Cable and Antenna Test Mode
R&S
®
Cable Rider ZPH
129
User Manual 1321.0950.02 ─ 07
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Smith Chart
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Phase Measurement
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Calibrating Measurements
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7.1.1
Reflection Measurements
The reflection measurement (S11) is a good way to get an idea if the transmission sys-
tem works properly. If unusual amounts of signal power are being reflected, you can
guess that there is something wrong in the system.
A reference signal is transmitted along the transmission system, and this signal is
reflected back by a discontinuity along the transmission line, usually by an impedance
mismatch. This reflected signal is measured and compared with the reference signal to
determine the loss of power.
The reflection measurement can be performed in the following measurement formats:
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Magnitude (return loss in dB)
Return loss is power loss in dB, measured over the specified frequency range of
the transmission system. The return loss is the default measurement mode in R&S
Cable Rider ZPH.
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SWR
The standing wave ratio, SWR provides the ratio of the maximum and minimum AC
voltages along the transmission line caused by the reflections.
1. Press the [MEAS] key
2. Select the "SWR" or "Return Loss" softkey.
The R&S Cable Rider ZPH starts the reflection measurement over its entire fre-
quency range with the selected measurement format.
Figure 7-3
shows an example of a reflection measurement in magnitude and SWR for-
mat without any major faults in the cable or the antenna.
Figure 7-3: Reflection measurement
You can perform reflection measurements on the complete system or on individual
components of the system. If you measure while two or more system components are
connected, the results of the reflection measurement are an aggregate over these
components. Therefore you can only see the aggregated magnitude of the reflected
power in a specified frequency range.
Performing Cable and Antenna Measurements
