rfckt.microstrip

Microstrip transmission line

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Description

Use themicrostripclass to represent microstrip transmission lines characterized by line dimensions and optional stub properties.

A microstrip transmission line is shown in cross-section in the following figure. Its physical characteristics include the microstrip width (w), the microstrip thickness (t), the substrate height (d), and the relative permittivity constant (ε).

microstrip transmission line

Creation

Syntax

h = rfckt.microstrip

h = rfckt.microstrip(Name,Value)

Description

example

h = rfckt.microstripreturns a microstrip transmission line object whose properties are set to their default values.

h = rfckt.microstrip(Name,Value)sets properties using one or more name-value pairs. For example,rfckt.microstrip('Thickness',0.0075e-6)creates a microstrip transmission line with thickness of0.0075e-6meters. You can specify multiple name-value pairs. Enclose each property name in a quote. Properties not specified retain their default values.

Properties

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`AnalyzedResult`—Computed S-parameters, noise figure, OIP3, and group delay values
`rfdata.data`object

Computed S-parameters, noise figure, OIP3, and group delay values, specified asrfdata.dataobject.AnalyzedResultis a read-only property. For more information refer,Algorithms.

Data Types:function_handle

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

Relative permittivity of dielectric, specified as a scalar. The relative permittivity is the ratio of permittivity of the dielectric, $ε$ , to the permittivity in free space, $ε_{0}$ .

Data Types:double

`Height`—Dielectric thickness or physical height of conductor
`6.35e-4`(default) |scalar

Dielectric thickness or physical height of the conductor, specified as a scalar in meters.

Data Types:double

`LineLength`—Physical length of transmission
`0.01`(default) |scalar

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

Data Types:double

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

Loss angle tangent of dielectric, specified as a scalar.

Data Types:double

`Name`—Object name
`'Microstrip Transmission Line'`(default) |`1-by-N`character array|string scalar

This property is read-only.

Object name, specified as an1-by-Ncharacter array or string scalar.

Data Types:char

`nport`—Number of ports
`2`(default) |positive integer

数量的端口,指定为一个positive integer.nportt is a read-only property.

Data Types:double

`SigmaCond`—Conductor conductivity
`Inf`(default) |scalar

Conductor conductivity, specified as a scalar in Siemens per meter (S/m).

Data Types:double

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

Type of stub, specified as one of the following values:'NotaStub','Series','Shunt'.

Data Types:double

`Termination`—存根输电线路终止
`'NotApplicable'`(default) |`'Open'`|`'Short'`

存根输电线路终止, specified as one of the following values:'NotApplicable','Open','Short'.

Data Types:double

`Thickness`—Physical thickness of microstrip
`5.0e-6`(default) |scalar

Physical thickness of microstrip, specified as a scalar in meters.

Data Types:double

`Width`—Physical width of parallel-plate
`6.0e-4`(default) |scalar

Physical width of parallel-plate, specified as a scalar in meters.

Data Types:double

Object Functions

`analyze`	Analyze RFCKT object in frequency domain
`calculate`	Calculate specified parameters for rfckt objects or rfdata objects
`circle`	Draw circles on Smith Chart
`extract`	Extract specified network parameters from rfckt object or data object
`listformat`	List valid formats for specified circuit object parameter
`listparam`	List valid parameters for specified circuit object
`loglog`	Plot specified circuit object parameters using log-log scale
`plot`	Plot circuit object parameters on X-Y plane
`plotyy`	Plot parameters of RF circuit or RF data on X-Y plane with two Y-axes
`getop`	Display operating conditions
`polar`	Plot specified object parameters on polar coordinates
`semilogx`	Plot RF circuit object parameters using log scale forx-axis
`semilogy`	Plot RF circuit object parameters using log scale fory-axis
`smith`	Plot circuit object parameters on Smith chart
`write`	Write RF data from circuit or data object to file
`getz0`	Calculate characteristic impedance of RFCKT transmission line object
`read`	Read RF data from file to new or existing circuit or data object
`restore`	Restore data to original frequencies
`getop`	Display operating conditions
`groupdelay`	Group delay of S-parameter object or RF filter object orRF Toolboxcircuit object

Examples

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Microstrip Transmission Line

Open Live Script

Create a microstrip transmission line usingrfckt.microstrip.

tx1=rfckt.microstrip('Thickness',0.0075e-6)

tx1 = rfckt.microstrip with properties: Width: 6.0000e-04 Height: 6.3500e-04 Thickness: 7.5000e-09 EpsilonR: 9.8000 LossTangent: 0 SigmaCond: Inf LineLength: 0.0100 StubMode: 'NotAStub' Termination: 'NotApplicable' nPort: 2 AnalyzedResult: [] Name: 'Microstrip Transmission Line'

Algorithms

Theanalyzemethod treats the microstrip line as a 2-port linear network and models the line as a transmission line with optional stubs. Theanalyzemethod computes theAnalyzedResultproperty of the transmission line using the data stored in therfckt.microstripobject properties as follows:

If you model the transmission line as a stubless line, theanalyzemethod first calculates the ABCD-parameters at each frequency contained in the modeling frequencies vector. It then uses theabcd2sfunction to convert the ABCD-parameters to S-parameters.
Theanalyzemethod calculates the ABCD-parameters using the physical length of the transmission line,d, and the complex propagation constant,k, using the following equations:

$\begin{array}{l} A = \frac{e^{k d} + e^{- k d}}{2} \\ B = \frac{Z_{0} * (e^{k d} - e^{- k d})}{2} \\ C = \frac{e^{k d} - e^{- k d}}{2 * Z_{0}} \\ D = \frac{e^{k d} + e^{- k d}}{2} \end{array}$

Z₀andkare vectors whose elements correspond to the elements off, the vector of frequencies specified in theanalyzeinput argumentfreq. Both can be expressed in terms of the specified conductor strip width, substrate height, conductor strip thickness, relative permittivity constant, conductivity, and dielectric loss tangent of the microstrip line, as described in [1].
If you model the transmission line as a shunt or series stub, theanalyzemethod first calculates the ABCD-parameters at the specified frequencies. It then uses theabcd2sfunction to convert the ABCD-parameters to S-parameters.
When you set theStubModeproperty 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_inis 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 theStubModeproperty 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_inis 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] Gupta, K. C., R. Garg, I. Bahl, and P. Bhartia,Microstrip Lines and Slotlines, 2nd Edition, Artech House, Inc., Norwood, MA, 1996.

Version History

Introduced before R2006a

rfckt.microstrip

Description

Creation

Syntax

Description

Properties

AnalyzedResult—Computed S-parameters, noise figure, OIP3, and group delay valuesrfdata.dataobject

EpsilonR—Relative permittivity of dielectric9.8(default) |scalar

Height—Dielectric thickness or physical height of conductor6.35e-4(default) |scalar

LineLength—Physical length of transmission0.01(default) |scalar

LossTangent—Loss angle tangent of dielectric0(default) |scalar

Name—Object name'Microstrip Transmission Line'(default) |1-by-Ncharacter array|string scalar

nport—Number of ports2(default) |positive integer

SigmaCond—Conductor conductivityInf(default) |scalar

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

Termination—存根输电线路终止'NotApplicable'(default) |'Open'|'Short'

Thickness—Physical thickness of microstrip5.0e-6(default) |scalar

Width—Physical width of parallel-plate6.0e-4(default) |scalar

Object Functions

Examples

Microstrip Transmission Line

Algorithms

References

Version History

See Also

`AnalyzedResult`—Computed S-parameters, noise figure, OIP3, and group delay values
`rfdata.data`object

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

`Height`—Dielectric thickness or physical height of conductor
`6.35e-4`(default) |scalar

`LineLength`—Physical length of transmission
`0.01`(default) |scalar

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

`Name`—Object name
`'Microstrip Transmission Line'`(default) |`1-by-N`character array|string scalar

`nport`—Number of ports
`2`(default) |positive integer

`SigmaCond`—Conductor conductivity
`Inf`(default) |scalar

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

`Termination`—存根输电线路终止
`'NotApplicable'`(default) |`'Open'`|`'Short'`

`Thickness`—Physical thickness of microstrip
`5.0e-6`(default) |scalar

`Width`—Physical width of parallel-plate
`6.0e-4`(default) |scalar