VNA0440
–
VNA0440e
VNA0460
–
VNA0460e
user manual V3.1
- 25 -
Open
1.
Connect both ports to the
Open
terminations.
2.
Select
P1-Open / P2-Open
and press
Calibrate
.
Short
3.
Connect both ports to the
Short
terminations.
4.
Select
P1-Short / P2-Short
and
press
Calibrate
.
Load
5.
Connect both ports to the
Load
terminations.
6.
Select
P1-Load / P2-Load
and
press
Calibrate
.
This will also calibrate the
isolation.
Through
7.
Connect the two ports together with the
Through
calibration connector.
8.
Select
P2-Tru-P1
and
press
Calibrate
.
Final check
With the two ports still connected together, press
Sweep
. In both Smith Charts the
measurement points should be close to the center
and the return losses lower than -40dB. The
Through gain should be near zero.
You are ready to measure now, but remember,
after changing cables, connectors or frequency
range you'll have to renew the calibration.
De-embedding
It is important that the reference plane is as close as possible to the point where the
impedance must be measured, for example at the base of an antenna. Depending on the
frequency even a few millimeters distance can change the phase and give misleading
results.
If it is not possible to calibrate close to the measuring point, the last piece of trace or
transmission line can be de-embedded from the measurement.
For a PCB based UFL measurement the following procedure can be used to de-embed a
trace. For connector measurements a similar procedure can be used.
•
Calibrate the cables etc with the VNA Sandbox OSL terminations.
•
On the DUT, open the circuit where the desired measuring point is located: remove
components or cut the trace at that point.
