VNA0440
–
VNA0440e
VNA0460
–
VNA0460e
user manual V3.1
- 18 -
7.
Calibration
•
Why calibrate
•
Calibration elements, normalization and reference plane
•
Single-port calibration procedure
•
2-port calibration procedure
•
Deembedding
Why calibrate
In vector network analysis you are interested in impedances of components and circuits.
At high frequencies almost any length of cable will act as an impedance transformer, thus
altering the impedance you actually see. Furthermore at even higher frequencies many
cables become lossy, which influences
gain
and
impedance plots.
Luckily these cables act as linear
elements and can be normalized-out' by
linear algebra. The software will do this
for you, but it should be calibrated with
some well known impedances for every
frequency of interest before you start
the actual measurement.
Therefore before using the instrument
you should perform a calibration on the
whole set-up, including the cables,
connectors, etc. for the frequency range
you want to use in your measurement.
The software stores this set of
calibration data, and since the MegiQ
VNA is very temperature stable, you will not have to perform this calibration routine very
often.
But, changing cables, connectors or frequency range means that you most renew the
calibration. Avoid bending cables too much after calibration.
Calibration and Normalization
The process of measuring the (unknown) test setup is called
Calibration
. This stores the
characteristics of the test setup.
P1
VNA
Port
calibration
here
Measure
directly
at the
port
VNA
User
calibration
here
Measure
at the end
of a coax
cable
P1
COAX
