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Making Measurements
Measuring Reflection Response
View
and
Interpret
the
Reflection
Measurement
Results
1. To view the entire measurement trace on the display, press
@ZiE]
Autoscale.
2. To interpret the reflection measurement, refer to Figure 3-10 or
your analyzer’s display if you are making this measurement on your
instrument.
a. The values shown on the horizontal axis are the frequencies in MHz.
The values shown on the vertical axis are the power ratios in decibels
(dB)
of the reflected signal divided by the incident power. ‘lb display
the result in logarithmic magnitude format (designated by Log Mag
at the top of the measurement screen), the analyzer computes the
measurement trace using the following formula:
Reflection
(dB)
= 10 log
where
Pres
= the power of the signal reflected from the device and
where
Pin=
= the incident power.
b. A level of 0
dB
indicates that all of the power applied to the DUT
is reflected back, and that none of it passes through the DUT or is
absorbed by the DUT.
c. Values less than 0
dB
indicate that power is either absorbed or
transmitted by the DUT. Although they are not typically seen, values
greater than 0
dB
do occur under certain circumstances such as when
the measurement needs to be enhanced by calibration, or when the
device is active (an amplifier for instance) and perhaps oscillating.
3-28
深圳市盛腾仪器仪表有限公司 Tel:0755-83589391 Fax:0755-83539691 Website: www.Sengt.com
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