I'm trying to plot a smithchart, which has negative impedances, too. This is how far i got till now:
\documentclass[]{standalone}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{pgfplots.smithchart}
\makeatletter
\begin{document}
\begin{tikzpicture}
\begin{smithchart}[
yticklabel around circle,
show origin,
xtick={-0.3,-0.2,-0.1,0.1,0.2,0.3,0.4,0.5,1,1.5,2,3,4,5,10,20,-20,-10,-5,-4,-3},
]
\addplot[mark=none,line width=2]
coordinates{
(1, 0) (1, 0.1) (1,0.2) (1,0.3) (1,0.4) (1,0.5) (1,0.5)
};
\end{smithchart}
\end{tikzpicture}
\end{document}
The result is not very pleasant, the circles of the y-axis just stop, when the x-values start to get negative:
The goal would be a look similar to this, but I would be happy, if the y-axis would be continued :)
EDIT: So I made same progess. first, I could move the outer circle labeling the x-axis:
\documentclass[preview]{standalone}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{pgfplots.smithchart}
\makeatletter
\begin{document}
\begin{tikzpicture}
\begin{smithchart}[
yticklabel around circle,
show origin,
xtick={-0.3,-0.2,-0.1,0.1,0.2,0.3,0.4,0.5,1,1.5,2,3,4,5,10,20,-20,-10,-5,-4,-3},
xmin=-0.3, %works quite well
xmax=-3, %xmax seems to be always infinty?!?!?
ticklabel style={opacity=0.5},
]
\addplot[mark=none,line width=2]
coordinates{
(1, 0) (1, 0.1) (1,0.2) (1,0.3) (1,0.4) (1,0.5) (1,0.5)
};
\end{smithchart}
\end{tikzpicture}
\end{document}
The result looks like this, which is not quite satisfying, as xmax is ignored (always near infinty) and drwing lines is just possible inside the old, small (positive-x) circle:
And the next thing, drawing y-circles when x is negative, seems also to be possible in some way.
...... %just as before
\begin{smithchart}[
yticklabel around circle,
show origin,
xtick={-0.3,-0.2,-0.1,0.1,0.2,0.3,0.4,0.5,1,1.5,2,3,4,5,10,20,-20,-10,-5,-4,-3},
ygrid each nth passes x={-3},
ticklabel style={opacity=0.5},
]
\addplot[mark=none,line width=2]
coordinates{
(1, 0) (1, 0.1) (1,0.2) (1,0.3) (1,0.4) (1,0.5) (1,0.5)
};
\end{smithchart}
.....
And the result:
EDIT again: By overlaying two smith charts, it comes again a bit closer to the desired look... But one can't draw lines, where x is negative!
\documentclass[preview]{standalone}
\usepackage{tikz}
\usepackage{pgfplots}
\usetikzlibrary{pgfplots.smithchart}
\makeatletter
\begin{document}
\begin{tikzpicture}
\begin{smithchart}[
show origin,
xtick={-0.3,-0.2,-0.1,0.1,0.2,0.3,0.4,0.5,1,1.5,2,3,4,5,10,20,-20,-10,-5,-4,-3},
ygrid stop at x={0.2:-.3,-0.2:-.3, 0.5:-.3,-0.5:-.3, 1:-.3,-1:-.3, 2:-3,-2:-2.99, 5:-6,-5:-5.99,},
xmin=-0.3, %works quite well
%xmax=-3, %xmax seems to be alwys infinty?!?!?
ticklabel style={white,opacity=0},
]
\end{smithchart}
\begin{smithchart}[
show origin,
xtick={-0.3,-0.2,-0.1,0.1,0.2,0.3,0.4,0.5,1,1.5,2,3,4,5,10,20,-20,-10,-5,-4,-3},
ygrid stop at x={0.2:-3,-0.2:-3,0.5:-3,-0.5:-3,1:-3,-1:-3, 2:-3.01,-2:-3.0, 5:-6.01,-5:-6.0,},
xmin=-0.3, %works quite well
%xmax=-3, %xmax seems to be alwys infinty?!?!?
ticklabel style={opacity=0},
]
\addplot[mark=none,line width=2]
coordinates{
(1, 0) (1, 0.1) (1,0.2) (1,0.3) (1,0.4) (1,0.5) (1,0.5)
};
\addplot[mark=none,line width=0.5]
coordinates{
(1, 0) (-0.3, 0) % this one is not drawn outside!!!
};
\end{smithchart}
\end{tikzpicture}
\end{document}