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Matching Network Designer

Design, visualize, and compare matching networks for one-port load

Description

The Matching Network Designer app lets you design, visualize, and compare matching networks for one-port load.

Using this app, you can:

  • Design two- and three-component lumped element matching networks at desired frequencies and unloaded-Q factors.

  • Provide source and load impedance as a one-port Touchstone file, scalar impedance, RF circuit object, RF network parameter object, Antenna Toolbox™ object, or as an anonymous function.

    Note

    • To load one-port circuit object to the app, you must set ports to your circuit object using the setports function.

    • To use an Antenna Toolbox object, you must have an Antenna Toolbox license.

    • One-port Touchstone files include S1P, Z1P, and Y1P file types.

  • Sort the matching networks using constraints such as operating frequency range and power wave S-parameters.

  • Plot power wave S-parameters [1] of the matching network on a Smith™ chart and Cartesian plot.

  • Plot voltage standing wave ratio (VSWR) and impedance transformation plots.

  • Plot magnitude, phase, real, and imaginary parts of power wave S-parameters of the matching network.

  • Export selected networks as circuit objects or power wave S-parameters as sparameters objects.

Available Configurations

The app toolstrip contains these network configurations that you can use to design matching networks:

  • Pi-Topology

  • T-Topology

  • L-Topology

  • 3-Components

Matching Network Designer app

Open the Matching Network Designer App

  • MATLAB® Toolstrip: On the Apps tab, under Signal Processing and Communications, click the Matching Network Designer app icon.

  • MATLAB command prompt: Enter matchingNetworkDesigner.

Examples

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Type this command at the command line to open the Matching Network Designer app.

matchingNetworkDesigner

Select New under File section to start a new session. In the New Session window, specify the design requirements:

  • Zs SourceScalar Complex Impedance

  • Impedance (Ohms)50+2i.

  • Zl SourceTouchstone File

  • File Namedipole_example.s1p

  • Center Frequency1.5e9 and

  • Bandwidth750e6.

The app only recognizes one-port Touchstone files and converts the center frequency and bandwidth to Hz.

mnw1_1.png

Select Start session. In the toolstrip of the app window, select 3-Components under the Configuration section and select Generate to generate the matching network. From the Matching Network Browser pane, select the nodes. For the purpose of this example, select auto_1. The Quality Factor is populated based on the data entered in the New Session window.

mnw_ex11.png

Set constraints to sort the three-component matching networks. To do this, click Manage Constraints. In the Design Constraints window, click add constraint button.png button and add the constraints. Set the constraint to:

abs(Parameter)S11

Condition<

Goal (dB) — –15

Min Frequency (GHz)1.4500

Max Frequency (GHz)1.5400

Weight1

Select Active and click OK.

mnw1_3.png

The matching networks are sorted based on the constraints and the nodes are rearranged under the Matching Network Browser pane.

mnw_ex12.png

Compare the power wave S-parameter results between the nodes. For the purpose of this example, compare the power wave S-parameter results between auto_1 and auto_3 nodes. To do this, select the auto_1 and auto_3 nodes using the Ctrl key. The results are displayed in the Cartesian and Smith plot.

mnw_ex13.png

Deselect the auto_3 node. To visualize the impedance transformation of the auto_1 node, select Impedance Transformation under Smith Plot or select the ZTransform window on the right hand side of the app.

mnw_ex14.png

Design a narrow-band double tuning L-section matching network between a resistive source and a capacitive load in the form of a small monopole. This example designs an L-section matching network consisting of two inductors. The equivalent source impedance is 50 ohms and the load is a monopole with resonant frequency of around 1 GHz. The load (antenna) impedance is at 500 MHz, which is half the resonant frequency.

load_antenna = design(monopole,1e9);
sparams_load = sparameters(load_antenna,linspace(0.45e9,0.55e9,101));

To open the Matching Network Designer app, type this command at the command line.

matchingNetworkDesigner

Select New under File section to start a new session. In the New Session window, specify the requirements:

  • Zs SourceScalar Complex Impedance

  • Impedance (Ohms)50

  • Zl SourceS-,Y-, or Z-parameter Object

  • Variable Namesparams_load

  • Center Frequency500e6 and

  • Bandwidth10e6.

The app converts the center frequency and bandwidth to Hz.

mnw2_1.png

Select Start Session. In the toolstrip of the app window, select L-Topology under Configuration section and select Generate to generate the matching network. From the Matching Network Browser pane, select the nodes. For the purpose of this example, select auto_1.

mnw_ex21.png

To plot the VSWR, select VSWR under Cartesian plot.

mnw2_3.png

Design a pi-matching network with circuit objects. For the purpose of this example, the custom pi-matching network consists of two capacitors and an inductor.

Create a circuit object.

ckt = circuit('test_ckt2');

Create two capacitors, C1 and C2 with the capacitance of 3.35 pF and 2.917 pF.

c1 = capacitor(3.35e-12,'C1');
c2 = capacitor(2.917e-12,'C2');

Create a 5.44 nH inductor.

l = inductor(5.44e-9,'L');

Add C1 to the node [1,0] of the circuit object.

add(ckt,[1,0],c1);

Add L to the node [1,2] of the circuit object.

add(ckt,[1,2],l);

Add C2 to the node [2,0] of the circuit object.

add(ckt,[2,0],c2);

Save the circuit object.

save('test_file2.mat','ckt');

Set ports to the circuit object and resave the circuit object in MAT file type.

setports(ckt,[1 0],[2 0]);
save('test_file2.mat','ckt');

Type this command at the command line to open the Matching Network Designer app.

matchingNetworkDesigner

Select New under File section to start a new session. In the New Session window, specify the design requirements:

  • Zs SourceScalar Complex Impedance

  • Impedance (Ohms)50

  • Zl SourceTouchstone File

  • File Namedipole_example.s1p

  • Center Frequency1.5e9 and

  • Bandwidth750e6

Select Import Circuit to import the custom pi-matching network designed in this example. Select node test_ckt2 under Matching Network Browser pane.

importmnw.png

S11 and S21 plot of the custom pi-matching network is displayed under Cartesian plot.

Related Examples

Programmatic Use

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matchingNetworkDesigner opens the Matching Network Designer app to design, visualize, and compare one-port narrowband matching networks.

matchingNetworkDesigner(mnnetwork) opens a matching network saved using the Matching Network Designer app. mnnetwork is a MAT file.

Tips

  • Use this expression to set design constraints: |Parameter| Condition 10^(Goal (dB)/20). For example, |S21| > 10^(-3/20) implies that matching network circuits are sorted with S21 greater than -3 dB as a design constraint. In linear scale the expression can be rewritten as |S21| > 0.7079.

Algorithms

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References

[1] Kurokawa, K. “Power Waves and the Scattering Matrix.” IEEE Transactions on Microwave Theory and Techniques 13, no. 2 (March 1965): 194–202. https://doi.org/10.1109/TMTT.1965.1125964.

[2] Ludwig, Reinhold, and Gene Bogdanov. RF Circuit Design: Theory and Applications. Upper Saddle River, NJ: Prentice-Hall, 2009.

Version History

Introduced in R2021a