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Plot measurement data on a Smith chart



smithplot(data) creates a Smith chart based on the input data specified in data.


  • A Smith chart is commonly used to display the relationship between a reflection coefficient, typically S11 or S22, and a normalized impedance.

  • The smithplot function replaces the smithchart function. (since R2023b)

smithplot(frequency,data) creates a Smith chart based on frequency and data values.

smithplot(ax,___) creates a Smith chart with a user defined axes handle, ax, instead of the current axes handle. Axes handles are not supported for network parameter objects. This parameter can be used with either of the two previous syntaxes.

smithplot(hnet) plots all the network parameter objects in hnet.

smithplot(hnet,i,j) plots the (i, j)th parameter of hnet. hnet is a network parameter object.

smithplot(hnet,[i1,j1;i2,j2;....,in,jn]) plots multiple parameters (i1, j1, i2, j2, …, in, jn) of hnet. hnet is a network parameter object.

s = smithplot(___) returns a Smith chart object handle so you can customize the plot and add measurements.

s = smithplot('gco') returns a Smith chart object handle of the current plot. This syntax is useful when the function handle, p was not returned or retained.

smithplot(___,Name,Value) creates a Smith chart with additional properties specified by one or more name-value pair arguments. Name is the property name and Value is the corresponding property value. You can specify several name-value pair arguments in any order as Name1, Value1, ..., NameN, ValueN. Properties not specified retain their default values.

For list of properties, see SmithPlot Properties (RF Toolbox).


The property 'Parent' might be used to control the location where Smith chart gets plotted. Target can be figure, UI figure, UI panel, etc.


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Create a strip dipole antenna on the Y-Z plane. Calculate the complex S-parameters of the dipole antenna from 60 MHz to 90 MHz, with an interval of 150 kHz.

d = dipole; 
freq = linspace(60e6,90e6,200);
s = sparameters(d,freq);

Plot the S11 on a Smith chart.

hg = smithplot(s,1,1,'GridType','ZY');
hg.LineStyle = '--'

hg = 
  smithplot with properties:

         Data: [200x1 double]
    Frequency: [200x1 double]

   Show all properties, methods

Smith Plot Interactive Menu

Use the Smith chart interactive menu for changing line and marker styles.

Plot the Smith chart of S-parameters of dipole d.


Right click on the S11 line to reveal interactive menu, DATASET 1. Set Line style to '-.' and Properties...>Line Width to '2' to change the line style and width of S11 line on the Smith chart.

You can see the changes you made on the Smith chart.

Read the S-parameter data.

amp = read(rfckt.amplifier,'default.s2p');
Sa = sparameters(amp);

Convert the S-parameter data to Y-parameter and plot it on a Smith plot.

Ya = yparameters(Sa);

Add Z-parameter data to the same plot.

Za = zparameters(Sa);
Z12 = rfparam(Za,1,2);
Freq = Za.Frequencies;
s = smithplot('gco');
add(s, Freq, Z12);

Input Arguments

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Input data, specified as a complex vector or complex matrix.

For a matrix D, the columns of D are independent data sets. For N-by-D arrays, dimensions 2 and greater are independent data sets.

Data Types: double
Complex Number Support: Yes

Frequency data, specified as a real vector.

Data Types: double

Input objects, specified as a network parameter object.

Data Types: double

RF budget object, specified as a rfbudget (RF Toolbox) object.

Output Arguments

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Smith chart object handle. You can use the handle to customize the plot and add measurements using MATLAB® commands.


  • To list all the property Name,Value pairs in smithplot, use details(s). You can use the properties to extract any data from the Smith chart. For example, s = smithplot(data,'GridType','Z') displays the impedance data grid from the Smith chart.

  • For a list of properties of smithplot, see SmithPlot Properties (RF Toolbox).

  • You can use the smithplot interactive menu to change the line and marker styles.

Version History

Introduced in R2017b

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See Also