HP 8754A - Return Loss

SWR, standing wave ratio, can be calculated from Return Loss using the HP Reflectometer Calculator
(HP P /N 5952-0948) or these equations:
Connect test device
Set
REFERENCE switch to move trace to reference position line.
Return Loss = REFERENCE switch setting + trace displacement from reference position line.
f.
Model 8754A .
dB Reference
.~"'.
Frequency MHz
Center
•
•
1 + P
1 -p
SWR=
p = lOD where D = Return Loss (dB)
-20
22
Connect a short circuit.
Set
CRT display, frequency sweep, and signal levels.
CHANNEL 1, select:
AIR.
Set REFERENCE switch to -00.
Adjust OFFSET vernier to move trace to reference position line (OFFSET switch in).
MEASUREMENT
CALIBRATION
For example, if the measured magnitude ratio is - 30 dB,
Return Loss = 30 dB, P = 0.032, and the SWR is 1.07.
After calibration, a negative value indicates that the magnitude of the reflected signal is less than the in-
cident signal. This figure shows
return loss of a bandpass filter at 10 dB/division. The reference position
line is set ot the center graticule, REFERENCE switch is set to -17 so the Return Loss at the center hori-
zontal graticule is 17 dB.
Measure Return Loss as follows:
Return Loss
Reflection Measurements
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