R&S
®
ZVL System Overview
Basic Concepts
Quick Start Guide 1303.6538.62-01 83
E The magnitude of the reflection coefficient of a short circuit (Z = 0, U = 0) is one, its
phase is –180
0
.
3.1.7.4 Smith Chart
The Smith chart is a circular diagram that maps the complex reflection coefficients S
ii
to normalized impedance values. In contrast to the polar diagram, the scaling of the
diagram is not linear. The grid lines correspond to points of constant resistance and
reactance.
E Points with the same resistance are located on circles.
E Points with the same reactance produce arcs.
The following example shows a Smith chart with a marker used to display the stimulus
value, the complex impedance Z = R + j X 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.
Smith chart construction
In a Smith chart, the impedance plane is reshaped so that the area with positive
resistance is mapped into a unit circle.
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