Chapter 9 Smith Chart Testing
82
CellAdvisor JD720C User's Manual
501
,
1001
, and
2001
.
NOTE
Default setting is
1001
. It is recommended that you select high resolution data points
only for an instance of measuring wide frequency bands or requiring precise
measurement data.
The larger number you choose, the higher resolution you get and the longer the
instrument takes to sweep and display results. For example, selecting 501 data points
provides twice as many measurement points as 251, but it may take twice longer to
sweep and display the trace than choosing 251 data points. Changing data points
does not affect calibration status.
3
To enable the
Interference Rejection
feature, select
On
.
NOTE
Default setting is
Off
. It is recommended to use this feature only when you suspect
interfering signals in the area as it slows down measurement.
4
For JD725C and JD726C users with the option 001 Bias Tee installed.
To use the Bias Tee,
complete the following steps:
a
Select
On
for the
Bias Tee
.
b
Enter a value between
12
and
32
with 1 V step, as you desire.
NOTE
If you have set this Bias Tee to
On
, the instrument will supply a DC bias of set level
(12
– 32 V) from the
RF In
port to an active device, such as Tower Mounted Amplifier
(TMA) or Low Noise Amplifier (LNA), through the transmission line, eliminating the
need of an external power supply.
5
Tap the
Apply
button in the lower-right corner of the setup screen to save the change(s).
Performing calibration
Perform the O-S-L Calibration by pressing the
CAL
hard key. The instrument displays
on-screen instructions for you to follow through. See
“Performing Calibration” on page 33 for
more information.
Making a measurement
Once the O-S-L calibration is done, the instrument is now ready to make a measurement.
Procedure
1
Disconnect the calibration kit from the calibration point.
2
Connect an antenna or feed line to the calibration point, where is usually at the extension cable
end if used. See
for the cable connection diagram.
3
Your measurement result is displayed on the screen in real time.
CAUTION
Do not apply or connect power exc25 dBm to the
RF Out / Reflection
port. When
the input signal power is greater than +25 dBm, the input power protection is triggered to
protect the instrument and a measurement comes to stop automatically.
