Agilent Technologies ENA Series User Manual page 193

Measurement range
In the time domain function, the measurement range means the range within which the
response can be measured without repetition. The repetition of the response occurs because
measurement in frequency domain is performed discretely instead of continuously. The
measurement range is inversely proportional to the frequency difference between adjacent
measurement points. The frequency difference between measurement points
expressed as follows using the span of the sweep frequency
N
meas
Therefore, the measurement range is proportional to (the number of points- 1) and
inversely proportional to the span of the sweep range. To enlarge the measurement range,
use one of the following methods:
• Increase the number of points.
• Narrow the span of the sweep range.
NOTE When you change the above settings after performing calibration, you need to perform
calibration again.
The sweep range is expressed as time or distance. The time of the measurement range
is as follows:
The distance of the measurement range
factor
NOTE The maximum length of the DUT that can be measured in the transmission measurement is
L
span
returns, it is 1/2 of
The velocity factor varies depending on the material through which the signal propagates.
For polyethylene, it is 0.66; for Teflon, 0.7.
The change of the setting and the change of the response
Table 8-1 shows the effect of the change of the measurement conditions on the response
resolution and the measurement range.
Table 8-4 Effect of setting changes
Change of setting
Widen the sweep range.
Sets the window type to maximum.
Increase the number of points.
8
.
and the speed of light in a vacuum (3´10
V
. On the other hand, in the reflection measurement, because the signal goes and
.
L
span
Response resolution
Becomes smaller.
Becomes larger.
Does not change.
Analysis in Time Domain (Option 010)
Transformation to time domain
and the number of points
F
span
F
span
DF = -----------------------
N – 1
meas
1
T = ------ -
span
DF
is expressed as follows using the velocity
L
span
8
m/s).
c
Vc
L = ------ -
span
DF
Measurement range
Becomes narrower.
Does not change.
Becomes wider.
DF is
T
span
Sidelobe
Does not change.
Becomes lower.
Does not change.
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