% Author: Prof. Dr. Matthias Jung, DL9MJ
% Year: 2024
\begin{circuitikz}
    \draw(0,0) coordinate(start)
        to [stroke diode, v^={$U_\text{d}$}, i_={$I_\text{d}$}] ++(3,0)
        to [european resistor, v={$U_\text{k}$}] ++(0,-2)
        to [short] ++(-3,0) coordinate(end);
    \draw(start)
        to [battery2, v^={$U_\text{a}$}] (end);
\end{circuitikz}