documentclass[tikz, border=1cm]{standalone}
usepackage{ pgfplots}
usetikzlibrary{decorations.text, decorations.markings}
usetikzlibrary{intersections}
usetikzlibrary{arrows}

pgfplotsset{
    every axis label/.append style={font=small},
    compat=newest,
}


begin{document}
  begin{tikzpicture}[xscale=1,yscale=1]
  pgfmathsetmacro{ea}{1.5}
  pgfmathsetmacro{eb}{1}
  draw[red, samples=200, smooth] plot[id=curve, raw gnuplot] function{
    f(x,y) = (0.3 + ((ea-eb)/(ea+2*eb))/(x**2 + y**2))*y ;
    set xrange [-4:4];
    set yrange [-2:2];
    set view 0,0;
    set isosample 1000,1000;
    set cntrparam levels 50;
    set cont base;
    unset surface;
    splot f(x,y)
  } ;
  fill[gray!50, draw=blue, thick] (0,0) circle (1.01);

  clip (0,0) circle (1);
  foreach i in {-0.9,-0.675,...,1} {
  draw[red, decoration={
      markings,
      mark=at position 0.5 with {arrow{latex'}}}, postaction={decorate}] (-1,i) --  (1,i);
  }
  end{tikzpicture}
end{document}