System Overview
R&S
®
ZVA
71
Quick Start Guide 1145.1090.62 ─ 10
3.2.4.5
Inverted Smith Chart
The inverted Smith chart is a circular diagram that maps the complex reflection coeffi-
cients 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.
●
Points with the same conductance are located on circles.
●
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.
A comparison of the inverted Smith chart with the Smith chart and the polar diagram
reveals many similarities between the different representations. In fact the shape of a
trace does not change at all if the display format is switched from "Polar" to "Inverted
Smith" or "Smith" – the analyzer simply replaces the underlying grid and the default
marker format.
Inverted Smith chart construction
The inverted Smith chart is point-symmetric to the Smith chart:
The basic properties of the inverted Smith chart follow from this construction:
●
The central horizontal axis corresponds to zero susceptance (real admittance). The
center of the diagram represents Y/Y
0
= 1, where Y
0
is the reference admittance of
Screen Elements
