Two-port measurements with the tracking generator
R&S FSH
1145.5973.12 4.82
E-11
Two-port measurements with the tracking generator
(Only for R&S FSH with tracking generator: R&S FSH3 order No. 1145.5850.13 and 1145.5850.23,
R&S FSH6 order No. 1145.5850.26)
The R&S FSH can be supplied with an optional tracking generator to measure the transmission of two-
ports or the reflection coefficients of one-ports and two-ports. The tracking generator outputs a signal at
the current R&S FSH frequency. The nominal output level depends on the model as shown in the
following table.
Model
Tracking generator output level
Step attenuator
R&S FSH3 (1145.5850.13)
-20 dBm
-
R&S FSH3 (1145.5850.23)
-20 dBm / 0 dBm, switchable
-
R&S FSH6 (1145.5850.26)
-10 dBm ( f < 3 GHz)
-20 dBm (f > 3 GHz)
0 to 20 dB / 1 dB steps (serial
numbers 100500 and later)
Two-port transmission can be determined directly by connecting the input of the DUT to the output of
the tracking generator and the DUT’s output to the R&S FSH’s RF input. A bridge is required to
measure the reflection coefficient, e.g. the VSWR Bridge R&S FSH-Z2 (10 MHz to 3 GHz) or the
R&S FSH-Z3 (10 MHz to 6 GHz).
Due to the calibration technique used, the R&S FSH’s measurement accuracy is high for both
transmission measurements and reflection measurements. The R&S FSH offers scalar calibration
methods as standard; i.e. with transmission and reflection measurements, the magnitudes are
corrected. Vector calibration methods and measurements (option R&S FSH-K2) are possible for
increasing the dynamic range and the measurement accuracy. The operation of vector measurements
primarily differs in the expanded calibration routines.
Press the MEAS key.
Press the MEASURE softkey.
The measurement function submenu opens.
Using the cursor keys or the rotary knob, select the
TRACKING GEN menu item (highlighted in red)
and confirm your selection with the ENTER key or
the MEAS softkey.
The R&S FSH turns on the tracking generator and
switches to its softkey menu. However, the frequency
and level settings from the spectrum analyzer mode
are not changed.
The softkey menu for the tracking generator contains softkeys for calibrating transmission
measurements (TRANSM CAL) and reflection coefficient measurements (REFLECT CAL). Calibration
is necessary because the tracking generator output level does not exactly match the values specified in
the table and it is frequency-dependent. If transmission measurements are performed on a two-port, the
calibration takes the transmission characteristics of the test setup and the frequency response of the
tracking generator into account and corrects the measurement with the correction data that has been
obtained. When a reflection measurement is to be performed, during calibration the R&S FSH
measures the reflection coefficient at a short and at an open on the bridge. These two measurements
provide the correction data for reflection measurements.
