% Author: Dr. Matthias Jung, DL9MJ
% Year: 2020
\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 [thick, DARCblue] plot [rounded corners=10mm] coordinates {
        (1.20,0.05)
        (2.25,0.60)
        (2.50,3.00)
        (2.75,0.60)
        (3.75,0.05)
    };
\end{circuitikz}