% Author: Prof. Dr. Matthias Jung, DL9MJ
% Year: 2026
\begin{circuitikz}
    \draw[-Triangle](0,0) -- (5.0,0.0) 
        node[anchor=north east] () {$f$};
    \draw[-Triangle](0.0,0.0) -- (0.0,3.0)
        node[anchor=north east] () {$|Z|$};

    \draw[very thick, DARCblue]
        (2.10,3.00)
        .. controls (2.5,0.0) and (2.5,0.0) .. (2.90,3.00)
        coordinate[pos=0.5] (min);

    \draw[gray, dashed] (min) -- (min -| 0,0) coordinate (x1);
    \draw[gray, dashed] (min) -- (min |- 0,0) coordinate (x2);

    \draw(x2) node[anchor=north] {$f_0$};
    \draw(x1) node[anchor=east] {$R$};

\end{circuitikz}