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designCoupledLine

Calculate dimensions of coupled-line section for specified frequency

Description

[Length,Width,Spacing] = designCoupledLine(balunobj,frequency) calculates the dimensions of the coupled line section of a coupled-line balun around a specified frequency.

Note

designCoupledLine is the first step in designing a coupled line balun. This function is succeeded by designUncoupledLine and designOutputLine as the second and third step, respectively.

example

___ = designCoupledLine(___,Name=Value) calculates the dimensions of the coupled-line section of a coupled-line balun with additional options specified using name-value arguments.

Note

PCB components designed using the design function operate around the specified frequency with a 10-15% tolerance.

Examples

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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)

Input Arguments

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Coupled-line balun, specified as a balunCoupledLine object.

Example: balunobj = balunCoupledLine; design(balunobj,2e9) designs a coupled-line balun around a frequency of 2 GHz and returns the CoupledLineLength, CoupledLineWidth, and CoupledLineSpacing dimensions of the coupled line balun.

Design frequency of coupled-line balun, specified as a real positive scalar in hertz.

Example: 55e6

Data Types: double

Name-Value Arguments

Example: Z0o=61

Even mode impedance, specified as a positive scalar in ohms.

Data Types: double

Odd mode impedance, specified as a positive scalar in ohms.

Data Types: double

Output Arguments

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Length of the coupled-line section, returned as a positive scalar.

Width of the coupled-line section, returned as a positive scalar.

Spacing between the coupled-line sections, returned as a positive scalar.

Version History

Introduced in R2022a