Click here to load reader
Upload
theodore-gilliam
View
26
Download
2
Embed Size (px)
DESCRIPTION
第六章 平面电磁波. 第 5 章的麦克斯韦理论表明 : 变化的电场激发变化的磁场,变化的磁场激发变化的电场,这种相互激发、在空间传播的变化的电磁场 称为 电磁波( electromagnetic wave )。 我们所知道的无线电波、电视信号、雷达波束、激光、 X 射线和 射线等等都是电磁波。 电磁波可以按等相位面的形状分为 平面波、柱面波和球面波。 平面波 : 等相位面 是指空间振动相位相同的点所组成的面,等相位面是平面的电磁波; 均匀平面 波是指等相位面上场强处处相等的平面波。. - PowerPoint PPT Presentation
Citation preview
5: electromagnetic waveX
6.1
(homogeneous)()( )isotropic( )
5 6-1 6-2 xy6-1
xy6-1 6-3 6-4 : z (z): z(z) , z(traveling wave
6-5 6-6 : 6-7
6-8 wave impedanceintrinsic impedance free space 6-8 6-9 6-86-6
6-8 6.1.2 (1)EH Transverse Electro-Magnetic waveTEM (2)EH 6-9
(3) 6-7 6-10 (plane of constant phase) plane wavexy uniform plane wave
6-16-10 phase speed const
=0 6-11
6-11 6-12 kwave-numberkz kk(phase constant)
k (4) (6-7)(6-8) (6-13) (5) :
6-14 T
6-2 6-136-146-15
(6) 6-16a 6-16b 6-16c 6-16d
6.2 ()
(6-17a)
(6-17b)
(6-17c) (6-17d)
5 (6-17e) 6-17d 6-18 6-19a 6-19b
: (). 6-17
6-20a
6-20c
6-20d 6-20bpropagation constant6-20TEM
6-20c
6-21a 6-21b x
6-22a
6-22b
6-23a
1dBNp (dB) 6-24a
6-22c6-23battenuationconstant
(Np) 6-24b 1Np 1Np8.686dB/(Np/m)/(dB/m) 26-23 6-25 phase constant
k
(3)6-26a6-26b
6-4
(4) 6-27
915MHz2450MHz5800MHz22125MHz915MHz2450MHz(5)
6-28a
6-28b
: (6)
6-26
6-29
7 6-30a
6-30b
6-30c
=5.8107 S/m=6.15107 S/m 16-21 6-20d 6-31a 6-31b 6-31c
2 6-32vpvp106Hzvp=415m/sn 6-33
107skin effectdepth of penetration36.8% 6-34
6-150Hz464kHz10GHz6-34mm
m
m
,)
6-250Hz105HzS/m 105Hz
m m
6-31c 3
6-5 z ( 6-5)
x 6-35surface resistivity
6-36
6-37
6-5z H0
W/m2 6-38 6-5L 6-39
a 6-40a 6-40b
Q 1 (dispersive):
2 v,c 1 t ,
,2
EnvelopeGroupVelocity6-41
6-41 3
6-42
6.3
zxyxy 6-43 6-44a 6-44b () ExmEym
polarization
1x6-45
Elinear polarization6-6
2 =E 6-46a
x
z circular polarization right-handed circularly polarized wave left-handed circularly polarized wave6-7 z ,
6-8azz6-8bz
3 6-446-44
6-47 6-9elliptical polarization
,6-44 :
6-6-2
6.4 . 6-10z transmitted wave,reflected wave.
6-10()()zx 6-48a 6-48b x
6-49a 6-49b6-486-49 6-50 6-51a 6-51b6-52a
6-53a 6-53b: nodal point loop point6-52b 6-536-11
standing wave
6-54
6-552
6-56a 6-56b 6-56c
6-10 ( )( )xz x (6-48)(6-49) 6-57a 6-57b
6-58a 6-58breflection coefficient R T
6-58 6-59a 6-59b 6-59c 6-60a 6-60b 6-60c 6-60d
6-60a6-60b6-61a 6-61b 6-12
n=012 6-62a 6-62b 6-62c 6-62d
6-63
: z: standing wave ratio 6-64a 6-64b 6-60a6-60b z6-65a
6-31c 6-59a
(6-67)
z 6-76a 6-76b kz=z=z6-15a z 6-77 6-15b
6-78a 6-78b
6-78c 6-78d 6-78e kPropagation Vector 6-78a
z 6-79 z z6 -16AP
,oblique incidenceplane of incidence. parallel polarized wave
1 6-17a xz . 6-80a 6-80b
y 6-80c 6-80d
refracted wave 6-80e 6-80f 6-81 xy 6-82a 6-82b
6-82b6-82b
6-83a 6-83b :
6-82b
6-84 (Snell),
6-82arefraction coefficient 6-85a 6-85b (A. J. Fresnel) 6-85c
2.
6-17b 6-86a 6-86b 6-86c
6-87a 6-87b 6-18 Brewster Angle 6-87a 6-88 6-85a
6-89
1 6-19axz 6-90 6-91a
6-91b
(1)xTransverse Electric waveTEx 6-92 x
(2)zz (3) .y ,,4TE
(4) 6-93 x 6-94 x x (5) 6-95
2 6-19b 6-86 6-96 6-97a 6-97b 6-97c
90o critical angle xzTransverse Magnetic waveTM 6-98
6-896-87a1total reflection