R&S ZVB - Page 57

R&S
®
ZVA / R&S
®
ZVB / R&S
®
ZVT System Overview
Screen Elements
Operating Manual 1145.1084.12 – 30 42
in order to deduce the following properties of the graphical representation in an inverted Smith chart:
 Real reflection coefficients are mapped to real admittances (conductances).
 The center of the Γ plane (Γ = 0) is mapped to the reference admittance Y
0
, whereas the circle
with |Γ| = 1 is mapped to the imaginary axis of the Y plane.
 The circles for the points of equal conductance are centered on the real axis and intersect at Y =
infinity. The arcs for the points of equal susceptance also belong to circles intersecting at Y =
infinity (short circuit point (–1,0)), centered on a straight vertical line.
Examples for special points in the inverted Smith chart:
 The magnitude of the reflection coefficient of a short circuit (Y = infinity, U = 0) is one, its phase is
–180
0
.
 The magnitude of the reflection coefficient of an open circuit (Y = 0, I = 0) is one, its phase is zero.
Measured Quantities and Display Formats
The analyzer allows any combination of a display format and a measured quantity. The following rules can
help to avoid inappropriate formats and find the format that is ideally suited to the measurement task.
 All formats are suitable for the analysis of reflection coefficients S
ii
. The formats SWR, Smith and
Inverted Smith lose their original meaning (standing wave ratio, normalized impedance or
admittance) if they are used for transmission S-parameters, Ratios and other quantities.
 The complex Impedances, Admittances, Z-parameters, and Y-parameters are generally displayed
in one of the Cartesian diagrams with linear vertical axis scale or in a polar diagram.
 The real Stability Factors, DC Inputs, and the PAE is generally displayed in a linear Cartesian
diagram (Lin Mag or Real). In complex formats, real numbers represent complex numbers with
zero imaginary part.
The following table gives an overview of recommended display formats.
Complex dimensionless
quantities:
S-parameters and ratios
Complex quantities with dimensions:
Wave quantities, Z-parameters, Y-parameters,
impedances, admittances
Real quantities:
Stability Factors, DC
Input 1/2, PAE
Lin Mag
(default for Z-parameters, Y-parameters,
impedances, admittances)
(default)
dB Mag
(default)
(default for wave quantities)
–
Phase
–