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coupledMicrostripLine

Create coupled microstrip transmission line

Since R2021b

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Description

Use the coupledMicrostripLine object to create a coupled microstrip transmission line. Coupled microstrip transmission lines are used to design directional couplers and filters. The combination of even and odd mode impedances determines the coupling ratio between the direct arm and the coupled arm.

Three part image from right to left: Default image of a coupled microstrip line. Current distribution on the microstrip line. S-parameters plot of the microstrip line.

To analyze the behavioral model for the coupled microstrip line, set the Behavioral property in the sparameters to true or 1.

Creation

Syntax

coupledmicrostrip = coupledMicrostripLine
coupledmicrostrip = coupledMicrostripLine(Name=Value)

Description

example

coupledmicrostrip = coupledMicrostripLine creates a default coupled microstrip transmission line with a Teflon substrate and default properties for a resonating frequency of 1.5 GHz.

example

coupledmicrostrip = coupledMicrostripLine(Name=Value) sets Properties using one or more name-value arguments. For example, coupledMicrostripLine(Length=0.0300) creates a coupled microstrip transmission line of length 0.0300 meters.

Properties

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

Example: coupledmicrostrip = coupledMicrostripLine(Length=0.0300)

Data Types: double

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

Example: coupledmicrostrip = coupledMicrostripLine(Width=0.0041)

Data Types: double

Distance between the direct arm and the coupled arm of the coupled microstrip transmission line, specified as a positive scalar in meters.

Example: coupledmicrostrip = coupledMicrostripLine(Spacing=0.00300)

Data Types: double

Height of the coupled microstrip line from the ground plane, specified as a positive scalar in meters. In the case of a multilayer substrate, use the Height property to create a coupled microstrip line at the interface of the two dielectrics.

Example: coupledmicrostrip = coupledMicrostripLine(Height=0.0023)

Data Types: double

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

Example: coupledmicrostrip = coupledMicrostripLine(GroundPlaneWidth=0.0400)

Data Types: double

Type of the dielectric material used as a substrate, specified as a dielectric object. The dielectric material in a coupledMicrostripLine object with default properties is Teflon. The thickness of the default dielectric material Teflon is 0.0016 m or the same as the Height property.

Example: d = dielectric("FR4"); coupledmicrostrip = coupledMicrostripLine(Substrate=d)

Data Types: string | char

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

Example: m = metal("PEC"); coupledmicrostrip =coupledMicrostripLine(Conductor=m)

Data Types: string | char

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 regarding firewalls, see Allowing apps through Windows Defender Firewall .

Data Types: logical

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]. You can modify the property after creating the object.

Dependencies

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

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

chargeCalculate and plot charge distribution
currentCalculate and plot current distribution
designDesign coupled microstrip transmission line around particular frequency
feedCurrentCalculate current at feed port
getZ0Calculate characteristic impedance of transmission line
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
RFConnectorCreate RF connector

Examples

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Open Live Script

Create a default coupled microstrip line. 

cml = coupledMicrostripLine
cml = 
  coupledMicrostripLine with properties:

              Length: 0.0271
               Width: 0.0051
             Spacing: 0.0046
              Height: 0.0016
    GroundPlaneWidth: 0.0300
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]
          IsShielded: 0

View the coupled microstrip line.

show(cml)

Open Live Script

Design and view a coupled microstrip line at the interface of a multilayer dielectric.

cml = design(coupledMicrostripLine,4e9,Z0e=75,Z0o=36);
cml.Substrate = dielectric(Name=["Teflon","Teflon"],EpsilonR=[2.1 2.1], ...
    LossTangent=[0 0],Thickness=[0.8e-3 0.8e-3]);
cml.Height = 0.8e-3;
show(cml)

Plot the current and charge distribution on the transmission line.

current(cml,4e9)

figure
charge(cml,4e9)

More About

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References

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

[2] “Microwaves101 | Coupled Line Couplers.” Accessed July 7, 2021. https://www.microwaves101.com/encyclopedias/coupled-line-couplers.

Version History

Introduced in R2021b

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See Also

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