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This is the return loss calibration routine. It is called
when
return loss measurements
are requested.
When
the prompt appears, connect a short circuit to the test
port of the Reflectometer Bridge and press the CONT
(continue) key. Next, connect a shielded open to the
test port and press the CONT key. A shielded open is
preferable to an open connector at high frequencies
(above 12 GHz) because it radiates less power and so
behaves more like an ideal open circuit.
RETURN
LOSS
CALIBRATION
Connect
a
SHORT
circuit
to
the
Test
Port
and
rpress
CONT.
Takina
data...
Connect
a
shielded
OPEN
circuit
to
the
Test
Port
and
rress
CONT
Takins
data. ..
This is the insertion loss/gain calibration routine. It
is called when
insertion
loss measurements
are re-
quested. Connect the "B" detector to the test port of
the bridge and press the CONT key.
INSERTION
LOSS
CALIERATION
Connect
the
B
detector
to
the
Test
Port
and
press
CONT.
Taking
data...
Connect the device under test (DUT) to the test port.
If measuring insertion loss, connect the "B" detector to
the output of the device. The test device must be ter-
minated with a detector or load resistor even when
making only return loss measurements. When
measur-
ing high return loss on a two-port device, a good load
resistor should be used to terminate the device. The
data output may
be labeled
with any combination
of
letters and numbers up to 32 characters. After entering
the label, press the END LINE key.
DEVICE
MERSUREMENT
Cannect
the
Test
Device
to
the
Test
Port
and
press
CONT.
Enter
the
Device
label
(ur
to
22
alrhanumeric
characters)
and
press
the
END
LINE
kex.
2
Takins
data...
This menu appears after the test data has been taken.
The data may be plotted or displayed on the screen of
the HP 85A, or printed on the internal printer. The
NEXT
key (k4) will begin another measurement
se-
quence using the same frequency points and calibration
data. To redefine the measurement parameters, select
the RESTART
key (k8). New
calibration data is taken
when the RESTART key is selected.
SELECT
FUNCTION
ki:
PLOT
data
and
halt
rrosram
Press
(COPY)
for
hard
rlot.
Press
(CONT)
to
resume.
k&:
DISPla»
tabular
data.
kZ:
PRINT
tabular
data.
k4:
Make
NEXT
measurement.
k&:
RESTART
prosram
and
r
L
RESTART
PLOT
DISP
PRINT
NEXT
The plots produced by the HP 85A are automatically
scaled
and
positioned
so that data takes up
the full
plotting area (see Figure 3). The vertical scale is always
calibrated in dB and the horizontal scale is calibrated
in GHz. At the bottom of the plot, the start and stop
frequencies as well as the frequency increment per di-
vision are given.
to 4 Y76
GHz
Bandrass
Filter
s
=
.
10
o
ANYNaks
s
20
f
o &
30
2
©
40
z
sa
N
60
i
«
70
—
3
4,div
Start/5tor
Freauency
(GHz)
=
Passhand
Resronsze
&
2
L4
%
h
/v'\ /\/
@
5
\/
\'_'
)
£
E
1
= =
o
{2
o
1.4
2
e
5
4
L27diw
3
Starr1/Stop
Freauency
(GHz)
Figure 3. Plotted Data.
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