Line Loss And Velocity Factor - Keysight N9923A User Manual

Time Domain – Option 010
Time Domain (Transform) Settings
Network Analyzer Windows Frequency Span and TDR Window
Selection for Step Rise Time (Approximated)
The following table shows the approximated relationship between the
frequency span and the window selection for impulse width and step rise time.
Refer to
Window
Minimum
Medium
Maximum
Figure 4-1 Network Analyzer TDR Rise Time

Line Loss and Velocity Factor

By default, the FieldFox does NOT correct Time Domain measurements to
account for the inherent loss of a cable. However, to make more accurate
measurements, Line Loss and Velocity Factor should be considered.
About Velocity Factor and Line Loss
— Velocity Factor is a property of the physical material of a cable. A VF of 1.0
— Line Loss is specified in dB/m (or ft). In addition to the length of the cable,
The following is an example showing how Line Loss works:
Keysight N9923-90001 User's Guide
Figure 4-1 on page
Low-pass step
(10% to 90%)
0.45/ f span
0.99 / f span
1.48 / f span
corresponds to the speed of light in a vacuum, or the fastest VF possible. A
polyethylene dielectric cable has VF = 0.66 and a cable with PTFE dielectric
has VF = 0.7.
loss is also directly proportional to the frequency of the signal that passes
through the cable.
69.
Low-pass impulse
0.60 / f span
0.98 / f span
1.39 / f span
Bandpass impulse
1.20 / f span
1.95 / f span
2.77 / f span
69