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balunCoupledLine

Create multisection coupled-line balun on X-Y plane

Description

Use the balunCoupledLine object to create a multisection coupled-line balun with an unbalanced input and a balanced output. The output signal has a phase difference of 180 degrees.

Creation

Description

example

balun = balunCoupledLine creates a coupled-line balun in the microstrip form. The default properties are for a resonant frequency of 2.96 GHz.

example

balun = balunCoupledLine(Name=Value) sets Properties using one or more name-value arguments. For example, balunCoupledLine(OutputLineLength=0.0286) creates a coupled-line balun with an output line length of 0.0286 meters. Properties not specified retain their default values.

Properties

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Number of coupled-line sections, specified as a positive scalar. The minimum number of sections you can specify is two and the maximum number is five.

Example: balun = balunCoupledLine(NumCoupledLine=4)

Data Types: double

Length of the coupled line in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(CoupledLineLength=0.0254)

Data Types: double

Width of the coupled line in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(CoupledLineWidth=0.0005)

Data Types: double

Spacing between the coupled lines in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(CoupledLineSpacing=0.00015)

Data Types: double

Shape of the uncoupled-line section, specified as a shape object. The default shape of the uncoupled-line section is the ubendMitered shape. The default dimensions of the ubendMitered shape are: length of [0.0082 0.00453 0.0082], width of [0.002 0.002 0.002], and a miter diagonal of 0.002828.

Example: balun = balunCoupledLine(UncoupledLineShape=ubendMitered)

Data Types: char | string

Length of the quarter wave transformer used to extend the ports in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(OutputLineLength=0.0224)

Data Types: double

Width of the output line in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(OutputLineWidth=0.000253)

Data Types: double

Spacing between the output ports in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(OutputLineSpacing=0.022)

Data Types: double

Height of the coupled-line balun from the ground plane in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(Height=0.022)

Data Types: double

Width of the ground plane in meters, specified as a positive scalar.

Example: balun = balunCoupledLine(GroundPlaneWidth=0.032)

Example: double

Type of dielectric material used as a substrate, specified as a dielectric object. The default height of the substrate is 0.0013 meters.

Example: d = dielectric("RTDuriod"); balun = balunCoupledLine(Substrate=d)

Data Types: string | char

Type of metal used in the conducting layers, specified as a metal object.

Example: m = metal("Copper"); balun = balunCoupledLine(Conductor=m)

Data Types: string | char

Object Functions

chargeCalculate and plot charge distribution
currentCalculate and plot current distribution
designCoupledLineCalculate dimensions of coupled-line section for specified frequency
designUncoupledLineCalculate dimensions of uncoupled-line section for specified frequency
designOutputLineCalculate dimensions of output line section for specified frequency
feedCurrentCalculate current at feed port
layoutPlot all metal layers and board shape
meshChange and view mesh properties of metal or dielectric in PCB component
shapesExtract all metal layer shapes of PCB component
showDisplay PCB component structure or PCB shape
sparametersCalculate S-parameters for RF PCB objects

Examples

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Create a coupled-line balun using default properties.

balun = balunCoupledLine
balun = 
  balunCoupledLine with properties:

    NumCoupledLineSection: 3
        CoupledLineLength: 0.0153
         CoupledLineWidth: 4.0000e-04
       CoupledLineSpacing: 1.4000e-04
       UncoupledLineShape: [1x1 ubendMitered]
         OutputLineLength: 0.0124
          OutputLineWidth: 1.5300e-04
        OutputLineSpacing: 0.0110
                   Height: 0.0013
         GroundPlaneWidth: 0.0200
                Substrate: [1x1 dielectric]
                Conductor: [1x1 metal]

Visualize the coupled-line balun.

show(balun)

Figure contains an axes object. The axes object with title balunCoupledLine element contains 8 objects of type patch, surface. These objects represent PEC, feed, FR4.

Create a coupled-line balun using default properties.

balun = balunCoupledLine;

Change the substrate and the dielectric of the balun.

balun.Substrate = dielectric('Name',{'Teflon','Teflon'},'EpsilonR', ...
    [2.1 2.1],'LossTangent',[0 0],'Thickness',[0.8e-3 0.8e-3]);
balun.Height = 0.8e-3;

Visualize the balun.

show(balun)

Figure contains an axes object. The axes object with title balunCoupledLine element contains 9 objects of type patch, surface. These objects represent PEC, feed, Teflon.

Create a coupled-line balun with an OutputLineSpacing of 5 mm.

balun = balunCoupledLine('OutputLineSpacing',0.005);

Visualize the balun.

show(balun);

Figure contains an axes object. The axes object with title balunCoupledLine element contains 8 objects of type patch, surface. These objects represent PEC, feed, FR4.

Define the frequency at 4 GHz.

f = 4e9;

Create a coupled line balun object.

balun = balunCoupledLine
balun = 
  balunCoupledLine with properties:

    NumCoupledLineSection: 3
        CoupledLineLength: 0.0153
         CoupledLineWidth: 4.0000e-04
       CoupledLineSpacing: 1.4000e-04
       UncoupledLineShape: [1×1 ubendMitered]
         OutputLineLength: 0.0124
          OutputLineWidth: 1.5300e-04
        OutputLineSpacing: 0.0110
                   Height: 0.0013
         GroundPlaneWidth: 0.0200
                Substrate: [1×1 dielectric]
                Conductor: [1×1 metal]

show(balun)

Step 1: Design coupled line section

Design the coupled line section of the balun with an even mode impedance of 159 ohms and an odd mode impedance of 51 ohms. Use the helper function designCoupledLine.

[ClineL,ClineW,ClineS] = designCoupledLine(balun,f,'Z0e',159,'Z0o',51)
ClineL = 0.0107
ClineW = 4.2682e-04
ClineS = 1.4374e-04

Step 2: Design uncoupled line section

Design the uncoupled line section of the balun with the even and odd mode impedance of 59 ohms. Use the helper function designUncoupledLine.

[unclineL,unclineW] = designUncoupledLine(balun,f,'Z0',59,'LineLength',0.25)
unclineL = 0.0103
unclineW = 0.0018

Step 3: Design output line section

Design the output line section of the balun at the same frequency to extend the port 2 and port3. Use the helper function designOutputLine.

[OutL,OutW] = designOutputLine(balun,f,'Z0e',159,'Z0o',51,'Z0',59,'Zref',50)
OutL = 0.0109
OutW = 1.6115e-04

Set all the design dimensions to the coupled balun object.

balun.CoupledLineLength  = ClineL;
balun.CoupledLineWidth  = ClineW;
balun.CoupledLineSpacing  = ClineS;
UnCoupledLine = ubendMitered;
UnCoupledLine.Length  = [unclineL/2,unclineL/4,unclineL/2];
UnCoupledLine.Width   = [unclineW,unclineW,unclineW];
balun.UncoupledLineShape = UnCoupledLine;
balun.OutputLineLength = OutL;
balun.OutputLineWidth = OutW;
balun.OutputLineSpacing = OutL+ClineS;
gndW = 25e-3;
balun.GroundPlaneWidth = gndW; 
show(balun)

Analyze and plot the S-paramters of this balun.

s11 = sparameters(balun,linspace(3.5e9,4.5e9,31));

figure; rfplot(s11,1,1);
hold on; rfplot(s11,1,3)
hold on; rfplot(s11,1,2)

References

[1] Pozar, David M. Microwave Engineering. 4th ed. Hoboken, NJ: Wiley, 2012.

Version History

Introduced in R2022a