Rohde & Schwarz R&S SMB100B - Attenuator; Improving Level Performance

Improving level performance
R&S
®
SMB100B
151User Manual 1178.3711.02 ─ 08
7 Improving level performance
To adjust the RF output signal to specific needs in your application, the R&S SMB100B
offers different functions:
●
Attenuator
The R&S SMB100B is equipped with a step attenuator that enables you to vary the
amplitude of the RF signal in a wide range. It is characterized by low VSWR (volt-
age standing wave ratio) over the full level and frequency range, and provides
highest level accuracy and noise suppression.
See "About the attenuator" on page 151.
●
Automatic Level Control (ALC)
The automatic level control system provides stable RF signals with highest abso-
lute level accuracy over temperature and time.
See "About ALC" on page 154.
●
User correction (UCOR)
The user correction function allows you to compensate frequency responses of
external setups (e.g. losses of cables) and achieve a stable input signal over fre-
quency directly at the DUT.
See "About UCOR" on page 156.
●
Power sensors
The R&S SMB100B has excellent absolute level accuracy. Since a DUT is rarely
connected directly to the generator, but with cables or other components, the refer-
ence level shifts from the RF output to the DUT. To calibrate this level with high
accuracy, i.e. in the tenth dB range, you can connect an R&S NRP power sensor to
the generator. The power sensor transmits its readings to the generator, which indi-
cates these measurement results in the display. Thus you can adjust the RF output
power of the generator until you reach the target level at the DUT.
See Chapter 7.4, "Using power sensors", on page 168
7.1 Attenuator
About the attenuator
The step attenuator is an electronic device without mechanical components, providing
fast and wear free level settings.
According to the requirements of your application, you can select different attenuator
characteristics.
The following are examples of test requirements and the corresponding configuration:
●
Automatic configuration
Select standard operation mode ("Auto"), in which the generator adjusts the attenu-
ation of the RF output signal automatically.
●
DUT tests under low signal to noise conditions
Low output power is suitable to test the behavior of a DUT under low signal to
noise conditions.
Attenuator