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filterStub

Create stub filter in microstrip form

Since R2022b

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Description

Use the filterStub object to create a stub filter in the microstrip form.

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

Creation

Syntax

filter = filterStub
filter = filterStub(Name=Value)

Description

filter = filterStub creates a default stub with default property values for a passband frequency centered around 2 GHz.

example

filter = filterStub(Name=Value) sets Properties using one or more name-value arguments. For example, filterStub(PortLineLength=9e-4) creates a stub filter with a port line length of 9e-4 meters. Properties not specified retain their original values.

example

Properties

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Length of the input and output lines in meters, specified as a positive scalar.

Example: filter = filterStub(PortLineLength=0.0014)

Data Types: double

Width of the input and output lines in meters, specified as a positive scalar.

Example: filter = filterStub(PortLineWidth=8e-4)

Data Types: double

Length of the series line in meters, specified as a positive scalar or a two-element vector.

Example: filter = filterStub(SeriesLineLength=0.0070)

Data Types: double

Width of the series line in meters, specified as a positive scalar or a two-element vector.

Example: filter = filterStub(SeriesLineWidth=8e-4)

Data Types: double

Length of the stubs in meters, specified as a positive scalar or a two-element vector.

Example: filter = filterStub(StubLength=[0.0078 0.0078])

Data Types: double

Width of the stubs in meters, specified as a positive scalar or a two-element vector.

Example: filter = filterStub(StubWidth=[0.0078 0.0078])

Data Types: double

X-offset from the origin in meters, specified as a positive scalar or a two-element vector.

Example: filter = filterStub(StubFeedOffsetX=0.0087)

Data Types: double

Direction of the stubs, specified as a two-element vector of:

  • 1 — Indicates that the stub points to the top.

  • 0 — Indicates that the stub points to the bottom.

Example: filter = filterStub(StubDirection=[0 1])

Data Types: double

Flag to indicate short-circuited stubs, specified as a two-element vector of:

  • 1 — Indicates stub is short-circuited.

  • 0 — Indicates stub is open-circuited.

Example: filter = filterStub(StubShort=[1 1])

Data Types: double

Height of the stub filter from the ground plane in meters, specified as a positive scalar. For multilayer dielectrics, use the Height property to create the filter between the two dielectric layers.

Example: filter = filterStub(Height=0.0028)

Data Types: double

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

Example: filter = filterStub(GroundPlaneWidth=0.0048)

Data Types: double

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

Example: d = dielectric("FR4"); filter = filterStub(Substrate=d)

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

Example: m = metal("Copper"); filter = filterStub(Conductor=m)

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

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.

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
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 short-circuited stub filter. 

filter = filterStub(StubShort=[1 1])
filter = 
  filterStub with properties:

      PortLineLength: 0.0150
       PortLineWidth: 9.0000e-04
    SeriesLineLength: 0.0080
     SeriesLineWidth: 9.0000e-04
          StubLength: [0.0083 0.0083]
           StubWidth: [9.0000e-04 9.0000e-04]
         StubOffsetX: [-0.0090 0.0090]
       StubDirection: [1 0]
           StubShort: [1 1]
              Height: 0.0016
    GroundPlaneWidth: 0.0200
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]
          IsShielded: 0

Visualize the filter.

show(filter)

Figure contains an axes object. The axes object with title filterStub element, xlabel x (mm), ylabel y (mm) contains 8 objects of type patch, surface. These objects represent PEC, feed, Teflon.

Open Live Script

Create a multilayered dielectric stub filter.

filter = filterStub;
filter.Substrate = dielectric(Name={'Teflon','Teflon'},EpsilonR=[2.1 2.1], ...
    LossTangent=[0 0],Thickness=[0.8e-3 0.8e-3]);
filter.Height = 0.8e-3;

Visualize the filter.

show(filter);

Figure contains an axes object. The axes object with title filterStub element, xlabel x (mm), ylabel y (mm) contains 7 objects of type patch, surface. These objects represent PEC, feed, Teflon.

References

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

[2] Wen-Hua Tu and Kai Chang. “Compact Microstrip Bandstop Filter Using Open Stub and Spurline.” IEEE Microwave and Wireless Components Letters 15, no. 4 (April 2005): 268–70. https://doi.org/10.1109/LMWC.2005.845739.

Version History

Introduced in R2022b

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See Also

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