Plotting reflection coefficient as func. of frequency

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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).

Answers (1)

Janakinadh
Janakinadh on 5 Jun 2017
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

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