Figure

2003/5 平野拓一（東京工業大学）
Takuichi Hirano (Tokyo Institute of Technology)

Dipole

h = 3;
a = h/100;
i0 = 0.5;
λ0 = 1;
k0 = ((2*π)/λ)0;
cur[z_] := i0*Sin[k0*(h - Abs[z])];
Do[
ParametricPlot[{cur[z], z}, {z, -h, 
          h}, 
AspectRatio -> 
          GoldenRatio, 
Prolog -> {Line[{{-a/
                    2, -h}, {a/2, -h}, {a/2, h}, {-a/2, 
                  h}, {-a/
                    2, -h}}]}, 
PlotRange -> {{-i0, i0}, {-h, 
              h}}, 
PlotStyle -> {AbsoluteThickness[
              2], RGBColor[1, 0, 0]}, 
Axes -> 
          None]
, {h, λ0/16, 
        3*λ0, λ0/16}
]