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stripLine

Create transmission line in strip form

Description

Use the stripLine object to create a transmission line in the strip form. Striplines are high speed transmission lines used for routing various RF components in the inner layers of a multi-layer printer circuit board (PCB). The structure consists of a transmission line trace surrounded by dielectric material suspended between two ground planes.

For the electromagnetic (EM) interactions between the ground planes, the feed is located in the middle of the strip and a via connects the top of the ground plane to the strip line.

Types and applications of stripline routing techniques:

  • Symmetric or Plain — Transmission lines routed on the internal layers

  • Asymmetric — Transmission lines not centrally embedded in the ground plane. Asymmetric striplines are placed closed to one of the ground planes. When routing signals the closer ground plane is used for reference for the stripline to ensure stronger return signal..

  • Edge-Coupled — Routing technique used for differential pairs. It has the same structure as the symmetric stripline routing but with trace spacing for the differential pair.

  • Broadside-Coupled — Routing technique used for differential pairs but stacked one on top of the other.

  • Suspended — Printed stripline with a strip conductor centered between two parallel ground planes, placed on a dielectric surface. The substrate is suspended in a metal closer. The major portion of the EM field is confined to the air gaps between dielectric substrates and ground planes

Creation

Description

example

strip = stripLine creates a default strip transmission line. The default dimensions are for a frequency range of 1 GHz to 5 GHz. The default transmission line lies in the X-Y plane.

example

strip = stripLine('propety1',value1,'property2',value2...) sets properties using one or more name value pair arguments. For example, strip = stripLine('Length',0.0300) creates a strip transmission line of length 0.0300 meters. Properties not specified retain their default values.

Properties

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

Example: strip = stripLine('Length',0.0300)

Data Types: double

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

Example: strip = stripLine('Width',0.0037)

Data Types: double

Height of the strip line in meters, specified as a positive scalar.

Example: strip = stripLine('Height',0.0026)

Data Types: double

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

Example: strip = stripLine('GroundPlaneWidth',0.0350)

Data Types: double

Type of dielectric material used as a substrate, specified as a dielectric object. The values of the default dielectric material are: ('Name',{'RT-Duriod'},'EpsilonR',2.2, 'LossTangent',0.001,'Thickness',0.0032) For more information see dielectric.

Example: d = dielectric('FR4'); strip = stripLine('Substrate',d)

Data Types: string | char

Type of metal used for conducting layers, specified as a metal object. For more information see metal.

Example: m = metal('PEC'); strip = stripLine('Conductor',m)

Data Types: string | char

Object Functions

chargeCalculate and plot charge distribution
currentCalculate and plot current distribution
designDesign symmetric strip transmission line around given frequency
feedCurrentCalculate current at feed port
getZ0Calculate characteristic impedance of transmission line
meshChange and view mesh properties of metal or dielectric in 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 transmission line in the form of a strip.

txstrip = stripLine
txstrip = 
  stripLine with properties:

              Length: 0.0202
               Width: 0.0027
              Height: 0.0016
    GroundPlaneWidth: 0.0150
           Substrate: [1×1 dielectric]
           Conductor: [1×1 metal]

show(txstrip)

Create a stripline transmission line of length 16.84 mm.

sline = stripLine('Length',16.84e-3);

View the transmission line.

show(sline)

Plot the s-parameters of the transmission line.

spar = sparameters(sline,linspace(1e9,3e9,11));
rfplot(spar);

More About

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Introduced in R2021b