balunCoupledLine

Create multisection coupled-line balun on X-Y plane

Since R2022a

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

Syntax

balun = balunCoupledLine

balun = balunCoupledLine(Name=Value)

Description

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

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

NumCoupledLineSection — Number of coupled-line sections

3 (default) | positive scalar

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

CoupledLineLength — Length of coupled line

0.01526 (default) | positive scalar

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

Example: balun = balunCoupledLine(CoupledLineLength=0.0254)

Data Types: double

CoupledLineWidth — Width of coupled line

0.0004 (default) | positive scalar

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

Example: balun = balunCoupledLine(CoupledLineWidth=0.0005)

Data Types: double

CoupledLineSpacing — Distance between coupled lines

0.00014 (default) | positive scalar

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

Example: balun = balunCoupledLine(CoupledLineSpacing=0.00015)

Data Types: double

UncoupledLineShape — Shape of uncoupled-line section

ubendMitered (default) | shape object

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

OutputLineLength — Length of quarter wave transformer

0.0124 (default) | positive scalar

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

OuputLineWidth — Width of output line

0.000153 (default) | positive scalar

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

Example: balun = balunCoupledLine(OutputLineWidth=0.000253)

Data Types: double

OutputLineSpacing — Distance between output ports

0.011 (default) | positive scalar

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

Example: balun = balunCoupledLine(OutputLineSpacing=0.022)

Data Types: double

Height — Height of coupled-line balun from ground plane

0.0013 (default) | positive scalar

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

GroundPlaneWidth — Width of ground plane

0.0200 (default) | positive scalar

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

Example: balun = balunCoupledLine(GroundPlaneWidth=0.032)

Example: double

Substrate — Type of dielectric material

dielectric object

Type of dielectric material used as a substrate, specified as a dielectric object. The default height of the substrate is 0.0013 meters. The dielectric material in a balunCoupledLine object with default properties is FR4.

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

Data Types: string | char

Conductor — Type of metal used in conducting layers

metal object

Type of metal used in the conducting layers, specified as a metal object. The type of metal in a balunCoupledLine object with default properties is PEC.

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

Data Types: string | char

Object Functions

charge	Calculate and plot charge distribution
current	Calculate and plot current distribution
designCoupledLine	Calculate dimensions of coupled-line section for specified frequency
designUncoupledLine	Calculate dimensions of uncoupled-line section for specified frequency
designOutputLine	Calculate dimensions of output line section for specified frequency
feedCurrent	Calculate current at feed port
layout	Plot all metal layers and board shape
mesh	Change and view mesh properties of metal or dielectric in PCB component
shapes	Extract all metal layer shapes of PCB component
show	Display PCB component structure or PCB shape
sparameters	Calculate S-parameters for RF PCB objects

Examples

Default Coupled-Line Balun

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)

Coupled-Line Balun with Multiple Dielectric Layers

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)

Customize Coupled-Line Balun

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

balun = balunCoupledLine('OutputLineSpacing',0.005);

Visualize the balun.

show(balun);

Design Coupled Line Balun at 4 GHz

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-parameters 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