Performing Measurements
R&S
®
ZND
56
Getting Started 1316.2407.02 ─ 52
6.1.2
Selecting the Sweep Range and Other Parameters
After a system preset the display shows a diagram with a dB magnitude scale, and the
S-parameter S
21
is selected as a measured quantity. This S-parameter is the forward
transmission coefficient of the DUT. It is defined as the ratio of the transmitted wave at
the DUT's output port (port no. 2) to the incident wave at the DUT's input port (port no.
1).
The R&S
ZND automatically adjusts its internal source and receiver to the selected
measured quantities: For an S
21
measurement, a stimulus signal (termed a
1
) is trans-
mitted at the analyzer port no. 1; the transmitted wave (termed b
2
) is measured at port
2. The stimulus signal from the analyzer port no. 2 is not needed except for some cali-
bration types.
By default the sweep range is set to the frequency range of the analyzer, which can be
unsuitable for your DUT. The following procedure shows you how to configure a
smaller sweep range.
1. Select STIMULUS – [START] and set the "Start Frequency" to the lowest fre-
quency you want to measure (e.g. 1.77 GHz). For convenient numeric entry, open
the "Numeric Editor" (see
Chapter 5.5.2, "Using the Numeric Editor"
Tip:
If you use the DATA ENTRY keys at the front panel for data entry, type [1][.][7]
[7] and terminate the entry with the [G/n] key.
Refer to
on page 44 to learn more about entering
numeric values and characters.
2. In the "Stop Frequency" input field, enter the highest frequency you want to mea-
sure (e.g. 2.5 GHz).
3. Select TRACE – [SCALE] > "Scale Values" and activate the "Auto Scale Trace"
function. The analyzer adjusts the scale of the diagram to fit in the entire S
21
trace,
leaving an appropriate display margin.
Tip:
Refer to
Chapter 5.6, "Scaling Diagrams"
on page 48 to learn more about the
different methods and tools for diagram scaling.
6.1.3
Calibrating the Instrument
Calibration (system error correction) is the process of eliminating systematic, reprodu-
cible errors from the measurement results. E.g., in the current test setup, the connect-
ing cables between the analyzer ports and the DUT introduce an attenuation and a
Transmission S-Parameter Measurement
