% Author: Dr. Matthias Jung, DL9MJ
% Year: 2021
\begin{tikzpicture}
   \draw plot[
          variable=\t,
          domain=0:360,
          smooth,samples=51
      ] 
    ({20*sin(\t)}:{6*pow(0.95*sin(\t/2),5)});
  
   \draw plot[
          variable=\t,
          domain=0:360,
          smooth,samples=51
      ] 
    ({180+30*sin(\t)}:{0.8*pow(sin(\t/2),5)});

  \draw[very thick] (0,-0.5) -- (0,0.5);

  \draw(-1.5,0) node[] (A) {a};
  \draw( 5.5,0) node[] (B) {b};
  
  \draw[{Triangle}-{Triangle}] (A.east)  -- (B.west);

\end{tikzpicture}