Transcript 第四章天线基本参数及仿真设计

第四章 天线基本参数及仿
真设计
西南石油大学
韦国晖
理学院
天线基本参数
• Radiation Pattern 2D & 3D Plot
3-D plot
( both θ and ϕ vary )
2-D plot
( θ= const plane, ϕ vary or
ϕ= const plane, θ vary )
Some concepts related to the pattern
terminology-1
a) 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.
b) 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.)
c) 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. singlewire antennas).
Some concepts related to the pattern
terminology-2
d)
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
e) 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
pattern’s 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
pattern’s origin and tangent to the main beam at its base. It very often approximately
true that FNBW≈2⋅HPBW.
The HPBW is the best parameter to describe the
antenna resolution properties..
天线辐射强度(Antenna Radiation intensity)
a) 立体角（Solid angle）In
spherical coordinates
d   sin  d d , sr
b) 辐射强度U
（Radiation intensity U ）
d  rad
U
, w/sr
d
 rad 
 Ud 
4
, w
U  r2  P
c) 辐射功率密度P（radiation
power density P）
d
P
, W/m2
ds
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
r2 2
U ( ,  ) 
E
2
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