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Model passive network using Z-parameters

Black Box Elements sublibrary of the Physical library

The Z-Parameters Passive Network block models the two-port passive network described in the block dialog box, in terms of its Z-parameters and their associated frequencies.

In the **Z-Parameters** field of the block
dialog box, provide the Z-parameters for each of M frequencies as
a 2-by-2-by-M array. In the **Frequency** field,
specify the frequencies for the Z-parameters as an M-element vector.
The elements of the vector must be in the same order as the Z-parameters.
All frequencies must be positive. For example, the following figure
shows the correspondence between the Z-parameters array and the vector
of frequencies.

The Z-Parameters Passive Network block uses the RF Toolbox™
`z2s`

function to convert the
Z-parameters to S-parameters, and then interpolates the resulting S-parameters to
determine their values at the modeling frequencies. The modeling frequencies are
determined by the Output Port block. See Map Network Parameters to Modeling Frequencies for more details.

**Z-Parameters**Z-parameters for a two-port passive network in a 2-by-2-by-M array. M is the number of Z-parameters.

**Frequency (Hz)**Frequencies of the Z-parameters as an M-element vector. The order of the frequencies must correspond to the order of the Z-parameters in

**Z-Parameters**. All frequencies must be positive.**Interpolation method**The method used to interpolate the network parameters. The following table lists the available methods describes each one.

Method Description `Linear`

(default)Linear interpolation `Spline`

Cubic spline interpolation `Cubic`

Piecewise cubic Hermite interpolation

For information about plotting, see Create Plots.

The following example specifies Z-parameters [0.13 - 5.93i,
.03-3.16i; 0.03-3.16i, .13-5.93i] and [0.27-2.86i, -.09-5.41i; -.09-5.41i,
.27-2.86i] at frequencies 2.0 GHz and 2.1 GHz respectively. It uses
the MATLAB^{®} `cat`

function
to create the 2-by-2-by-2 Z-parameters array.

cat(3,[0.13-5.93i, .03-3.16i; 0.03-3.16i, .13-5.93i],... [0.27-2.86i,-.09-5.41i; -.09-5.41i, .27-2.86i])

Type the following command at the MATLAB prompt to create a variable called

`zparams`

that stores the values of the Z-parameters.zparams = cat(3,... [0.13-5.93i,.03-3.16i; 0.03-3.16i,.13-5.93i],... [0.27-2.86i,-.09-5.41i; -.09-5.41i,.27-2.86i])

Set the Z-Parameters Passive Network block parameters on the

**Main**tab as follows:Set the

**Z-Parameters**parameter to`zparams`

.Set the

**Frequency (Hz)**parameter to`[2.0e9,2.1e9]`

.

Click

**Apply**. This action applies the specified settings.Set the Z-Parameters Passive Network block parameters on the

**Visualization**tab as follows:In the

**Source of frequency data**list, select`User-specified`

.Set the

**Frequency data (Hz)**parameter to`[1.9e9:1.0e8:2.2e9]`

.In the

**Y parameter1**list, select`S12`

.

Click

**Plot**. This action creates an X-Y plane plot of the S_{12}parameters in the frequency range 1.9 to 2.2 GHz.

General Circuit Element, General Passive Network, Output Port, S-Parameters Passive Network, Y-Parameters Passive Network

`z2s`

(RF Toolbox)

`interp1`

( MATLAB)