Rohde & Schwarz 1145.1010.04/05/06, Operating Manual

Page: 129 / 813

R&S
®
ZVA/ZVB/ZVT Screen Elements
1145.1084.12 3.19 E-1
•
Inverted Smith charts are used for the display format Inverted Smith and show a vector like
polar diagrams but with grid lines of constant real and imaginary part of the admittance.
The analyzer allows arbitrary combinations of display formats and measured quantities (Trace –
Measure). Nevertheless, in order to extract useful information from the data, it is important to
select a display format which is appropriate to the analysis of a particular measured quantity;
see Measured Quantities and Display Formats.
Cartesian Diagrams
Cartesian diagrams are rectangular diagrams used to display a scalar quantity as a function of the
stimulus variable (frequency / power / time).
•
The stimulus variable appears on the horizontal axis (x-axis), scaled linearly (sweep types Lin
Frequency, Power, Time, CW Mode) or logarithmically (sweep type Log Frequency) .
•
The measured data (response values) appears on the vertical axis (y-axis). The scale of the
y-axis is linear with equidistant grid lines although the y-axis values may be obtained from the
measured data by non-linear conversions
.
The following examples show the same trace in Cartesian diagrams with linear and logarithmic x-axis
scaling.
Conversion of Complex into Real Quantities
The results to be selected in the Trace – Measure menu can be divided into two groups:
•
S-Parameters, Ratios, Wave Quantities, Impedances, Admittances, Z-Parameters and
Y-Parameters are complex.
•
Stability Factors and DC Input values (voltages, PAE) are real.
The following table shows how the response values in the different Cartesian diagrams are calculated
from the complex measurement values z = x + jy (where x, y, z are functions of the sweep variable).