Graphics Programs Reference
In-Depth Information
ó
x
ó
y
where
and
are unit vectors along the x and y directions, respectively. At
z
=
0
,
E
x
=
E
1
sin
ω()
and
E
y
=
E
2
sin
(
ω
t
+
δ
)
, then by replacing
sin
ω()
by the ratio
E
x
⁄
E
1
and by using trigonometry properties Eq. (11.9)
can be rewritten as
E
2
E
2
E
2
E
2
2
E
x
E
y
cos
E
1
E
2
δ
)
2
-----
---------------------------
+
-----
=
(
sin
δ
(11.10)
Note that Eq. (11.10) has no dependency on
ω
t
.
In the most general case, the polarization ellipse may have any orientation,
as illustrated in
Fig. 11.10
.
The angle
ξ
is called the tilt angle of the ellipse. In
this case, AR is given by
OA
OB
AR
=
--------
(
1
≤≤
AR
∞
)
(11.11)
When , the wave is said to be linearly polarized in the y direction,
while if the wave is said to be linearly polarized in the x direction.
Polarization can also be linear at an angle of when and
. When and , the wave is said to be Left Circu-
larly Polarized (LCP), while if the wave is said to Right Circularly
Polarized (RCP). It is a common notation to call the linear polarizations along
the x and y directions by the names horizontal and vertical polarizations,
respectively.
E
1
=
0
E
2
=
0
45°
E
1
=
E
2
ξ
=
45°
E
1
=
E
2
δ
=
90°
δ
=
90°
Y
E
2
E
y
A
E
B
X
ξ
E
x
O
E
1
Z
Figure 11.10. Polarization ellipse in the general case.
Search WWH ::
Custom Search