Main Content

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

expand all

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.

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.

Set constraints to sort the three-component matching networks. To do this, click Manage Constraints. In the Design Constraints window, click 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.

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

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 displayed in the Cartesian and Smith plot.

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.

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.

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.

To plot the VSWR, select VSWR under Cartesian plot.

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.

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

Related Examples

Programmatic Use

expand all

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.

Algorithms

expand all

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.

Introduced in R2021a