User`s guide
4. Adjust the spectrum analyzer for measurement conditions or settings. Turn on the tracking
generator and set the amplitude level by pressing
(AUX],
Track Gen , and setting
SRC PWR ON OFF to ON. Set center frequency, span, and other settings.
5. Replace the DUT with a short circuit
6. Normalize the trace by performing the following functions:
a. Press
[ml,
select B using TRACE A B C , then CLEAR WRITE B to display the
reference trace in B.
b. Press BLANK B to store the reference trace in B.
c.
Press More 1 of 3 , then set NORMLIZE ON OFF to ON to activate the trace A minus
trace B function, and display the results in trace A for each sweep. The normalized trace
or flat line represents 0
dB
return loss.
Measuring the Return Loss
Note
If possible, use a coupler or bridge with the correct test port connector for
both calibrating and measuring. Any adapter between the test port and DUT
degrades coupler/bridge directivity and system source match. Ideally, you
should use the same adapter for the calibration and the measurement. Be sure
to terminate the second port of a two-port device.
7. After calibrating the system with the above procedure, reconnect the filter in place of the
short circuit without changing any spectrum analyzer settings.
8. Use the marker to read return loss. Press
m
and position the marker with the knob to
read the return loss at that frequency (see Figure 4-16).
&
REF
.B
d8m
MKR 324.27 IHz
fsTTEN
10
dB
-26.45
dB
.;..
.,y'
"',
Y----L.
MARKER
'-
Y,&ik"y
:
:
1'4.27
MHz
MARKER
DELTA
DL
'Iii.45
dB
. . . . . . . . .
..~........,,,~~,,,,,,,,,,,,,,...,,,..,,,
;I:
ON
E
.,.
MKNOISE
ON
x
W*-SB
:
SC FC
CoRR
.
..~~~~~~~~~....~.~~~~~~~~~~~.........~~~.,.,,,,,,,,.........~,,,,,,,,,,,,,,.,,,,,,,,,,,,,....,,,,,
MARKERS
OFF
I: : I
I
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.._..
. . . . . . . . . . . . .
..___.
___...___
I
CENTER 322.50 MHz
1
Y":
SPAN 37.24 MHz
RES
BW
308 kHz UBW 1EE kHz
SWP
28
M5eC
RT
Figure 4-16. Measuring the Return Loss of the Filter
4-18 Making Measurements