filterStub

Create stub filter in microstrip form

Since R2022b

Description

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

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.

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.

Properties

PortLineLength — Length of input and output lines

0.0150 (default) | positive scalar

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

Example: filter = filterStub(PortLineLength=0.0014)

Data Types: double

PortLineWidth — Width of input and output lines

9e-4 (default) | positive scalar

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

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

Data Types: double

SeriesLineLength — Length of series line

0.0080 (default) | positive scalar | two-element vector

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

SeriesLineWidth — Width of series line

9e-4 (default) | positive scalar | two-element vector

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

StubLength — Length of stubs

[0.0083 0.0083] (default) | positive scalar | two-element vector

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

StubWidth — Width of stubs

[9e-04 9e-04] (default) | positive scalar | two-element vector

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

StubFeedOffsetX — X-offset from origin

[-0.0090 0.0090] (default) | positive scalar | two-element vector

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

StubDirection — Direction of stubs

[1 0] (default) | 1 | 0

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

StubShort — Flag to indicate short-circuited stubs

[0 0] (default) | 1 | 0

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 — Height of stub filter from ground plane

0.0016 (default) | positive scalar

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

GroundPlaneWidth — Width of ground plane

0.0200 (default) | positive scalar

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

Example: filter = filterStub(GroundPlaneWidth=0.0048)

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 filterStub object with default properties is Teflon.

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

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 filterStub object with default properties is PEC.

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

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
feedCurrent	Calculate current at feed port
getZ0	Calculate characteristic impedance of transmission line
layout	Plot all metal layers and board shape
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

Short-Circuited Stub Filter

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)

Multilayered Stub Filter

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);

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

R2023b: Metal shielding for stub filter

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