Improving level performance
R&S
®
SMA100B
213User Manual 1178.3834.02 ─ 09
8 Improving level performance
To adjust the RF output signal to specific needs in your application, the R&S SMA100B
offers different functions:
●
Attenuator
The R&S SMA100B 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 213.
●
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 216.
●
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 221.
●
Power sensors
The R&S SMA100B 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 8.4, "Using power sensors", on page 233
8.1 Attenuator
About the attenuator
The step attenuator is either an electronic or a mechanical device. Instruments with fre-
quency options up to 20 GHz use an electronic step attenuator, providing fast and wear
free level settings. Instruments capable to generate higher frequency signals use
mechanical step attenuators. Depending on the frequency range and the installed high-
power option, both types of step attenuators can be built in, and you can select the
type to be used below 20 GHz.
To achieve a consistent level setting behavior for all frequencies, the mechanical step
attenuator is used even for lower frequencies while the electronic one is disregarded.
Especially in frequency ramp sweep mode, which requires a consistent level adjust-
ment behavior, the R&S SMA100B automatically activates the mechanical step attenu-
ator and disables the selection of the electronic step attenuator.
Attenuator
To Next Page
Loading...
