Using smithplot for a smith chart, can't get normalized impedance values to display properly

Question

Emre Hayatoglu 2023-2-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1914515-using-smithplot-for-a-smith-chart-can-t-get-normalized-impedance-values-to-display-properly

评论： Emre Hayatoglu 2023-2-17

Hey guys. As the title suggests, I've been trying to plot the normalized impedance values depending on ω, however when I call the command, the values are horribly misaligned. Refer to the code and the screenshot for further info. What am I doing wrong?

clc;
s = smithplot;
% Define the frequency range (20 MHz to 50 MHz)
f_start = 20e6;
f_stop = 50e6;
f_step = 1e6;
f = f_start:f_step:f_stop;
% Define the load parameters
C = 200e-12;
L = 100e-9;
R = 1000;
% Calculate the angular frequency
omega = 2*pi*f;
% Calculate the reactance
X = omega * L - 1 ./ (omega * C);
% Calculate the impedance of the load
ZL = R + 1i * X;
% Define the characteristic impedance of the transmission line (Z0 = 120 * pi Ohms)
Z0 = 120 * pi;
% Normalize the impedance of the load
ZL_normalized = ZL / Z0;
% Plot the normalized impedance on a Smith chart
hold all;
plot(real(ZL_normalized),imag(ZL_normalized),'LineWidth',2);

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Star Strider 2023-2-17

在 MATLAB Online 中打开

You need to plot directly to the smithplot.

Try something like this —

% clc;

% s = smithplot;

% Define the frequency range (20 MHz to 50 MHz)

f_start = 20e6;

f_stop = 50e6;

f_step = 1e6;

f = f_start:f_step:f_stop;

% Define the load parameters

C = 200e-12;

L = 100e-9;

R = 1000;

% Calculate the angular frequency

omega = 2*pi*f;

% Calculate the reactance

X = omega * L - 1 ./ (omega * C);

% Calculate the impedance of the load

ZL = R + 1i * X;

% Define the characteristic impedance of the transmission line (Z0 = 120 * pi Ohms)

Z0 = 120 * pi;

% Normalize the impedance of the load

ZL_normalized = ZL / Z0;

% Plot the normalized impedance on a Smith chart

hold all;

s = smithplot(real(ZL_normalized),imag(ZL_normalized),'LineWidth',2);

I do not know what you are plotting, and while I understand about Smith charts, I do not have any of the Toolboxes that support them, so I have no direct experience with them in MATLAB.

.

Emre Hayatoglu 2023-2-17

在 MATLAB Online 中打开

I fixed the issue with the following code:

hckt = circuit('new_circuit1');
hC1= add(hckt,[1 2],capacitor(200e-12));
hR1 = add(hckt,[2 3],resistor(1000));
hL1 = add(hckt,[3,4],inductor(100e-9));
setports (hckt,[1 4]);
disp(hckt)
freq = linspace(20e6,50e6);
ckt_sparameters = sparameters(hckt,freq,120*pi);
hold all;
smithplot(ckt_sparameters,[1,1],'LegendLabels','Reflection Coefficient');