Keysight Technologies 8163A, Руководство пользователя

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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 Return Loss Measurement 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 on page 205, the
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)