Kroks ARINST VNA-PR1, Руководство пользователя

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2-port vector network analyzer ARINST VNA-PR1
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Figure 9.11 - Smith chart after calibration
9.6.3. Connect an additional (adapter) cable of short length with a total signal attenuation of no more
than 1 dB. In this case, in the chart, a circle with a minimum radius is transformed into an arc (Figure
9.12).
Figure 9.12 - Offset of the calibration plane by an additional cable
This is due to the fact that the additional cable has a phase attack proportional to the length of the ca-
ble. To compensate for this phenomenon, you need to set an approximate delay value in picoseconds in
the device options.
Formula for calculating the compensation of the time T of propagation of the probing signal along the
additional cable:
where L
– cable length, (m)
С – the speed of light, (m / s)
VF
– the velocity factor, has a value of <1
To convert the T value into picoseconds (ps), the resulting value must be multiplied by 10
12
.
9.6.4. Enter the numerical value of the compensation time (T) in picoseconds, calculated by the formu-
la in the field Electrical delay .
Use the buttons and to adjust the exact compensation time at which the graph on the chart
will be drawn into a circle with a minimum radius (Figure 9.13).
Back button-exit to the main menu.