Two-port measurements with the tracking generator
R&S FSH
1145.5973.12 4.86
E-11
Connect the DUT between the RF input and the
generator's output.
The R&S FSH displays the transmission magnitude.
Values can be read off with, for example, the markers.
The transmission calibration remains valid until the center frequency or the span is changed on the
R&S FSH. Track Gen Uncal is displayed in the top right-hand corner of the screen when calibration is
no longer valid.
If the reference is changed after calibration, greater measurement uncertainty must be anticipated. The
R&S FSH retains the calibration data but displays a red dot before Transmission in the top right-hand
corner of the screen to indicate a possible increase in measurement uncertainty (< 0.3 dB).
Changing any other of the parameters like bandwidth, detector, sweep time or measurement range has
no effect on measurement accuracy. This means they can be changed after calibration without any
reduction in accuracy.
When a data set for scalar transmission measurement is stored with calibration performed, the
calibration data can be stored along with the other settings (see Chapter 2, section "Saving Calibration
Data"). When such a data set is recalled, measurements can be performed without prior calibration,
providing the instrument's temperature does not deviate more than 5 °C from its temperature when the
data set was stored.
If the temperature deviation is greater, the R&S FSH outputs a (red) dot in front of
•
Transmission . A
precise measurement can then only be made after a calibration.
Measurement on amplifiers:
With measurements on amplifiers, the reference must be shifted so that the amplifier's transmission
function can be seen on the screen. An increase of the reference level corresponds to an increase of
the input attenuation. The R&S FSH provides a reference setting for this purpose. The position of the
0 dB reference can be shifted to positive or negative values.
Press the AMPT key.
Press the REF softkey.
Change the reference using the rotary knob or the
cursor keys, or enter a new reference via the
numeric keypad.
Confirm the entry with the ENTER key or the REF
softkey.
When performing measurements on amplifiers, make sure the R&S FSH is not overdriven. The risk of
overdriving is eliminated when the trace is within the display area on the screen (with REF POSITION =
0 dB and TRACE OFFSET = 0 dB).
The reference can also be shifted without increasing the input attenuation – for example, in order to
move the trace to the center of the screen. This is done using the REF POSITION function.
