微波技术与天线

sin( )
x2 sin( )
z2 x
x2
z2
x
1 2 2
z2
1 2 2
E
jIl sin e jr 4 r
H
j Il sin e jr 4 r
E Er Hr H 0
S
1 2
E
H
1 2
ar
E
H*
ar
I 2l 2 2 32 2r2
(sin )2
Antenna Pattern 天线的方向图
Antenna Pattern Parameters 描述方向图的参数
Main Lobe - radiation lobe in the direction of maximum radiation. 主瓣：最大辐射方向上的波瓣
Minor Lobe - any radiation lobe other than the main lobe. 副瓣：主瓣以外的其他波瓣
等方向性方向图 – 由等方向性辐射源(点源,非物理上可 实现的唯一的无方向性天线)产生的，在任意方向上辐 射都相同的方向图,
有向方向图
Directional Pattern - a pattern characterized by more efficient radiation in one direction than another (all physically realizable antennas are directional antennas).
有向方向图- 在某些方向上的辐射比其他方向强的方向图 (所有物理可实现的天线都是有向天线).
Omnidirectional Pattern 全向方向图
Omnidirectional Pattern - a pattern which is uniform in a given plane.
全向方向图- 在一个给定的平面内任意方向都相
Isotropic Pattern 等方向性方向图
Isotropic Pattern - an antenna pattern defined by uniform radiation in all directions, produced by an isotropic radiator (point source, a non-physical antenna which is the only nondirectional antenna).
主？瓣
副？瓣
旁？瓣
副？瓣
后？瓣 功率方向图
First null b？eamwidth (FNBW) Half powe？r beamwidth (HPBW)
Common Types of Antenna Patterns 天线方向图的一般类型
Power Pattern - normalized power vs. spherical coordinate position.
功率方向图：基于球坐标的归一化功率图。 Field Pattern - normalized |E| or |H| vs. spherical coordinate position 场方向图：基于球坐标的归一化的电场或磁场的 模值。
e
j
r
r
E
0
H
r
0
H
0
H
j 4
Il r
1
1
j
r
sin
e
j r
intrinsic impedance of the dielectric medium
介质的本征波阻抗
Near-Zone Fields 近区场
Er
Il 2 r 2
1
1
j
r
cos
e
j r
E
jIl 4 r
1
1
j
r
cos
e
j r
jIl 4 r
1
1
jr
1
2r2
sin
e
j
r
0
E
H
jIl sin e jr 4 r j Il sin e jr 4 r
H
r
0
H
0
E Er Hr H 0
H
j 4
Il r
1
1
j
r
sin
e
j r
Spherical polar coordinates 球坐标
同的方向图
E-plane - the plane containing the electric field vector and the direction of maximum radiation. E平面-包含电场矢量和最大辐射方向的平面
H-plane - the plane containing the magnetic field vector and the ቤተ መጻሕፍቲ ባይዱirection of maximum radiation. H平面-包含磁场场矢量和最大辐射方向的平面
Chapter6 Antenna Basics 天线基础
Horn Antenna 喇叭天线
偶极子
反射器
八木-宇田天线
微带（贴片）天线
微带（贴片）天线
天线阵
I
l
I：等幅同相
电基本振子
Er
Il 2 r 2
1
1
j
r
cos
e
j r
E
jIl 4 r
1
1
jr
1
2r2
sin
Side Lobe：旁瓣
Back Lobe - the radiation lobe opposite to the main lobe.
后瓣：与主瓣方向相反的波瓣
Half-Power Beamwidth (HPBW) - the angular width of the main beam at the half-power points. 半功率波束宽度：主波束半功率点之间的夹角
1
1
jr
1
2r2
sin
e
j
r
E
0
H
r
0
H
0
H
j 4
Il r
1
1
j
r
sin
e
j r
Er
j
Il 2 r3
cos
E
j
Il 4 r3
sin
H
Il
4 r2
sin
E Hr H 0
Far-Zone(Radiation) Fields 远区场
Er
E
E
Il 2 r 2
First Null Beamwidth (FNBW) - angular width between the first nulls on either side of the main beam. 第一零点波束宽度：主波束两边第一个零点之间的夹角
First null？beamwidth (FNBW) Half powe？r beamwidth (HPBW)