Plotting on Smith chart

Hello,

I have Real and imaginary impedances on an Excel sheet which I pull into matlab. I then normalise and plot on smith chart using the command "smithplot". But I see that the plot on smithchart isnt right. Help is appreciated. Please see the enclosed excel sheet and matlab script.

Thanks.

Answer 1

[Cris LaPierre]

I would probably create the smithplot this way.

data = readtable('1kHz.xlsx');
Z0 = 50;
Zl=data.Rohm + 1i*data.Xohm;
gamma = z2gamma(Zl,Z0);
smithplot (gamma,'+g');

[Cris LaPierre]

For your code, make sure you know what the inputs to smithplot are. Figure(1) doesn't work because there is no syntax for inputs r,x. Figure(2) is close. One change will get it to work. You compute gamma with

gamma = (y-50)/(y+50);

This will perform a matrix division. You want elementwise division, so use the "./" elementwise operator.

gamma = (y-50)./(y+50);

See this documentation page for more details.