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coplanarWaveguide

Create coplanar waveguide transmission line

Description

Use the coplanarWaveguide object to create a coplanar waveguide transmission line. Coplanar waveguide is a common type of transmission line used in any PCB implementation of RF and microwave components. A coplanar waveguide transmission line has a center conductor strip and two ground planes. One ground plane is the layer that acts as the conductor strip and the other ground plane is the bottom layer.

To analyze the behavioral model of a coplanar waveguide transmission line, set the Behavioral property in the sparameters object function to true or 1.

Creation

Description

example

cpgw = coplanarWaveguide creates a default coplanar waveguide transmission line with a Teflon substrate. The default property values are for a 50 ohm transmission line.

cpgw = coplanarWaveguide(Name=Value) sets Properties using one or more name-value arguments. For example, coplanarWaveguide(Width=0.0047) creates a coplanar waveguide transmission line of width 0.0047 meters. Properties not specified retain their default values.

Properties

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Length of the coplanar waveguide transmission line in meters, specified as a positive scalar.

Example: cpgw = coplanarWaveguide(Length=0.0300)

Data Types: double

Width of the coplanar waveguide transmission line in meters, specified as a positive scalar.

Example: cpgw = coplanarWaveguide(Width=0.0047)

Data Types: double

Distance between the transmission line and the adjacent top layer metal of the ground plane, specified as a positive scalar in meters.

Example: cpgw = coplanarWaveguide(Spacing=3.0000e-04)

Data Types: double

Distance between the vias, specified as a two-element vector of positive elements.

Example: cpgw = coplanarWaveguide(ViaSpacing=[0.0021 0.0060])

Data Types: double

Diameter of the via in meters, specified as a positive scalar.

Example: cpgw = coplanarWaveguide(ViaDiameter=7.0000e-04)

Data Types: double

Height of the coplanar waveguide transmission line from the ground plane, specified as a positive scalar in meters.

Example: cpgw = coplanarWaveguide(Height=0.0020)

Data Types: double

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

Example: cpgw = coplanarWaveguide(GroundPlaneWidth=0.0350)

Data Types: double

Type of dielectric material used as a substrate, specified as a dielectric object.

Example: d = dielectric("FR4"); cpgw = coplanarWaveguide(Substrate=d)

Data Types: string | char

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

Example: m = metal("PEC"); cpgw =coplanarWaveguide(Conductor=m)

Data Types: string | char

Object Functions

chargeCalculate and plot charge distribution
currentCalculate and plot current distribution
designDesign coplanar waveguide transmission line around particular frequency
feedCurrentCalculate current at feed port
getZ0Calculate characteristic impedance of transmission line
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 coplanar waveguide transmission line.

waveguide = coplanarWaveguide
waveguide = 
  coplanarWaveguide with properties:

              Length: 0.0231
               Width: 0.0039
             Spacing: 2.0000e-04
          ViaSpacing: [0.0011 0.0070]
         ViaDiameter: 5.0000e-04
              Height: 0.0016
    GroundPlaneWidth: 0.0300
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]

View the coplanar waveguide transmission line.

show(waveguide)

Figure contains an axes object. The axes object with title coplanarWaveguide element contains 48 objects of type patch, surface. These objects represent PEC, feed, Teflon.

Calculate the S-parameters of the waveguide from 1-10 GHz.

sparam = sparameters(waveguide,1e9:0.3e9:10e9)
sparam = 
  sparameters: S-parameters object

       NumPorts: 2
    Frequencies: [31x1 double]
     Parameters: [2x2x31 double]
      Impedance: 50

  rfparam(obj,i,j) returns S-parameter Sij

Plot the S-parameters.

rfplot(sparam)

Figure contains an axes object. The axes object contains 4 objects of type line. These objects represent dB(S_{11}), dB(S_{21}), dB(S_{12}), dB(S_{22}).

Create a coplanar waveguide transmission line using a gold substrate as the dielectric.

txem = coplanarWaveguide;
txem.Conductor = metal("Gold");

Design the coplanar waveguide at a frequency of 3 GHz, line length of 0.5 meters, and impedence of 75 ohms.

txem = design(txem,3e9,LineLength=0.5,Z0=75);
show(txem)

Figure contains an axes object. The axes object with title coplanarWaveguide element contains 72 objects of type patch, surface. These objects represent Gold, feed, Teflon.

Compute and plot the behavioral S-parameters of the waveguide.

spar = sparameters(txem,3e9,Behavioral=true);
rfplot(spar)

Figure contains an axes object. The axes object contains 4 objects of type line. These objects represent dB(S_{11}), dB(S_{21}), dB(S_{12}), dB(S_{22}).

References

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

Introduced in R2021b