第六章 平面电磁波
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 PresentationTRANSCRIPT
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5: electromagnetic waveX
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6.1
(homogeneous)()( )isotropic( )
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5 6-1 6-2 xy6-1
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xy6-1 6-3 6-4 : z (z): z(z) , z(traveling wave
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6-5 6-6 : 6-7
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6-8 wave impedanceintrinsic impedance free space 6-8 6-9 6-86-6
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6-8 6.1.2 (1)EH Transverse Electro-Magnetic waveTEM (2)EH 6-9
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(3) 6-7 6-10 (plane of constant phase) plane wavexy uniform plane wave
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6-16-10 phase speed const
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=0 6-11
6-11 6-12 kwave-numberkz kk(phase constant)
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k (4) (6-7)(6-8) (6-13) (5) :
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6-14 T
6-2 6-136-146-15
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(6) 6-16a 6-16b 6-16c 6-16d
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6.2 ()
(6-17a)
(6-17b)
(6-17c) (6-17d)
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5 (6-17e) 6-17d 6-18 6-19a 6-19b
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: (). 6-17
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6-20a
6-20c
6-20d 6-20bpropagation constant6-20TEM
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6-20c
6-21a 6-21b x
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6-22a
6-22b
6-23a
1dBNp (dB) 6-24a
6-22c6-23battenuationconstant
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(Np) 6-24b 1Np 1Np8.686dB/(Np/m)/(dB/m) 26-23 6-25 phase constant
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k
(3)6-26a6-26b
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6-4
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(4) 6-27
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915MHz2450MHz5800MHz22125MHz915MHz2450MHz(5)
6-28a
6-28b
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: (6)
6-26
6-29
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7 6-30a
6-30b
6-30c
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=5.8107 S/m=6.15107 S/m 16-21 6-20d 6-31a 6-31b 6-31c
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2 6-32vpvp106Hzvp=415m/sn 6-33
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107skin effectdepth of penetration36.8% 6-34
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6-150Hz464kHz10GHz6-34mm
m
m
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,)
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6-250Hz105HzS/m 105Hz
m m
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6-31c 3
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6-5 z ( 6-5)
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x 6-35surface resistivity
6-36
6-37
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6-5z H0
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W/m2 6-38 6-5L 6-39
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a 6-40a 6-40b
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Q 1 (dispersive):
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2 v,c 1 t ,
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,2
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EnvelopeGroupVelocity6-41
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6-41 3
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6-42
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6.3
zxyxy 6-43 6-44a 6-44b () ExmEym
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polarization
1x6-45
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Elinear polarization6-6
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2 =E 6-46a
x
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z circular polarization right-handed circularly polarized wave left-handed circularly polarized wave6-7 z ,
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6-8azz6-8bz
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3 6-446-44
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6-47 6-9elliptical polarization
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,6-44 :
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6-6-2
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6.4 . 6-10z transmitted wave,reflected wave.
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6-10()()zx 6-48a 6-48b x
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6-49a 6-49b6-486-49 6-50 6-51a 6-51b6-52a
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6-53a 6-53b: nodal point loop point6-52b 6-536-11
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standing wave
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6-54
6-552
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6-56a 6-56b 6-56c
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6-10 ( )( )xz x (6-48)(6-49) 6-57a 6-57b
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6-58a 6-58breflection coefficient R T
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6-58 6-59a 6-59b 6-59c 6-60a 6-60b 6-60c 6-60d
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6-60a6-60b6-61a 6-61b 6-12
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n=012 6-62a 6-62b 6-62c 6-62d
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6-63
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: z: standing wave ratio 6-64a 6-64b 6-60a6-60b z6-65a
- z 6-65b z z (z
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6-31c 6-59a
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(6-67)
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z 6-76a 6-76b kz=z=z6-15a z 6-77 6-15b
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6-78a 6-78b
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6-78c 6-78d 6-78e kPropagation Vector 6-78a
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z 6-79 z z6 -16AP
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,oblique incidenceplane of incidence. parallel polarized wave
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1 6-17a xz . 6-80a 6-80b
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y 6-80c 6-80d
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refracted wave 6-80e 6-80f 6-81 xy 6-82a 6-82b
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6-82b6-82b
6-83a 6-83b :
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6-82b
6-84 (Snell),
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6-82arefraction coefficient 6-85a 6-85b (A. J. Fresnel) 6-85c
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2.
6-17b 6-86a 6-86b 6-86c
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6-87a 6-87b 6-18 Brewster Angle 6-87a 6-88 6-85a
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6-89
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1 6-19axz 6-90 6-91a
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6-91b
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(1)xTransverse Electric waveTEx 6-92 x
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(2)zz (3) .y ,,4TE
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(4) 6-93 x 6-94 x x (5) 6-95
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2 6-19b 6-86 6-96 6-97a 6-97b 6-97c
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90o critical angle xzTransverse Magnetic waveTM 6-98
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6-896-87a1total reflection