R&S
®
ZVL System Overview
Basic Concepts
Quick Start Guide 1303.6538.62-01 85
Circles of equal
resistance
Arcs of equal
reactance
Open-circuited
load (Z = infinity)
Short-circuited
load (Z = 0)
Matching
impedance (Z = Z
0
)
Examples for special points in the Smith chart:
E The magnitude of the reflection coefficient of an open circuit (Z = infinity, I = 0) is
one, its phase is zero.
E The magnitude of the reflection coefficient of a short circuit (Z = 0, U = 0) is one, its
phase is –180
0
.
3.1.7.5 Inverted Smith Chart
The inverted Smith chart is a circular diagram that maps the complex reflection
coefficients S
ii
to normalized admittance values. In contrast to the polar diagram, the
scaling of the diagram is not linear. The grid lines correspond to points of constant
conductance and susceptance.
E Points with the same conductance are located on circles.
E Points with the same susceptance produce arcs.
The following example shows an inverted Smith chart with a marker used to display the
stimulus value, the complex admittance Y = G + j B and the equivalent inductance L
(see marker format description in the help system).
Polar diagram types
A comparison of the Smith chart, the inverted Smith chart and the polar diagram
reveals many similarities between the two representations. In fact the shape of a trace
does not change at all if the display format is switched from Polar to Smith or Inverted
Smith – the analyzer simply replaces the underlying grid and the default marker
format.
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