Plotting reflection coefficient as func. of frequency

Hi, How may I make a similar plot in MATLAB? It's a special Smith Chart showing the normalized load Z = -0.6 + jx, where 0.75<x<1.5 (the values of x were determined based on the desired range of frequencies, 5<f<10GHz).

Answer 1

[Janakinadh]

Hello Yuval,

MATLAB currently does not have a compressed smith chart to plot data for r < 0. If your r is positive (r>=0) then you can do something like this:

r           = 0.6;
x           = linspace(0.75,1.5);
data        = r+1j*x;
Zdata       = 50;
Zdesired    = 50;

figure;
smithchart(z2gamma(data*Zdata,Zdesired));

If you want your data to be a function of frequency, you can create a rfdata.data object and then use smith function, something like this:

Freq                     = linspace(5e9, 10e9);
temp                     = rfdata.data;
temp.Freq                = Freq;                        % Your frequency data goes here
temp.S_Parameters        = zeros(2,2,numel(Freq));
temp.S_Parameters(1,1,:) = z2gamma(data*Zdata,Zdesired); % Your data(freq) goes here 

figure; smith(temp, 'S11');

Hope this helps!

- Janakinadh