<< Algebra`ReIm`
ClearAll[zrej];
zrej[x_] := x /: Im[x] = 0;
realne = {γ, ϵ0, ω, ϵrr, ϵri, Ecko, μ, tgδ};
zrej /@ realne;
ϵ = ϵ0*(ϵrr - 
              I*ϵri);
pstr = Re[Ecko*Conjugate[Ecko*I*ω*ϵ]]

lambdakvadrat = 
      I*ω*γ*μ - (ω^2)*μ*ϵ

resλ = 
      Solve[lambdakvadrat == (λ^2), λ]

FullSimplify[
      lambdakvadrat /. {γ -> 
            0, ϵri -> ϵrr*tgδ}]

vyr1 =  ϵ0 ϵrr μ (ω^2);
vyr2 = I (I + tgδ);

resμ = 
      Solve[(c^2) == (1/(ϵrr*ϵ0*μ)), μ]

vyr1 /. resμ[[1]]

Expand[vyr2]

vyr3 = 
      Normal[Series[(Sqrt[-1 + x]), {x, 0, 1}]] /. 
        x -> I*tgδ

vyr4 = (ω/c)*vyr3

resdal = Solve[{λ == (c/f), ω == 
              2*Pi*f}, {c, ω}][[1]]

Simplify[vyr4 /. resdal]

ParametricPlot[{Sin[fi], Sin[fi + 0.01]}, {fi, 0, 2  Pi}]