Specifications

8
3. Measure the gain flatness or variation over a
frequency range using the following sequence.
First, set the appropriate start/stop or center/span
frequencies over which the flatness is to be meas-
ured. Then perform an appropriate calibration
over this frequency range. Then perform the fol-
lowing to see a direct readout of the peak-to-peak
difference in the trace.
[MARKER]
{MARKER 1}
{MORE} {MARKER TO MINIMUM}
[PRIOR MENU]
{MARKER 2}
{MODE MENU} {REF=1}
{MORE} {MARKER TO MAXIMUM}
Reverse isolation
For the measurement of reverse isolation the RF
stimulus signal is applied to the output of the AUT
by measuring S
12
. External attenuation placed on
the output of the AUT may not be needed for this
measurement since the signal path now exhibits
loss instead of gain. If it is removed, a new calibra-
tion will be required.
1. Recall the full two-port calibration.
[RECALL]
{INST STATE 1}
2. Set up the Agilent 8510C for an S
12
log magni-
tude measurement.
[S12] [LOG MAG]
If the isolation of the AUT is very high (i.e., dis-
played trace is in the noise floor) it may be neces-
sary to remove the external attenuation at the out-
put of the AUT and recalibrate (with a response
and isolation calibration) at a higher power level
and increased averaging.
3. Scale the display for optimum viewing and use a
marker to measure the reverse isolation at a
desired frequency.
Deviation from linear phase
The measurement of deviation from linear phase of
the AUT employs the electrical delay feature of the
8510C network analyzer to remove the linear por-
tion of the phase shift from the measurement.
1. Set up the analyzer for an S
21
phase measure-
ment.
[S21] [PHASE]
Figure 4. Reverse isolation measurement
Figure 5. Deviation from linear phase measurement