Environmental Engineering Reference
In-Depth Information
Fig. 2.4
Schematic of a
microstrip line
ln
8
h
120
π
w
4
h
=
w
+
Z
ms
√
ε
(2.14)
eff
whereas for 1
<
w
/
h
<
20
w
h
+
667
ln
w
h
49
−
1
120
π
Z
ms
=
√
ε
1
.
393
+
0
.
+
1
.
(2.15)
eff
where
ε
eff
is the effective permittivity;
w
is the width of the microstrip; and
h
is the
thickness of the substrate [26].
2.2
Reflected Waves
Let us consider a
Z
0
-impedance TL, terminated with a generic load impedance,
Z
L
(FIg. 2.5). When
Z
L
does not match
Z
0
, part of the incident wave is absorbed by the
load, and the rest is reflected along the line.
Fig. 2.5
TL connected be-
tween the generator and the
load
At any point on the line, the reflected voltage is given by [25]
V
R
=
Γ
V
I
(2.16)
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