txlineMicrostrip

Create microstrip transmission line

Description

Use the txlineMicrostrip object to create a microstrip transmission line. The cross-section of a microstrip transmission line is shown in this figure. The physical characteristics of the microstrip transmission line include the microstrip width (w), the microstrip thickness (t), the substrate height (d), and the relative permittivity constant (ε).

Creation

Syntax

txline = txlineMicrostrip

txline = txlineMicrostrip(Name,Value)

Description

txline = txlineMicrostrip creates a default microstrip transmission line object.

txline = txlineMicrostrip(Name,Value) sets Properties using one or more name-value pairs. For example, txline = txlineMicrostrip('Width',0.0046) creates a microstrip transmission line with a width of 0.0046 meters.

Properties

Name — Name of microstrip transmission line

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

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

Example: 'Name','microstrip1'

Example: txline.Name = 'microstrip1'

Data Types: char | string

LineLength — Physical length of microstrip transmission line

0.0100 (default) | positive scalar

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

Example: 'LineLength',0.0200

Example: txline.LineLength = 0.0200

Data Types: double

Width — Physical width of microstrip transmission line

0.0006 (default) | positive scalar

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

Example: 'Width',0.0008

Example: txline.Width = 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 of microstrip transmission line

0.000005 (default) | positive scalar

Physical thickness of the microstrip 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 nonegative 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

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 a positive scalar.

Data Types: double

Terminals — Terminals of microstrip transmission line

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

This property is read-only.

Terminals of the microstrip 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 and Group Delay of Microstrip Transmission Line

Create a microstrip transmission line using these specifications:

• Width - 0.08 mm

• Height - 1.6 mm

• Line length - 12.2777 mm

• Thickness - 10 mm

• Conductivity - 5.88e7 S/m

• EpsilonR - 3.9 F/m

microstriptxline = txlineMicrostrip('Width',0.08e-3,'Height',1.6e-3,...
    'LineLength',12.2777e-3,'Thickness',10e-6,'EpsilonR',3.9,'SigmaCond',5.88e7)

microstriptxline = 
  txlineMicrostrip: Microstrip element

           Name: 'Microstrip'
          Width: 8.0000e-05
         Height: 0.0016
      Thickness: 1.0000e-05
       EpsilonR: 3.9000
    LossTangent: 0
      SigmaCond: 58800000
     LineLength: 0.0123
    Termination: 'NotApplicable'
       StubMode: 'NotAStub'
       NumPorts: 2
      Terminals: {'p1+'  'p2+'  'p1-'  'p2-'}

Calculate the s-parameters of the transmission line at 10 GHz.

sparam = sparameters(microstriptxline,10e9,50);

Calculate the group delay of the transmission line at 10 GHz.

gd = groupdelay(microstriptxline,10e9,'Impedance',50)

gd = 4.2440e-11

Algorithms

• When you set the StubMode property to 'Shunt', the 2-port network consists of a stub transmission line that you can terminate with either a short circuit or an open circuit.

  

  Z_in is the input impedance of the shunt circuit. The ABCD-parameters for the shunt stub are calculated as:

  $$\begin{array}{c}A=1\\ B=0\\ C=1/Z_{in}\\ D=1\end{array}$$

  When you set the StubMode property to 'Series', the 2-port network consists of a series transmission line that you can terminate with either a short circuit or an open circuit.

  

  Z_in is the input impedance of the series circuit. The ABCD-parameters for the series stub are calculated as:

  $$\begin{array}{c}A=1\\ B=Z_{in}\\ C=0\\ D=1\end{array}$$