Field-Strength Measurement with Isotropic Antenna
R&S FSH
1145.5973.12 4.132
E-11
Setting the reference level:
When selecting the reference level, be sure not to overload the R&S FSH. Since the power is measured
using a resolution bandwidth that is smaller than the signal bandwidth, the R&S FSH can be overloaded
even though the trace is within the measurement diagram. To prevent overload from occurring, the
signal can be measured using the largest possible resolution bandwidth and the peak detector. When
this setting is used, the trace must not exceed the reference level.
To simplify operation and the prevent measurement errors, the R&S FSH offers an automatic routine for
setting the reference level
Press the LEVEL ADJUST softkey.
The R&S FSH will start the measurement of the
optimum reference level using a resolution bandwidth
of 1 MHz, a video bandwidth of 1 MHz and the peak
detector. During the measurement, it displays the
message "Please wait. Setting level for channel power
measurement."
It will then set the optimum reference level.
Setting the channel bandwidth:
The channel bandwidth is used to define the bandwidth in which the R&S FSH calculates the resultant
field strength around the center frequency that has been set.
Press the CHAN BW softkey.
The R&S FSH will open the entry field showing the
channel bandwidth that is currently set.
Enter a new channel bandwidth by using the
numeric keys and confirm the entry with the unit you
want, or
Change the channel bandwidth by using the rotary
knob or the cursor keys and confirm the entry with
the ENTER key or the CHANNEL BW softkey.
The R&S FSH will automatically adapt the span to the
entered channel bandwidth (span = 1.2 x channel
bandwidth) so that the channel power will be measured
correctly.
The minimum bandwidth that can be set is 8.33 kHz
with R&S
FSH3 models 1145.5850.03 and
1145.5850.13.
If you set a smaller bandwidth, the R&S FSH will set a
frequency of 8.33 kHz and output the message "Range
exceeded".
In the case of R&S FSH3 model 1145.5850.23 and the
R&S FSH6, the minimum channel bandwidth is 833 Hz
at a span of 1 kHz.
