% Author: Dr. Matthias Jung, DL9MJ
% Year: 2022
\begin{tikzpicture}
  \draw [very thick] (0,4) -- ++(5,0) ++(0.5,0) node[](){1};
  \draw [very thick] (2.25,1.5)
    to [short,o-] ++(-1.5,0)
    arc(90:-90:-0.15) coordinate(c1);
  \draw [very thick] (2.75,1.5)
    to [short,o-] ++(+1.5,0)
    arc(-90:90:0.15) coordinate(c2);
  \draw [very thick](c1) -- (c2);
  \draw (c2) ++ (0.5,-0.15) node[](){2};
  \draw [very thick] (0.75,0) -- ++(3.5,0) ++(0.5,0) node[](){3};
\end{tikzpicture}