Specifications

Setting and Using the Measurement Functions R&S FSH
1145.5973.12 4.100 E-10
One-Port Measurement of Cable Loss
(Available ony if the option R&S FSH-K2 is installed.)
When measuring return loss at the end of short-circuited or open-circuit cables, cable loss can be
calculated on the basis of the following aspect: A short circuit or an open circuit at the end of the cable
completely reflects the traversing wave. Since the wave traverses the cable twice, the returning wave at
the measurement port of the bridge is attenuated by twice the amount of the cable loss. The level ratio
of the received signal to the one fed to the cable is thus the same as twice the loss of the measured
cable.
If the option R&S FSH-K2 is installed, the R&S FSH enables users to measure cable loss directly in
accordance with the methods for return loss measurement without having to convert return loss to cable
loss.
Operation:
¾ Connect the R&S FSH-Z2 bridge to the R&S FSH.
¾ Activate the TRACKING GEN mode on the R&S FSH (MEAS key, MEASURE: TRACKING GEN
softkey).
¾ Set the required frequency range on the R&S FSH.
¾ Switch on vector measurement (MEAS key, MEAS MODE softkey, VECTOR menu item).
¾ Calibrate the R&S FSH (MEAS key, RELECT CAL softkey).
¾ Connect the cable to be measured to the measurement port of the bridge. The other end of the cable
must be terminated with a short circuit or left open.
The R&S FSH shows the return loss of the cable.
¾ Press the MEAS MODE softkey.
¾ Using the rotary knob or the cursor keys, select
CABLE LOSS from the menu.
¾ Confirm the selection with the ENTER key or the
MEAS MODE softkey.
The R&S FSH will now display the measured cable
loss in dB.
The R&S FSH calculates the cable loss from the average of the maximum and minimum values of the
displayed trace. Thus, the cable loss is an average value within the displayed frequency range.
Loss at specific frequencies can be determined with one or more markers.