208
8163A/B, 8164A/B, 8166A/B User’s Guide
7
Return Loss Measurement
The constant
s
is a multiplier giving the scattering factor. The scattering
factor accounts for the directivity of the second coupler, backscatter in the
fiber, and reflections of connectors. The calibration procedure helps you to
eliminate the affect of these on return loss measurements.
For
on page 184, the reflection factor of the
component is known. Here we refer to the reflection factor as
R
Ref
. This
gives the following equation:
For
Measuring the Power when there are No Reflections
value of the reflection factor is zero. This gives the following equation:
For
Measuring the Reflections from the DUT
on page 206, the value of the
reflection factor of the DUT is called
R
DUT
. This gives the following
equation:
If we substitute equation 3 into equations 2 and 4, this gives us the
following two equations:
If we subtract
P
para
from equations 5 and 6, this gives us the following
equations:
P
Ref
c
1
M
Ref
R
Ref
c
2
M
Ref
+
=
(2)
P
para
c
2
M
para
=
(3)
P
DUT
c
1
M
DUT
R
DUT
c
2
M
DUT
+
=
(4)
P
Ref
c
1
M
Ref
R
Ref
M
ref
M
para
---------------
P
para
+
=
(5)
P
DUT
c
1
M
DUT
R
DUT
M
DUT
M
para
---------------
P
para
+
=
(6)
Summary of Contents for 8163A
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Page 86: ...8163A B 8164A B 8166A B User s Guide 85 Additional Information 2 Figure 47 MAC Address...
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Page 298: ...8163A B 8164A B 8166A B User s Guide 297 Applications 10 Figure 183 Low Dynamic Range...
Page 310: ...8163A B 8164A B 8166A B User s Guide 309 Applications 10 Figure 190 Printed Results...
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