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Plot impedance transformation for selected matching network on smith chart


smithplot(mnobj) plots the impedance transformation from the source to load for the best matching network on a smith chart.


smithplot(___,Name,Value) plots the impedance transformation from the source to load on a Smith chart with additional properties given by Name, Value pair . For instance smithplot (MNOBJ, 'CircuitIndex',____, 'Z0', _____) plots the impedance transformation for the selected matching network circuit at the characteristic impedance, Z0 on a smith chart.

Properties not specified retain their default values.


For more name value pairs see, Tips.


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Create a new matchingnetwork and plot the impedance transformation of the second matching network circuit in the design.

f       = 2e9;          % Center frequency, Hz
Zin     = 150+75i;      % Source impedance, Ohms
Zl      = 75+15i;       % Load impedance, Ohms
Zo      = 75;           % characteristic impedance of system, Ohms

Design matching network object

n = matchingnetwork('CenterFrequency',f,'Bandwidth',1e8,           ...

View Circuit #2

ans = 
  circuit: Circuit element

    ElementNames: {'C'  'L'}
        Elements: [1x2 rf.internal.circuit.RLC]
           Nodes: [1 2 3]
            Name: 'auto_1'
        NumPorts: 2
       Terminals: {'p1+'  'p2+'  'p1-'  'p2-'}

Impedance transformation of Circuit #2 on a smith chart

hs = smithplot(n, 'Z0', Zo, 'CircuitIndex',2);

Input Arguments

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Matching network, specified as a matchingnetwork object.

Data Types: char | string

Name-Value Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Example: 'CircuitIndex',1

Selected matching network, specified as a positive scalar.

Data Types: double

Characteristic impedance, specified as scalar in ohms.

Data Types: double


  • To list other property Name,Value pairs in smithplot, use details(s) where s is a smithplot object. You can use the properties to extract any data from the Smith chart.

  • For a list of properties of smithplot, see .

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

Introduced in R2019a