**Class: **rfckt.cpw**Package: **rfckt

Computed S-parameters, noise figure, OIP3, and group delay values

`rfdata.data`

object

Handle to an `rfdata.data`

object
that contains the S-parameters, noise figure, OIP3, and group delay
values computed over the specified frequency range using the `analyze`

method. This property is empty by
default.

The `analyze`

method treats
the transmission line as a 2-port linear network. It computes the `AnalyzedResult`

property of a stub or as
a stubless line using the data stored in the `rfckt.cpw`

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:$$\begin{array}{l}A=\frac{{e}^{kd}+{e}^{-kd}}{2}\\ B=\frac{{Z}_{0}*\left({e}^{kd}-{e}^{-kd}\right)}{2}\\ C=\frac{{e}^{kd}-{e}^{-kd}}{2*{Z}_{0}}\\ D=\frac{{e}^{kd}+{e}^{-kd}}{2}\end{array}$$

*Z*_{0}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, slot width, substrate height, conductor strip thickness, relative permittivity constant, conductivity and dielectric loss tangent of the transmission 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 as shown in the following figure.*Z*is the input impedance of the shunt circuit. The ABCD-parameters for the shunt stub are calculated as:_{in}$$\begin{array}{c}A=1\\ B=0\\ C=1/{Z}_{in}\\ D=1\end{array}$$

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 as shown in the following figure.*Z*is the input impedance of the series circuit. The ABCD-parameters for the series stub are calculated as:_{in}$$\begin{array}{c}A=1\\ B={Z}_{in}\\ C=0\\ D=1\end{array}$$

The `analyze`

method
uses the S-parameters to calculate the group delay values at the frequencies
specified in the `analyze`

input
argument `freq`

, as described in
the `analyze`

reference
page.

tx1 = rfckt.cpw; analyze(tx1,[1e9,2e9,3e9]); tx1.AnalyzedResult ans = Name: 'Data object' Freq: [3x1 double] S_Parameters: [2x2x3 double] NF: [3x1 double] GroupDelay: [3x1 double] OIP3: [3x1 double] Z0: 50 ZS: 50 ZL: 50 IntpType: 'Linear'

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