coplanarWaveguide

Create coplanar waveguide transmission line

Since R2021b

Description

Use the coplanarWaveguide object to create a coplanar waveguide transmission line. A 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.

Note

This PCB object supports behavioral modeling. For more information, see Behavioral Models. To analyze the behavioral model for a coplanar waveguide, set the Behavioral property in the sparameters function to true or 1

Creation

Syntax

cpgw = coplanarWaveguide

cpgw = coplanarWaveguide(Name=Value)

Description

cpgw = coplanarWaveguide creates a default coplanar waveguide transmission line with a Teflon substrate and default property values 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

Length — Length of coplanar waveguide transmission line

0.0231 (default) | positive scalar

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

Example: cpgw = coplanarWaveguide(Length=0.0300)

Data Types: double

Width — Width of coplanar waveguide transmission line

0.0039 (default) | positive scalar

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

Example: cpgw = coplanarWaveguide(Width=0.0047)

Data Types: double

Spacing — Distance between transmission line and adjacent ground plane

2.0000e-04 (default) | positive scalar

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

ViaSpacing — Distance between vias

[0.0011 0.0070] (default) | two-element vector

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

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

Data Types: double

ViaDiameter — Diameter of via

5.0000e-04 (default) | positive scalar

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

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

Data Types: double

Height — Height of coplanar waveguide transmission line

0.0016 (default) | positive scalar

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

GroundPlaneWidth — Width of ground plane

0.0300 (default) | positive scalar

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

Example: cpgw = coplanarWaveguide(GroundPlaneWidth=0.0350)

Data Types: double

Substrate — Type of dielectric material

dielectric object

Type of dielectric material used as a substrate, specified as a dielectric object. The dielectric material in a coplanarWaveguide object with default properties is Teflon.

Example: d = dielectric("FR4"); cpgw = coplanarWaveguide(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 coplanarWaveguide object with default properties is PEC.

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

Data Types: string | char

IsShielded — Flag to add metal shielding

false or 0 (default) | true or 1

Flag to add a metal shielding to the PCB component, specified as a logical 0 or logical 1. The default value is logical 0.

Example: IsShielded = true or 1 add a metal shield.

Note

To enable FEM solver required for the metal shield property, download the Integro-Differential Modeling Framework for MATLAB. To download this add-on:

1. In the Home tab Environment section, click on Add-Ons. This opens the add-on explorer. You need an active internet connection to download the add-on.

2. Search for Integro-Differential Modeling Framework for MATLAB and click Install.

3. To verify if the download is successful, run

   matlab.addons.installedAddons

   in your MATLAB^® session command line.

4. On Windows, to run the IDMF add-on, you must install the Windows Subsystem for Linux (WSL). To install WSL, see Install Linux on Windows with WSL.

   The Windows Defender Firewall can block the PostgreSQL server when using the IDMF add-on. To resolve this issue, you can allow the server to communicate on desired networks if the firewall prompts. Alternatively, you can manually add the executable file of the PostgreSQL server located in <matlabroot>\sys\postgresql\win64\PostgreSQL\bin\postgres.exe. For more information, see https://support.microsoft.com/en-us/windows/risks-of-allowing-apps-through-windows-defender-firewall-654559af-3f54-3dcf-349f-71ccd90bcc5c.

Data Types: logical

Shielding — Metal shielding

shape.Box object

This property is read-only.

Metal shield for the PCB component, specified as a shape.Box object. The length and width of the box must be equal to the length and width of the ground plane. The center of the box is at [0 0 Shielding.Height].

Dependencies

To enable the Shielding property, set the IsShielded property to true or 1.

Connector — Type of RF connector

RFConnector object

Type of RF connector assembled at the feed locations of the PCB component, specified as a RFConnector object.

Example: Create connector from RFConnector object like this: coaxial = RFConnector adds a coaxial connector.

Dependencies

To enable the Connector property, set the IsShielded property to true or 1.

Object Functions

charge	Calculate and plot charge distribution
current	Calculate and plot current distribution
design	Design coplanar waveguide transmission line around particular frequency
feedCurrent	Calculate current at feed port
getZ0	Calculate characteristic impedance of transmission line
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
RFConnector	Create RF connector

Examples

Create Default Coplanar Waveguide

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]
          IsShielded: 0

View the coplanar waveguide transmission line.

show(waveguide)

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

sparam = sparameters(waveguide,1e9:0.3e9:10e9)

sparam = 
  sparameters with properties:

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

Plot the S-parameters.

rfplot(sparam)

Behavioral S-parameters of Coplanar Waveguide Transmission Line

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 impedance of 75 ohms.

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

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

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

References

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

Version History

Introduced in R2021b

R2023b: Metal shielding for coplanar waveguide

Use the IsShielded, Shielding, and Connector properties to add a metal shield to the coplanarWaveguide object.