filterCoupledLine

Create coupled line filter in microstrip form

Since R2021b

Description

Use the filterCoupledLine object to create a coupled line filter in microstrip form. The filter structure consists of open-circuited coupled microstrip lines. You can control the bandwidth of the filter by varying the filter order, width, and distance between the coupled lines.

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

Creation

Syntax

filter = filterCoupledLine

filter = filterCoupledLine(Name=Value)

Description

filter = filterCoupledLine creates a default coupled line filter with default passband of the filter centered around 2 GHz.

filter = filterCoupledLine(Name=Value) sets Properties using one or more name-value arguments. For example, filterCoupledLine(FilterOrder=5) creates a fifth-order coupled line filter. Properties not specified retain their default values.

Properties

FilterOrder — Filter order

3 (default) | positive scalar

Filter order, specified as a positive scalar.

Example: filter = filterCoupledLine(FilterOrder=5)

Data Types: double

PortLineLength — Length of input and output lines

0.0279 (default) | positive scalar

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

Example: filter = filterCoupledLine(PortLineLength=0.0553)

Data Types: double

PortLineWidth — Width of input and output lines

0.0051 (default) | positive scalar

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

Example: filter = filterCoupledLine(PortLineWidth=0.0087)

Data Types: double

CoupledLineLength — Lengths of coupled lines

[0.0279 0.0279 0.0279 0.0279] (default) | vector

Lengths of the coupled lines in meters, specified as a vector of positive elements.

Example: filter = filterCoupledLine(CoupledLineLength=[0.0553 0.0553 0.0553 0.0553])

Data Types: double

CoupledLineWidth — Widths of coupled lines

[0.0036 0.0049 0.0049 0.0036] (default) | vector

Widths of the coupled lines in meters, specified as a vector of positive elements.

Example: filter = filterCoupledLine(CoupledLineWidth=[0.0046 0.0059 0.0059 0.0046])

Data Types: double

CoupledLineSpacing — Distance between coupled lines

[1.8270e-04 0.0019 0.0019 1.8270e-04] (default) | vector

Distance between the coupled lines in meters, specified as a vector of positive elements.

Example: filter = filterCoupledLine(CoupledLineSpacing=[2.8270e-04 0.0020 0.0020 2.8270e-04])

Data Types: double

Height — Height of coupled line filter from ground plane

0.0016 (default) | positive scalar

Height of the coupled line 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 = filterCoupledLine(Height=0.0028)

Data Types: double

GroundPlaneWidth — Width of ground plane

0.0551 (default) | positive scalar

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

Example: filter = filterCoupledLine(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 filterCoupledLine object with default properties is Teflon. The thickness of the default dielectric material Teflon is 0.0016 m.

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

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

Data Types: string | char

Object Functions

charge	Calculate and plot charge distribution
current	Calculate and plot current distribution
design	Design coupled line filter around specified frequency
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

Examples

Create Default Coupled Line Filter

Create and view a default coupled line filter.

coupledfilter = filterCoupledLine

coupledfilter = 
  filterCoupledLine with properties:

           FilterOrder: 3
        PortLineLength: 0.0279
         PortLineWidth: 0.0051
     CoupledLineLength: [0.0279 0.0279 0.0279 0.0279]
      CoupledLineWidth: [0.0036 0.0049 0.0049 0.0036]
    CoupledLineSpacing: [1.8270e-04 0.0019 0.0019 1.8270e-04]
                Height: 0.0016
      GroundPlaneWidth: 0.0551
             Substrate: [1x1 dielectric]
             Conductor: [1x1 metal]
            IsShielded: 0

show(coupledfilter)

Coupled Line Filter at Specified Frequency

Create and view a coupled line filter at 3 GHz.

coupledfilter = design(filterCoupledLine,3e9)

coupledfilter = 
  filterCoupledLine with properties:

           FilterOrder: 3
        PortLineLength: 0.0372
         PortLineWidth: 0.0051
     CoupledLineLength: [0.0186 0.0186 0.0186 0.0186]
      CoupledLineWidth: [0.0036 0.0049 0.0049 0.0036]
    CoupledLineSpacing: [1.8270e-04 0.0019 0.0019 1.8270e-04]
                Height: 0.0016
      GroundPlaneWidth: 0.0551
             Substrate: [1x1 dielectric]
             Conductor: [1x1 metal]
            IsShielded: 0

show(coupledfilter)

Fifth-Order Coupled Line Chebyshev Filter

Design and view a fifth-order coupled-line Chebyshev filter at 3 GHz with a ripple factor of 0.5 dB.

coupledfilter = filterCoupledLine(FilterOrder=5);
coupledfilter = design(coupledfilter,3e9,FilterType="Chebyshev",RippleFactor=0.5);
show(coupledfilter)

Plot the current and charge distribution of this filter at 3 GHz.

figure
current(coupledfilter,3e9)

figure
charge(coupledfilter,3e9)

References

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

[2] Ragani, Taoufik, N. Amar Touhami, and M. Agoutane. “Designing a Microstrip Coupled Line Bandpass Filter.” International Journal of Engineering & Technology 2, no. 4 (September 6, 2013): 266. https://doi.org/10.14419/ijet.v2i4.1173.

Version History

Introduced in R2021b

R2023b: Behavioral Analysis for Coupled Line Filter

Use the sparameters function and the pcbElement object to perform the behavioral analysis of a coupled line filter.