导电媒质中的平面波2(双语)
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π
difference of 2 , but the same amplitude Em, i.e.
Ex (z,t) ex Em sin( t kz)
E
y
(
z,
t)
e
y
Em
sin(
t
kz
π 2
)
ey
Em
cos(
t
kz)
Then the instantaneous value of the resultant wave 合成波
a
π 2
(
t
kz)
At a given point z the angle is a function of time t. The direction of the electric field intensity vector is rotating with time, but the magnitude is unchanged. Therefore, the locus of the tip of the electric field intensity vector is a circle, and it is called circular polarization 圆极化 .
is
E(z, t)
Leabharlann Baidu
Ex2 (z, t)
E
2 y
(
z,
t
)
Em
The direction of the resultant wave is at an angle of to the x-axis,
and
tan
Ey (z,t) Ex (z,t)
cot(
t
kz)
tan[
π 2
(
t
kz)]
i.e.
between the field vector and the x-axis is
yy
tan
Ey (z,t) Ex (z, t)
E ym Exm
Ey
E
Ey
E
Ex O O ExEx
xx
E
Ey
The polarization direction of the resultant electric field is independent of time, and the locus of the tip of the electric field intensity vector over time is a straight line at an angle of to the x-axis. Thus the resultant field is still a linearly polarized wave 线极化波 .
Conversely, a linearly polarized plane wave can be resolved into 分 解 two orthogonal, linearly polarized plane waves of the same phase but different amplitudes.
4. Polarizations 极化 of Plane
WaveTshe time-varying behavior of the direction of the electric field intensity is called the polarization of the electromagnetic wave.
The instantaneous value of the electric field intensity of another plane wave of the same frequency is
E y (z, t) ey Eym sin( t kz)
This is also a linearly polarized plane wave, but with the electric field along the y-direction.
E(z,t)
Ex2 (z,
t)
E
2 y
(
z,
t)
Ex2m
E
2 ym
sin(
t
kz)
The time-variation of the magnitude of the resultant 合成
electric field is still a sinusoidal function, and the tangent of the angle
If the above two orthogonal 正交 , linearly polarized plane waves with the same phase but different amplitudes coexist, then the instantaneous value of the resultant electric field is
If the two plane waves have opposite phases and different amplitudes, how about the resultant wave?
If the above two linearly polarized plane waves have a phase
Suppose the instantaneous value of the electric field intensity of a plane wave is
Ex (z, t) ex Exm sin( t kz)
Obviously, at a given point in space the locus 轨迹 of the tip 端 点 of the electric field intensity vector over time is a straight line parallel to the x-axis. Hence, the wave is said to have a linear polarization 线极化 .
If two orthogonal, linearly polarized plane waves of the same phase but different amplitudes are combined, the resultant 合成 wave is still a linearly polarized plane wave.
difference of 2 , but the same amplitude Em, i.e.
Ex (z,t) ex Em sin( t kz)
E
y
(
z,
t)
e
y
Em
sin(
t
kz
π 2
)
ey
Em
cos(
t
kz)
Then the instantaneous value of the resultant wave 合成波
a
π 2
(
t
kz)
At a given point z the angle is a function of time t. The direction of the electric field intensity vector is rotating with time, but the magnitude is unchanged. Therefore, the locus of the tip of the electric field intensity vector is a circle, and it is called circular polarization 圆极化 .
is
E(z, t)
Leabharlann Baidu
Ex2 (z, t)
E
2 y
(
z,
t
)
Em
The direction of the resultant wave is at an angle of to the x-axis,
and
tan
Ey (z,t) Ex (z,t)
cot(
t
kz)
tan[
π 2
(
t
kz)]
i.e.
between the field vector and the x-axis is
yy
tan
Ey (z,t) Ex (z, t)
E ym Exm
Ey
E
Ey
E
Ex O O ExEx
xx
E
Ey
The polarization direction of the resultant electric field is independent of time, and the locus of the tip of the electric field intensity vector over time is a straight line at an angle of to the x-axis. Thus the resultant field is still a linearly polarized wave 线极化波 .
Conversely, a linearly polarized plane wave can be resolved into 分 解 two orthogonal, linearly polarized plane waves of the same phase but different amplitudes.
4. Polarizations 极化 of Plane
WaveTshe time-varying behavior of the direction of the electric field intensity is called the polarization of the electromagnetic wave.
The instantaneous value of the electric field intensity of another plane wave of the same frequency is
E y (z, t) ey Eym sin( t kz)
This is also a linearly polarized plane wave, but with the electric field along the y-direction.
E(z,t)
Ex2 (z,
t)
E
2 y
(
z,
t)
Ex2m
E
2 ym
sin(
t
kz)
The time-variation of the magnitude of the resultant 合成
electric field is still a sinusoidal function, and the tangent of the angle
If the above two orthogonal 正交 , linearly polarized plane waves with the same phase but different amplitudes coexist, then the instantaneous value of the resultant electric field is
If the two plane waves have opposite phases and different amplitudes, how about the resultant wave?
If the above two linearly polarized plane waves have a phase
Suppose the instantaneous value of the electric field intensity of a plane wave is
Ex (z, t) ex Exm sin( t kz)
Obviously, at a given point in space the locus 轨迹 of the tip 端 点 of the electric field intensity vector over time is a straight line parallel to the x-axis. Hence, the wave is said to have a linear polarization 线极化 .
If two orthogonal, linearly polarized plane waves of the same phase but different amplitudes are combined, the resultant 合成 wave is still a linearly polarized plane wave.