Keysight Technologies C Series - Velocity Factor

Keysight N9915-90020 User’s Guide 109
NA (Network Analyzer) Mode
NA Mode Settings
— Electrical delay applies to a specific trace
— Port extensions apply to specific hardware ports
Port Extensions and Electrical Delay can be set independently. When both are
set, the delay adds together. Learn more about Electrical Delay in
“Electrical
Delay” on page 101
.
How to apply Port Extensions
1. Press Meas Setup 4
> Port Extensions > Port Extensions ON > Port1
Extension
2. Then enter time value using the numeric keypad, the arrows, or the
rotary knob. Press
Enter or select a seconds (time) multiplier.
You can also set Port Extensions by pressing Meas Setup 4 then Calibration
(settings).
While setting Port Extension, the physical length of the extension, at the
current Velocity Factor setting, is visible to the right (red box in above
image).
Velocity Factor
The electrical delay or port extension value is entered as delay, or electrical
length, in units of time.
Entering the velocity factor causes the FieldFox to accurately display the
equivalent physical length in meters (NOT available in feet) that corresponds
to the entered electrical delay.
Velocity factor is the ratio of the velocity of wave propagation in a coaxial cable
to the velocity of wave propagation in free space. This velocity depends on the
relative permittivity of the cable dielectric (er).
Velocity factor = 1/sqrt(er)
VF = 0.66 corresponds to wave propagation through a polyethylene dielectric.
VF = 1.0 (default setting) corresponds to wave propagation through free space
(a vacuum).
How to set Velocity Factor
1. Press Meas Setup 4 > Port Extensions > Velocity Factor
2. Then enter a value between 0.1 and 1 using the numeric keypad, then
press Enter.