Pwr=[-60,-55,-50,-45,-40,-35,-30,-25,-20,-10,-5,0,5,10]';
Voltage11=[2.12,2.10,2.03,1.93,1.83,1.71,1.59,1.47,1.35,1.10,0.97,0.85,0.71,0.61]';

Voltage11=spline(Pwr,Voltage11,linspace(-60,10,15));
PwrSmooth=linspace(-60,10,15);

Voltage29=[2.14,2.14,2.14,2.14,2.14,2.14,2.13,2.12,2.09,1.94,1.84,1.73,1.61,1.49];
Voltage29=spline(Pwr,Voltage29,linspace(-60,10,15));

Voltage55=[2.16,2.16,2.16,2.16,2.16,2.16,2.16,2.15,2.14,2.13,2.10,2.04,1.94,1.83];
Voltage55=spline(Pwr,Voltage55,linspace(-60,10,15));

plot(PwrSmooth,Voltage11)