rfckt.microstrip

Microstrip transmission line

Description

Use the microstrip class 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).

Creation

Syntax

h = rfckt.microstrip

h = rfckt.microstrip('Property1',value1,'Property2',value2,...)

Description

example

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

h = rfckt.microstrip('Property1',value1,'Property2',value2,...) sets properties using one or more name-value pairs. You can specify multiple name-value pairs. Enclose each property name in a quote

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 as rfdata.data object. Analyzed Result is a read-only property. For more information refer, Algorithms.

Data Types: function_handle

`EpsilonR` — Relative permittivity of dielectric
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, $ε_{0}$ . The default value is 9.8.

Data Types: double

`Height` — Dielectric thickness or physical height of conductor
scalar

Dielectric thickness or physical height of the conductor, specified as a scalar in meters. The default value is 6.35e-4.

Data Types: double

`LineLength` — Physical length of transmission
scalar

Physical length of transmission, specified as a scalar in meters. The default value is 0.01.

Data Types: double

`LossTangent` — Loss angle tangent of dielectric
scalar

Loss angle tangent of dielectric, specified as a scalar. The default value is 0.

Data Types: double

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

Object name, specified as an 1-by-N character array. Name is a read-only property.

Data Types: char

`nport` — Number of ports
positive integer

Number of ports, specified as a positive integer. nportt is a read-only property. The default value is 2.

Data Types: double

`SigmaCond` — Conductor conductivity
scalar

Conductor conductivity, specified as a scalar in Siemens per meter (S/m). The default value is Inf.

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

Stub transmission line termination, specified as one of the following values: 'NotApplicable', 'Open', 'Short'.

Data Types: double

`Thickness` — Physical thickness of microstrip
scalar

Physical thickness of microstrip, specified as a scalar in meters. The default value is 5.0e-6.

Data Types: double

`Width` — Physical width of parallel-plate
scalar

Physical width of parallel-plate, specified as a scalar in meters. The default value is 6.0e-4.

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 specified circuit object parameters on X-Y plane
`plotyy`	Plot specified parameters on X-Y plane with Y-axes on both left and right sides
`getop`	Display operating conditions
`polar`	Plot specified object parameters on polar coordinates
`semilogx`	Plot specified circuit object parameters using log scale for x-axis
`semilogy`	Plot specified circuit object parameters using log scale for y-axis
`smith`	Plot specified circuit object parameters on Smith chart
`write`	Write RF data from circuit or data object to file
`getz0`	Get characteristic impedance of 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 or RF Toolbox circuit object

Examples

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Microstrip Transmission Line

Open Live Script

Create a microstrip transmission line using rfckt.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

The analyze method treats the microstrip line as a 2-port linear network and models the line as a transmission line with optional stubs. The analyze method computes the AnalyzedResult property of the transmission line using the data stored in the rfckt.microstrip object properties as follows:

If you model the transmission line as a stubless line, the analyze method first calculates the ABCD-parameters at each frequency contained in the modeling frequencies vector. It then uses the abcd2s function to convert the ABCD-parameters to S-parameters.
The analyze method calculates the ABCD-parameters using the physical length of the transmission line, d, and the complex propagation constant, k, using the following equations:

$\begin{array}{l} A = \frac{e^{k d} + e^{- k d}}{2} \\ B = \frac{Z_{0} * (e^{k d} - e^{- k d})}{2} \\ C = \frac{e^{k d} - e^{- k d}}{2 * Z_{0}} \\ D = \frac{e^{k d} + e^{- k d}}{2} \end{array}$
Z₀ and k are vectors whose elements correspond to the elements of f, the vector of frequencies specified in the analyze input argument freq. 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, the analyze method first calculates the ABCD-parameters at the specified frequencies. It then uses the abcd2s function to convert the ABCD-parameters to S-parameters.
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] Gupta, K. C., R. Garg, I. Bahl, and P. Bhartia, Microstrip Lines and Slotlines, 2nd Edition, Artech House, Inc., Norwood, MA, 1996.

Documentation

rfckt.microstrip

Description

Creation

Syntax

Description

Properties

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

`EpsilonR` — Relative permittivity of dielectric
scalar

`Height` — Dielectric thickness or physical height of conductor
scalar

`LineLength` — Physical length of transmission
scalar

`LossTangent` — Loss angle tangent of dielectric
scalar

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

`nport` — Number of ports
positive integer

`SigmaCond` — Conductor conductivity
scalar

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

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

`Thickness` — Physical thickness of microstrip
scalar

`Width` — Physical width of parallel-plate
scalar

Object Functions

Examples

Microstrip Transmission Line

Algorithms

References

See Also

RF Toolbox Documentation

Support

Documentation

rfckt.microstrip

Description

Creation

Syntax

Description

Properties

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

EpsilonR — Relative permittivity of dielectric scalar

Height — Dielectric thickness or physical height of conductor scalar

LineLength — Physical length of transmission scalar

LossTangent — Loss angle tangent of dielectric scalar

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

nport — Number of ports positive integer

SigmaCond — Conductor conductivity scalar

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

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

Thickness — Physical thickness of microstrip scalar

Width — Physical width of parallel-plate scalar

Object Functions

Examples

Microstrip Transmission Line

Algorithms

References

See Also

RF Toolbox Documentation

Support

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

`EpsilonR` — Relative permittivity of dielectric
scalar

`Height` — Dielectric thickness or physical height of conductor
scalar

`LineLength` — Physical length of transmission
scalar

`LossTangent` — Loss angle tangent of dielectric
scalar

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

`nport` — Number of ports
positive integer

`SigmaCond` — Conductor conductivity
scalar

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

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

`Thickness` — Physical thickness of microstrip
scalar

`Width` — Physical width of parallel-plate
scalar