txlineMicrostrip

Create microstrip transmission line

Since R2020b. Recommended over rfckt.microstrip.

Description

Use the txlineMicrostrip object to create a standard, embedded, inverted, or suspended microstrip transmission line. This figure shows the cross sections of the four types of microstrip transmission lines you can create using the txlineMircostrip object. The physical characteristics of the microstrip transmission line include the conductor width (w), the conductor thickness (t), the dielectric thickness (d), the relative permittivity constant (ε), and the height of the conductor above the ground plane (h).

Microstrip transmission line types: standard. embedded, inverted, and suspended.

Creation

Syntax

txline = txlineMicrostrip

txline = txlineMicrostrip(Name,Value)

Description

txline = txlineMicrostrip creates a standard 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 standard microstrip transmission line with a width of 0.0046 meters.

example

Properties

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`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

`Type` — Type of microstrip transmission line
`'Standard'` (default) | `'Embedded'` | `'Inverted'` | `'Suspended'`

Type of microstrip transmission line, specified as one of the following:

'Standard' — Standard microstrip transmission line
'Embedded' — Embedded microstrip transmission line
'Inverted' — Inverted microstrip transmission line
'Suspended' — Suspended microstrip transmission line

Note

When you create a default txlineMicrostrip object or set the Type property to 'Standard', the Type property does not show in MATLAB^®.

Example: 'Type','Embedded'

Example: txline.Type = 'Embedded'

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
`0.000635` (default) | positive scalar

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

Example: 'Height',0.000835

Example: txline.Height = 0.000835

Data Types: double

`DielectricThickness` — Dielectric thickness of microstrip transmission line
positive scalar

Dielectric thickness of the inverted, embedded, or suspended microstrip transmission line, specified as a positive scalar in meters. Default values of dielectric thickness for the embedded, inverted, and suspended microstrip transmission lines are is listed in the table.

Type of Microstrip	Default value of `DielctricThickness`
`'Embedded'`	`Height`*2
`'Inverted'`	`Height`
`'Suspended'`	`Height`/2

Note

When you create a standard microstrip transmission line, the DielectricThickness property does not show in MATLAB.
By default txlineMicrostrip object sets the dielectric thickness of the standard microstrip transmission line to the value of the Height.

Example: 'DielectricThickness',0.0012

Example: txline.DielectricThickness = 0.0012

Dependencies

To enable this property, set Type as 'Embedded' or 'Inverted', or 'Suspended'.

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. You can now model microstrip with thickness set to 0 mm.

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`	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

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S-Parameters and Group Delay of Microstrip Transmission Line

Open Live Script

Create a microstrip transmission line using these specifications:

Width: 0.08 mm
Height: 1.6 mm
Line length: 12.2777 mm
Thickness: 10e-6 m
Conductivity: 5.88e7 S/m
Relative permittivity of the dielectric: 3.9

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

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

S-Parameters and Characteristic Impedance of Suspended Microstrip Line

This example uses:

Open Live Script

This example uses RF PCB Toolbox to calculate electromagnetic (EM) solver S-parameters of the microstrip line.

Create Suspended Microstrip Line

Create a suspended microstrip transmission line with a copper conductor and Teflon substrate.

tx = txlineMicrostrip('Type','Suspended',...
    'LineLength',0.04705,'Width',3.5e-3,...
    'Height',1.6e-3,"DielectricThickness",0.8e-3,...
    "EpsilonR",2.1,"LossTangent",0.2e-3,...
    'SigmaCond',596e5,"Thickness",3.556e-5,...
    "StubMode","NotAStub","Termination","NotApplicable");

Behavioral Modeling

Calculate and plot the S-parameters with the reference impedance of 50 $Ω$ .

freq = (1:40)*100e6;
Srf = sparameters(tx,freq,50);
rfplot(Srf)

$Figure contains an axes object. The axes object with xlabel Frequency (GHz), ylabel Magnitude (dB) contains 4 objects of type line. These objects represent dB(S_{11}), dB(S_{21}), dB(S_{12}), dB(S_{22}).$

Calculate the characteristic impedance.

Zc_rf = getZ0(tx)

Zc_rf = 
75.0279

EM Modeling

Input the microstrip transmission line to the microstripLine object from the RF PCB Toolbox for EM modeling.

tx_em = microstripLine(tx)

tx_em = 
  microstripLine with properties:

              Length: 0.0471
               Width: 0.0035
              Height: 0.0016
    GroundPlaneWidth: 0.0175
           Substrate: [1x1 dielectric]
           Conductor: [1x1 metal]
          IsShielded: 0

View the suspended microstrip transmission line.

show(tx_em)

Figure contains an axes object. The axes object with title microstripLine element, xlabel x (mm), ylabel y (mm) contains 7 objects of type patch, surface. These objects represent Conductor1, feed, Substrate1.

Calculate and plot the S-parameters using EM solver from RF PCB Toolbox.

Sem = sparameters(tx_em,freq,50);
rfplot(Sem)

Zc_em = getZ0(tx_em)

Zc_em = 
72.9110 - 0.2262i

S-Parameters for Inverted Microstrip Transmission Line

This example uses:

Open Live Script

Select the dielectric and metal layers for an inverted microstrip transmission line from the dielectric and metal libraries, respectively, of the RF PCB Toolbox.

dFR4 = dielectric('FR4');
dFR4.Thickness = 3.2e-4;
mCopper = metal('Copper');

Create an inverted microstrip transmission line with a copper conductor and an FR4 substrate at 6 GHz with the line length of 0.5 $λ$ and the reference impedance of 75 $Ω$ . The air to substrate thickness ratio is calculated using:

$\frac{Thickness of air layer}{Thickness of substrate} = \frac{12.8 e - 4}{3.2 e - 4} = 4$

prototype_behavioral = txlineMicrostrip('Type','Inverted',...
    'DielectricThickness',dFR4.Thickness,"EpsilonR",dFR4.EpsilonR, ...
    'Height',12.8e-4,"LossTangent",dFR4.LossTangent, ...
    "SigmaCond",mCopper.Conductivity,"Thickness",mCopper.Thickness);

Input the inverted microstrip transmission line to the microstripLine object from the RF PCB Toolbox for EM modeling.

prototype_em = microstripLine(prototype_behavioral);

Use the design (Antenna Toolbox) function to design the microstripLine (RF PCB Toolbox) object at 6 GHz with the line length of 0.5 $λ$ and reference impedance of 75 $Ω$ .

tx = design(prototype_em,6e9,'Z0',75,'LineLength',0.5);

View the microstipLine object.

show(tx)

Plot S-Parameters

Calculate and plot the behavioral and electromagnetic (EM) solver modeled S-parameters of the line with the reference impedance of 50 $Ω$ . Use the Behavioral name-value argument of the sparameters (RF PCB Toolbox) function to compute the behavioral S-parameters.

freq = (1:5:66)*100e6;
Srf = sparameters(tx,freq,50,'Behavioral',true);
Sem = sparameters(tx,freq,50);
rfplot(Srf,'-s','db')
hold on
rfplot(Sem,'-x','db')
title('Behavioral vs. EM solver modeled S-parameters');

$Figure contains an axes object. The axes object with title Behavioral vs. EM solver modeled S-parameters, xlabel Frequency (GHz), ylabel Magnitude (dB) contains 8 objects of type line. These objects represent dB(S_{11}), dB(S_{21}), dB(S_{12}), dB(S_{22}).$

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:

$\begin{matrix} A = 1 \\ B = 0 \\ C = 1 / Z_{i n} \\ D = 1 \end{matrix}$
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:

$\begin{matrix} A = 1 \\ B = Z_{i n} \\ C = 0 \\ D = 1 \end{matrix}$

References

[1] Garg, Ramesh, I. J. Bahl, and Maurizio Bozzi. Microstrip Lines and Slotlines. 3rd ed. Artech House Microwave Library. Boston: Artech House, 2013.

[2] Wadell, Brian C. Transmission Line Design Handbook. The Artech House Microwave Library. Boston: Artech House, 1991.

Version History

Introduced in R2020b

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R2023b: Recommended over `rfckt.microstrip`

txlineMicrostrip is recommended over rfckt.microstrip because it enables you to:

Create a standard, embedded, inverted, or suspended microstrip transmission line.
Build a circuit object with a standard, embedded, inverted, or suspended microstrip transmission line.
Input the txlineMicrostrip object to the microstripLine object from RF PCB Toolbox™ for EM modeling.
Model a standard, embedded, inverted, or suspended microstrip 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.

txlineMicrostrip

Description

Creation

Syntax

Description

Properties

`Name` — Name of microstrip transmission line
`'Microstrip'` (default) | string scalar | character vector

`Type` — Type of microstrip transmission line
`'Standard'` (default) | `'Embedded'` | `'Inverted'` | `'Suspended'`

`LineLength` — Physical length of microstrip transmission line
`0.0100` (default) | positive scalar

`Width` — Physical width of microstrip transmission line
`0.0006` (default) | positive scalar

`Height` — Physical height of conductor
`0.000635` (default) | positive scalar

`DielectricThickness` — Dielectric thickness of microstrip transmission line
positive scalar

Dependencies

`Thickness` — Physical thickness of microstrip transmission line
`0.000005` (default) | positive scalar

`EpsilonR` — Relative permittivity of dielectric
`9.8` (default) | positive scalar

`LossTangent` — Loss angle tangent of dielectric
`0` (default) | nonnegative scalar

`SigmaCond` — Conductivity of conductor
`Inf` (default) | nonnegative scalar

`Termination` — Stub transmission line termination
`'NotApplicable'` (default) | `'Open'` | `'Short'`

`StubMode` — Type of stub
`'NotAStub'` (default) | `'Series'` | `'Shunt'`

`NumPorts` — Number of input and output ports
`2` (default) | positive scalar

`Terminals` — Terminals of microstrip transmission line
`{'p1+' p2+' 'p1-' 'p2-'}` (default) | cell array of strings

Object Functions

Examples

S-Parameters and Group Delay of Microstrip Transmission Line

S-Parameters and Characteristic Impedance of Suspended Microstrip Line

S-Parameters for Inverted Microstrip Transmission Line

Algorithms

References

Version History

R2023b: Recommended over `rfckt.microstrip`

See Also

Topics

txlineMicrostrip

Description

Creation

Syntax

Description

Properties

Name — Name of microstrip transmission line 'Microstrip' (default) | string scalar | character vector

Type — Type of microstrip transmission line 'Standard' (default) | 'Embedded' | 'Inverted' | 'Suspended'

LineLength — Physical length of microstrip transmission line 0.0100 (default) | positive scalar

Width — Physical width of microstrip transmission line 0.0006 (default) | positive scalar

Height — Physical height of conductor 0.000635 (default) | positive scalar

DielectricThickness — Dielectric thickness of microstrip transmission line positive scalar

Dependencies

Thickness — Physical thickness of microstrip transmission line 0.000005 (default) | positive scalar

EpsilonR — Relative permittivity of dielectric 9.8 (default) | positive scalar

LossTangent — Loss angle tangent of dielectric 0 (default) | nonnegative scalar

SigmaCond — Conductivity of conductor Inf (default) | nonnegative scalar

Termination — Stub transmission line termination 'NotApplicable' (default) | 'Open' | 'Short'

StubMode — Type of stub 'NotAStub' (default) | 'Series' | 'Shunt'

NumPorts — Number of input and output ports 2 (default) | positive scalar

Terminals — Terminals of microstrip transmission line {'p1+' p2+' 'p1-' 'p2-'} (default) | cell array of strings

Object Functions

Examples

S-Parameters and Group Delay of Microstrip Transmission Line

S-Parameters and Characteristic Impedance of Suspended Microstrip Line

S-Parameters for Inverted Microstrip Transmission Line

Algorithms

References

Version History

R2023b: Recommended over rfckt.microstrip

See Also

Topics

`Name` — Name of microstrip transmission line
`'Microstrip'` (default) | string scalar | character vector

`Type` — Type of microstrip transmission line
`'Standard'` (default) | `'Embedded'` | `'Inverted'` | `'Suspended'`

`LineLength` — Physical length of microstrip transmission line
`0.0100` (default) | positive scalar

`Width` — Physical width of microstrip transmission line
`0.0006` (default) | positive scalar

`Height` — Physical height of conductor
`0.000635` (default) | positive scalar

`DielectricThickness` — Dielectric thickness of microstrip transmission line
positive scalar

`Thickness` — Physical thickness of microstrip transmission line
`0.000005` (default) | positive scalar

`EpsilonR` — Relative permittivity of dielectric
`9.8` (default) | positive scalar

`LossTangent` — Loss angle tangent of dielectric
`0` (default) | nonnegative scalar

`SigmaCond` — Conductivity of conductor
`Inf` (default) | nonnegative scalar

`Termination` — Stub transmission line termination
`'NotApplicable'` (default) | `'Open'` | `'Short'`

`StubMode` — Type of stub
`'NotAStub'` (default) | `'Series'` | `'Shunt'`

`NumPorts` — Number of input and output ports
`2` (default) | positive scalar

`Terminals` — Terminals of microstrip transmission line
`{'p1+' p2+' 'p1-' 'p2-'}` (default) | cell array of strings

R2023b: Recommended over `rfckt.microstrip`