txlineTwoWire

Create two-wire transmission line

Description

Use the txlineTwoWire object to create a two-wire transmission line. A cross-section of a two-wire transmission line is shown in this figure. The physical characteristics of a two-wire transmission line include the radii of the conducting wires, the separation or physical distance between the wire centers, and the relative permittivity and permeability of the wires. RF Toolbox™ software assumes that the relative permittivity and permeability are uniform.

Creation

Syntax

twowiretxline = txlineTwoWire

twowiretxline = txlineTwoWire(Name,Value)

Description

twowiretxline = txlineTwoWire creates a default two-wire transmission line object.

twowiretxline = txlineTwoWire(Name,Value) sets Properties using one or more name-value pairs. For example, txline = txlineTwoWire('Separation',0.0046) creates a two-wire transmission line with a dielectric thickness of 0.0046 meters.

Properties

Name — Name of two-wire transmission line

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

Name of the two-wire transmission line, specified as a string scalar or a character vector.

Example: 'Name','twowire1'

Example: twowiretxline.Name = 'twowire1'

Data Types: char | string

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: twowiretxline.LineLength = 0.0200

Data Types: double

Radius — Conducting wire radius

0.000670 (default) | positive scalar

Conducting wire radius in the two-wire transmission line, specified as a positive scalar in meters.

Example: 'Radius',0.000970

Example: twowiretxline.Radius = 0.000970

Data Types: double

Separation — Thickness of dielectric

0.0016 (default) | positive scalar

Thickness of the dielectric, specified as a positive scalar in meters.

Example: 'Separation',0.0025

Example: twowiretxline.Separation = 0.0025

Data Types: double

MuR — Relative permeability of dielectric

1 (default) | positive scalar

Relative permeability of the dielectric, specified as a positive scalar. Relative permeability of the dielectric, μ, to the permeability in free space, μ₀.

Example: 'MuR',1.5

Example: twowiretxline.MuR = 1.5

Data Types: double

EpsilonR — Relative permittivity of dielectric

2.3 (default) | positive scalar

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

Example: 'EpsilonR',3.3

Example: twowiretxline.EpsilonR = 3.3

Data Types: double

LossTangent — Loss angle tangent of dielectric

0 (default) | nonnegative scalar

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

Example: 'LossTangent',1

Example: twowiretxline.LossTangent = 1

Data Types: double

SigmaCond — Conductivity of conductor

Inf (default) | scalar

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

Example: 'SigmaCond',2

Example: twowiretxline.SigmaCond = 2

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: twowiretxline.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: twowiretxline.StubMode = 'Series'

Data Types: char

NumPorts — Number of input and output ports

Read-only: 2 (default) | positive scalar

This property is read-only.

Number of input and output ports, specified as a positive scalar.

Data Types: double

Terminals — Terminals of coaxial transmission line

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

This property is read-only.

Terminals of coaxial transmission line, specified as a cell array of strings.

Data Types: char | string

Object Functions

sparameters	Calculate S-parameters for RF data, network, circuit, and matching network objects
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 with and without dispersion for transmission line
circuit	Circuit object
clone	Create copy of existing circuit element or circuit object

Examples

Group Delay and Noise Figure of Two-Wire Transmission Line

Create a two-wire transmission line using these specifications:

• Radius - 0.5 mm

• Dielectric - air

• Thickness of dielectric or separation - 1.088 mm

• Permittivity or EpsilonR - 1.0054

twowiretxline = txlineTwoWire('Radius',0.5e-3,'EpsilonR',1.0054,'Separation',1.088e-3);

Calculate the noise figure and the group delay of the transmission line at 2.5 GHz.

nf = noisefigure(twowiretxline,2.5e9)

nf = 
0

gd = groupdelay(twowiretxline,2.5e9)

gd = 
3.3446e-11

Version History

Introduced in R2020b

R2023b: Recommended over rfckt.twowire

txlineTwoWire is recommended over rfckt.twowire because it enables you to:

• Create a two-wire transmission line.

• Build a circuit object with a two-wire transmission line.

• Model a two-wire transmission line element in an RF chain created using an rfbudget object or the RF Budget Analyzer app, and then export this element to RF Blockset™ or to rfsystem System object™ for circuit envelope analysis.