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filterCoupledLine

Create coupled line filter in microstrip form

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.

Creation

Description

example

filter = filterCoupledLine creates a default coupled line filter using a Teflon substrate. The default passband of the filter is centered around 2 GHz.

example

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

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Filter order, specified as a positive scalar.

Example: filter = filterCoupledLine(FilterOrder=5)

Data Types: double

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

Example: filter = filterCoupledLine(PortLineLength=0.0553)

Data Types: double

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

Example: filter = filterCoupledLine(PortLineWidth=0.0087)

Data Types: double

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

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

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 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

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

Example: filter = filterCoupledLine(GroundPlaneWidth=0.0048)

Data Types: double

Type of dielectric material used as a substrate, specified as a dielectric object. The thickness of the default dielectric material Teflon is 0.0016 m.

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

Data Types: string | char

Type of metal used in the conducting layers, specified as a metal object.

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

Data Types: string | char

Object Functions

chargeCalculate and plot charge distribution
currentCalculate and plot current distribution
designDesign coupled line filter around specified 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

Examples

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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]

show(coupledfilter)

Figure contains an axes object. The axes object with title filterCoupledLine element contains 6 objects of type patch, surface. These objects represent PEC, feed, Teflon.

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]

show(coupledfilter)

Figure contains an axes object. The axes object with title filterCoupledLine element contains 6 objects of type patch, surface. These objects represent PEC, feed, Teflon.

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)

Figure contains an axes object. The axes object with title filterCoupledLine element contains 6 objects of type patch, surface. These objects represent PEC, feed, Teflon.

Plot the current and charge distribution of this filter at 5 GHz.

figure
current(coupledfilter,5e9)

Figure contains an axes object. The axes object with title Current distribution contains 4 objects of type patch.

figure
charge(coupledfilter,5e9)

Figure contains an axes object. The axes object with title Charge distribution contains 4 objects of type patch.

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