txlineCPW

Create coplanar waveguide transmission line

Description

Use the txlineCPW object to create a coplanar waveguide transmission line. A cross-section of a coplanar waveguide transmission line is shown in this figure. The physical characteristics of the coplanar waveguide transmission line include the conductor width (w), the conductor thickness (t), the slot width (s), the substrate height (d), and the permittivity constant (ε).

Creation

Syntax

txline = txlineCPW

txline = txlineCPW(Name,Value)

Description

txline = txlineCPW creates a default coplanar waveguide transmission line object.

txline = txlineCPW(Name,Value) sets Properties using one or more name-value pairs. For example, txline = txlineCPW('SlotWidth',0.0046) creates a coplanar waveguide transmission line with a slot width of 0.0046 meters.

Properties

Name — Name of coplanar waveguide transmission line

'cpw' (default) | string scalar | character vector

Name of the coplanar waveguide transmission line, specified as a string scalar or a character vector.

Example: 'Name','cpw1'

Example: txline.Name = 'cpw1'

Data Types: char | string

ConductorWidth — Physical width

0.0006 (default) | positive scalar

Physical width of the conductor, specified as a positive scalar in meters.

Example: 'ConductorWidth',0.0200

Example: txline.ConductorWidth = 0.0200

Data Types: double

SlotWidth — Physical width of slot

0.0002 (default) | positive scalar

Physical width of the slot, specified as a positive scalar in meters.

Example: 'SlotWidth',0.0008

Example: txline.SlotWidth = 0.0008

Data Types: double

Height — Physical height of conductor or dielectric thickness

0.000635 (default) | positive scalar

Physical height of the conductor or dielectric thickness, specified as a positive scalar in meters.

Example: 'Height',0.000835

Example: txline.Height = 0.000835

Data Types: double

Thickness — Physical thickness

0.000005 (default) | positive scalar

Physical thickness of the transmission line, specified as a positive scalar in meters.

Example: 'Thickness',0.000008

Example: txline Thickness = 0.000008

Data Types: double

EpsilonR — Relative permittivity of dielectric

9.8 (default) | positive scalar

Relative permittivity of the dielectric, specified as a positive scalar.

Example: 'EpsilonR',8.8

Example: txline.EpsilonR = 8.8

Data Types: double

LossTangent — Loss angle tangent of dielectric

0 (default) | nonnegative scalar

Loss angle tangent of the dielectric, specified as a nonnegative scalar.

Example: 'LossTangent',1

Example: txline.LossTangent = 1

Data Types: double

SigmaCond — Conductivity of conductor

Inf (default) | nonnegative scalar

Conductivity of the conductor, specified as a nonnegative scalar in Siemens per meter (S/m).

Example: 'SigmaCond',2

Example: txline.SigmaCond = 2

Data Types: double

LineLength — Physical length

0.0100 (default) | positive scalar

Physical length of the transmission line, specified as a positive scalar in meters.

Example: 'LineLength',0.0200

Example: txline.LineLength = 0.0200

Data Types: double

Termination — Stub transmission line termination

'NotApplicable' (default) | 'Open' | 'Short'

Stub transmission line termination, specified as 'NotApplicable', 'Open', or 'Short'.

Example: 'Termination','Short'

Example: txline.Termination = 'Short'

Data Types: char

StubMode — Type of stub

'NotAStub' (default) | 'Series' | 'Shunt'

Type of stub, specified as 'NotAStub', 'Series', or 'Shunt'.

Example: 'StubMode','Series'

Example: txline.StubMode = 'Series'

Data Types: char

NumPorts — Number of input and output ports

2 (default) | positive scalar

This property is read-only.

Number of input and output ports, returned as positive scalar.

Data Types: double

Terminals — Terminals of coplanar waveguide transmission line

{'p1+' p2+' 'p1-' 'p2-'} (default) | cell array of strings

This property is read-only.

Terminals of the coplanar waveguide transmission line, returned as a cell array of strings.

Data Types: char | string

Object Functions

sparameters	S-parameter object
groupdelay	Group delay of S-parameter object or RF filter object or RF Toolbox circuit object
noisefigure	Calculate noise figure of transmission lines, series RLC, and shunt RLC circuits
getZ0	Calculate characteristic impedance of transmission line object
circuit	Circuit object
clone	Create copy of existing circuit element or circuit object

Examples

S-Parameters of Coplanar Waveguide Transmission Line

Create a coplanar waveguide transmission line using these specifications:

• Conductor width : 45 mu m

• Slot width : 50 mu m

• Height of substrate : 525 mu m

• Thickness : 1 mu m

• GaAS permittivity or Epsilon R : 2.5 F/m

• Conductivity : 3.33e7 S/m

cpwtxline = txlineCPW('ConductorWidth',45e-6,'SlotWidth',50e-6,'Height',525e-6,...
    'Thickness',1e-6,'EpsilonR',2.5,'SigmaCond',3.33e7)

cpwtxline = 
  txlineCPW: CPW element

              Name: 'CPW'
    ConductorWidth: 4.5000e-05
         SlotWidth: 5.0000e-05
            Height: 5.2500e-04
         Thickness: 1.0000e-06
          EpsilonR: 2.5000
       LossTangent: 0
         SigmaCond: 33300000
        LineLength: 0.0100
       Termination: 'NotApplicable'
          StubMode: 'NotAStub'
          NumPorts: 2
         Terminals: {'p1+'  'p2+'  'p1-'  'p2-'}

Calculate the S-parameters of the transmission line at 20 GHz.

sparam = sparameters(cpwtxline,20e9);