How to plot Smith chart?

Hello. I need to plot Smith chart, having frequency, VSWR, reflection coefficient and phase. I'm fairly new to matlab environment and not sure how to achieve it. Tried already this from mathworks website, it didn't even seemed remotely okay. As it says, I've tried to plot reflection coefficient as gamma. Screen with my data and result I've got:

[Muhammad Syafiq Bin Salahudin]

Hi,

Is there any way to compile these codes into MATLAB App GUI?

[Janakinadh]

MATLAB's smithplot is compatible with uipanel. An uipanel is a common container in MATLAB Apps.

Usage:

smithplot('Parent', uipanel)

You can use appdesigner to easily build App GUI in MATLAB. That App can have a smithplot live in a panel.

Also see: Matching Network App where a smithplot is plotted in an uipanel to plot S-parameters and impedance transformation.

Answer 1

[John BG]

Hi Mr Taker

There are many ways to plot data on MATLAB Smith charts

1.- basic plot of single impedance

clc;clear all;format long; 
Z0=100;sm1=smithchart;
ZL1=150-1j*200;f0=3e9; % Hz

gamma_L=(ZL1-Z0)/(ZL1+Z0); 
% show ZL1 on Smith chart adding text showing values
if imag(ZL1)<0
sign1='-';
else
    sign1='+';
end

hold all;plot(real(gamma_L),imag(gamma_L),'ro','LineWidth',1.5);
str1=['ZL =' num2str(real(ZL1)) sign1 'j' num2str(abs(imag(ZL1))) ' \rightarrow'];
text(real(gamma_L),imag(gamma_L)+.01,str1,'Color','blue','FontSize',20,'HorizontalAlignment','right','VerticalAlignment','middle');

2.- solving a basic single stub ZLoad match:

the functions I use are as follows:

function [x_data,y_data]=Smith_plotGammaCircle(ax,Z,Z0)
% plot SWR circle, lossless TL

gamma=z2gamma(Z,Z0);  
r=abs(gamma); 
alpha=0:2*pi/100:2*pi;                                       
hold all;
sub_hp2=plot(ax,r*cos(alpha),r*sin(alpha),'-','LineWidth',.5,'Color',[1 .2 0])   
x_data=sub_hp2.XData
y_data=sub_hp2.YData

end

function Smith_plotRefLine2PhaseCircle(ax,Z,Z0)
% plot reference line from origin through ZL to phase reference circle

gamma_L=z2gamma(Z,Z0);                                
a=atan(imag(gamma_L)/real(gamma_L));
plot(ax,[0 cos(a)],[0 sin(a)],'Color',[0 0.7 0],'LineWidth',1)           

end

function a=Smith_plotRefLine2PhaseCircle(ax,Z,Z0)
% plot reference line from origin oppsite to ZL to phase reference circle
% it plots ref line through YL

gamma_L=(Z-Z0)/(Z+Z0)

a=angle(gamma_L)
plot(ax,[0 -real(exp(1j*a))],[0 -imag(exp(1j*a))],'Color',[0 0.7 0],'LineWidth',1)           

end

function Smith_plotZ(ax,Z,Z0)
% add text showing ZL R+jX data, Smith Chart generated externally

gamma=z2gamma(Z,Z0);  
plot(ax,real(gamma),imag(gamma),'ro','LineWidth',1.5)

if imag(Z)<0
sign1='-';
else
    sign1='+';
end
hold all;plot(ax,real(gamma),imag(gamma),'ro','LineWidth',1.5);
str1=['ZL =' num2str(real(Z)) sign1 'j' num2str(abs(imag(Z))) ' \rightarrow'];
text(ax,real(gamma),imag(gamma)+.01,str1,'Color','blue','FontSize',20,'HorizontalAlignment','right','VerticalAlignment','middle');

end

3.- adding reactance/resistance circle sections and a legend

Z0=75; ZL=90+1j*60;

sm1=smithchart; ax=gca; hold all; 
sm1.Values = [.1 .2 .3 .5 1 1.5 2 3.5 5;1 1.5 2 3.5 5 5 5 15 30]
sm1.SubColor=[.2 .2 .2]

gamma_ZL=(ZL-Z0)/(ZL+Z0); gamma_YL=-gamma_ZL
plot(ax,real(gamma_ZL),imag(gamma_ZL),'ro','LineWidth',1.5)
plot(ax,real(gamma_YL),imag(gamma_YL),'bo','LineWidth',1.5)

hl1=legend(ax,{'ZL','YL'}, 'Location','bestoutside');title(hl1,'points')

Smith_plotRefLine2PhaseCircle(ax,ZL,Z0)
[x_circ1,y_circ1]=Smith_plotGammaCircle(ax,ZL,Z0);
[x_circ2,y_circ2]=Smith_plotRcircle(ax,Z0,Z0);

[x_target,y_target]=kreuzungen(x_circ1,y_circ1,x_circ2,y_circ2)

plot(ax,x_target(1),y_target(1),'ro','LineWidth',1.5)
plot(ax,x_target(2),y_target(2),'ro','LineWidth',1.5)

The function kreuzungen appended to these lines was developed by Douglas M. Schwarz dmschwarz=ieee*org, dmschwarz=urgrad*rochester*edu function available in this forum too.

4.- there are different custom toolboxes available in MATLAB file exchange. One that allows to set Z0 as input to a Smith chart related function of the tool set is

https://uk.mathworks.com/matlabcentral/fileexchange/22996-rf-utilities-v1-2

by Neil Tucker

The drawback of Tucker's is that his core function is named exactly as MATLAB RF toolbox smith, the problem being that while MATLAB’s smith does not take in Z0, MATLAB's smith only plots normalised impedances/admittances. When attempting to call Tucker's smith MATLAB returns zero, I got it working by renaming Tucker's smith function.

5.- Although encouraging Smith chart functions development with MATLAB, I am now learning KEYSIGHT ADS, and it's the right tool to solve RF circuits with Smith Chart plots.

http://www.keysight.com/en/pc-1475688/keysight-eesof-electronic-design-automation-EDA-software?nid=-34360.0&cc=GB&lc=eng

.

So, Taker if you find this answer useful would you please be so kind to mark my answer as Accepted Answer?

To any other reader, please if you find this answer of any help solving your question,

please click on the thumbs-up vote link,

thanks in advance

John BG

<mailto:[e-mail] [e-mail]>

EDIT: deleted Douglas Schwarz's copyright code.

[Ammar Babikir]

Hi, I actually tried using your first code

if true
 clc;clear all;format long; 
Z0=100;
sm1=smithchart;
ZL1=150-1j*200;f0=3e9; % Hz
gamma_L=(ZL1-Z0)/(ZL1+Z0); 
% show ZL1 on Smith chart adding text showing values
if imag(ZL1)<0
sign1='-';
else
  sign1='+';
end
hold all;plot(real(gamma_L),imag(gamma_L),'ro','LineWidth',1.5);
str1=['ZL =' num2str(real(ZL1)) sign1 'j' num2str(abs(imag(ZL1))) ' \rightarrow'];
text(real(gamma_L),imag(gamma_L)+.01,str1,'Color','blue','FontSize',20,'HorizontalAlignment','right','VerticalAlignment','middle');
end

I ended up getting this error when I run it:

Attempt to execute SCRIPT smithchart as a function: C:\Users\Ammar\Documents\MATLAB\smithchart.m Error in smith_ch_calc (line 3) sm1=smithchart;

I was wondering why it's giving me that error.

[Jan]

@Ammar: smithchart is a function of Matlab's RF-Toolbox. The error message implies that you have created a function with the same name in the folder C:\Users\Ammar\Documents\MATLAB. Simply rename this function to avoid a confusion.

[John BG]

Hi Ammar Babikir

there is an early (2003) collection of functions available in the MATLAB file exchange that has a function called smith.

https://uk.mathworks.com/matlabcentral/fileexchange/3499-smith-chart-plotting-routine?s_tid=srchtitle

When one tries to run that smith function, that has many input fields, the same error message shows up.

There's this other group of Smith chart related functions

https://uk.mathworks.com/matlabcentral/fileexchange/47330-smith-chart-zip?s_tid=srchtitle

that has a function called exactly smithchart, and again, it's going cause anything but conflict.

So, make sure that whatever other Smith chart tools you may have downloaded, for earlier MATLAB versions, for evaluation, make sure that the files are not in the MATLAB working folder.

Regards

John BG

<mailto:[e-mail] [e-mail]>

[Harrison Norris]

Hey, looking through your code. How does your Smith_plotRcircle function work and I can find no mention of any kind of kreuzungen function other than on this page. I know its been awhile since posting, just looking for Info.

Thanks,

Harrison Norris

Answer 2

[MathWorks Support Team]

MATLAB's smithplot is compatible with uipanel. An uipanel is a common container in MATLAB Apps.

Usage:

smithplot('Parent', uipanel)

You can use appdesigner to easily build App GUI in MATLAB. That App can have a smithplot live in a panel.

Also see: Matching Network App where a smithplot is plotted in an uipanel to plot S-parameters and impedance transformation.