% Author: Prof. Dr. Matthias Jung, DL9MJ
% Year: 2026
\begin{tikzpicture}
    \pgfplotsset{samples=200}
    \begin{axis}[
        ymin = 0,
        ymax = 1.1,
        xmin = 0.05,
        xmax = 20,
        xmode = log,
        log ticks with fixed point,
        domain = 0.05:20,
        grid=both,
        xlabel = {$\frac{R_\mathrm{L}}{R_\mathrm{i}}$},
        ylabel = {$\frac{P_\mathrm{L}}{P_\mathrm{max}}$},
        thick,
        smooth,
        no markers
    ]
    \addplot+[name path=A,ultra thick, DARCblue] { 
        (4*x)/((1+x)^2)
    };
    \end{axis}
\end{tikzpicture}