Common Measurement Settings
R&S
®
FSW
412
User Manual 1173.9411.02 ─ 43
+ 10 mA is obtained for a short circuit at the output of the voltage divider. In order to
use biasing it is not important to know the exact current flowing through the diode since
the conversion loss must be set to a minimum with the frequency. Therefore, it makes
no difference whether the setting is performed by an open-circuit voltage or by a short-
circuit current. A DC return path is ensured via the 66
Ω
resistor, which is an advant-
age in some mixers.
Conversion Loss Tables
Conversion loss tables consist of value pairs that describe the correction values for
conversion loss at certain frequencies. Correction values for frequencies between the
reference values are obtained by interpolation. Linear interpolation is performed if the
table contains only two values. If it contains more than two reference values, spline
interpolation is carried out. Outside the frequency range covered by the table the con-
version loss is assumed to be the same as that for the first and last reference value
(see
).
Figure 8-16: Conversion loss outside the band's frequency range
Predefined conversion loss tables are often provided with the external mixer and can
be imported to the R&S
FSW.
Alternatively, you can define your own conversion loss tables. Conversion loss tables
are configured and managed in the "Conversion loss Table Settings" tab of the "Exter-
nal Mixer Configuration" dialog box.
See
"Managing Conversion Loss Tables"
on page 425 for more information about con-
version loss tables.
When using external mixers with optional bandwidth extensions larger than 512
MHz,
special conversion loss tables are required, see
"External Mixers and Large Bandwidth
Data Input and Output
