the pattern terminology-2,主模式（Principal patterns）are the 2-D patterns of linearly polarized antennas,measured in the E-plane(a plane parallel to the E vector and containingthe direction of maximum radiation)and in the H-plane(a plane parallelto the H vector,orthogonal to the E-plane,and containing the directionof maximum radiation).,Some concepts related to the pattern terminology-3,模式波瓣（Pattern lobe）is a portion of the RP whose local radiation intensitymaximum is relatively weak.Lobes are classified as:major（主波瓣）,minor（副波瓣）,side lobes（旁瓣）,back lobes（后瓣）.,Antenna Pattern beamwidth,Half-power beamwidth(HPBW)is the angle between two vectors,originating at the patterns origin and passing through these points of the major lobe where the radiation intensity is half its maximum.First-null beamwidth(FNBW)is the angle between two vectors,originating at the patterns origin and tangent to the main beam at its base.It very often approximately true that FNBW2HPBW.,The HPBW is the best parameter to describe the antenna resolution properties.,天线辐射强度(Antenna Radiation intensity),立体角（Solid angle）In spherical coordinates,辐射强度U（Radiation intensity U）,In the far-field zone,the radial field components vanish,and the remaining transverse components of the electric and the magnetic far fields are in phase,辐射功率密度P（radiation power density P）,常见的天线结构,天线的分类,作业,制作偶极子天线及半波振子天线阵制作引向天线用方法三制作天线阵,作业要求,保留后缀名为：*.mod的文件若有参数设置，还需保留后缀名为：*.par的文件制作幻灯片，包括：模型图、边界设置图、端口设置图、激励信号图、结果分析图（根据所设计元件的主要特性要求进行选择，并加入分析说明）,天线问题的求解过程,边界设置,场监视器,远场探针,点频远场,天线阵计算方法,
