7- 35
Operating Concepts
Electrical Delay
Electrical Delay
The softkey adjusts the electrical delay to balance the phase of the test device.
This softkey must be used in conjunction with or (with
cut-off frequency) in order to identify which type of transmission line the delay is being added to. These
softkeys can be accessed by pressing the
key.
Electrical delay simulates a variable length lossless transmission line, which can be added to or removed
from a receiver input to compensate for interconnecting cables, etc. This function is similar to the
mechanical or analog "line stretchers" of other network analyzers. Delay is annotated in units of time with
secondary labeling in distance for the current velocity factor.
With this feature, and with (refer to “Setting the Electrical Delay” on page 1-38),
an equivalent length of air-filled, lossless transmission line is added or subtracted according to the following
formula:
Once the linear portion of the test device's phase has been removed, the equivalent length of the lossless,
transmission line can be read out in the active marker area. If the average relative permittivity (
r
) of the test
device is known over the frequency span, the length calculation can be adjusted to indicate the actual
length of the test device more closely. This can be done by entering the relative velocity factor for the test
device using the calibrate more menu. The relative velocity factor for a given dielectric can be calculated by:
assuming a relative permeability of 1.
Length meters
Freq MHz1.20083
----------------------------------------------------------------=
Velocity Factor
1
r
--------=
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