par[a_, 
          b_] := (((((a + b)/(a*b))))^(-1));
ser[a_, b_] := a + b;

Zz = 10.  + 3.  I; μF = (10^(-6));
L1 = 0.09; L2 = 0.2; L3 = 0.2;
ω = 100.  Pi;
z1 = ser[I*ω*L3, Ro];
z2 = 
        par[(1/(I*ω*Cap)), z1] // 
          Simplify;
z3 = ser[I*ω*L2, z2];
z4 = par[Zz, z3];
zsum = ser[I*ω*L1, z4];
uz[Ro_, Cap_] = (z4/zsum);
uRopul = Abs[uz[100, 1  μF]];
fittnes[Ro_, Cap_] = 
        Abs[uRopul - Abs[uz[Ro, Cap]]];
kond[Ro_] := 
      Cap /. FindMinimum[
            fittnes[Ro, Cap], {Cap, 0, 
              5  μF}][[2]]
chyba[
          Ro_] := FindMinimum[
            fittnes[Ro, Cap], {Cap, 0, 5  μF}][[1]];

Romin = 100;
Romax = 147;
Plot[kond[Ro], {Ro, Romin, Romax}, 
      AxesLabel -> {"Ro", "C"}]