
70 MICROWAVE TRANSMISSION LINES
5. From
reflection coefficient
(P):
I+P
VSWR =
(4-51)
1-P
It is also possible to determine the reflection coefficient (P) from knowledge of
VSWR:
VSWR- 1
P = (4-52)
VSWR + 1
The relationship between reflection coefficient (P) and VSWR is shown in Fig. 4-12.
VSWR is usually expressed as a
ratio.
For example, when
ZL
is 100 f2 and
Zo
is
50 f2, the VSWR is
ZL/Zo
= 100 f2/50 f2 = 2, which is usually expressed as VSWR =
2:1. VSWR can also be expressed in decibel form:
VSWRoa = 20 log (VSWR)
(4-53)
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