Val_nom = [16.2, 31.3, 48.7, 100.9, 231.2, 489, 974, 1460, 2128, 4672, 6959, 11020];
ZE=600;
Zl=Val_nom;
ae=6.6+20*log10( abs((Zl+ZE)./(Zl-ZE)) )