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# makepassive

Enforce passivity of S-parameters

## Syntax

sparams_passive = makepassive(sparams)
hsp = makepassive(hs)

## Description

sparams_passive = makepassive(sparams) makes an array of S-parameters passive. Both sparams and sparams_passive are N-by-N-by-M arrays representing M N-port S-parameters.

The makepassive function enforces the following conditions on sparams:

$\begin{array}{c}S\left(-j\omega \right)={S}^{*}\left(j\omega \right)\\ {‖S\left(j\omega \right)‖}_{2}\le 1\end{array}$

The notation ${‖S‖}_{2}$ represents the 2-norm, or singular-value decomposition, of S.

hsp = makepassive(hs) creates a passive S-parameter object from the S-parameter object hs.

## Input Arguments

 hs N-port S-parameters, specified as an RF Toolbox™ S-parameter object. sparams sparams can represent either an active network or a passive network. To check if sparams is passive, use the ispassive function.

## Output Arguments

 sparams_passive The makepassive function uses a purely mathematical method to calculate sparams_passive. As a result, the array sparams_passive does not represent the same network as sparams. sparams and sparams_passive do not represent the same network unless sparams and sparams_passive are equal. The more closely sparams represents a passive network, the better the approximation sparams_passive is to that network. Therefore, makepassive generates the most realistic results when sparams is active only due to small numerical errors.

## Examples

Enforce passivity of the S-parameters that represent a passive network:

```ckt = read(rfckt.passive,'passive.s2p');
sparams = ckt.NetworkData.Data;
Is_Passive = ispassive(sparams)
sparams_new = makepassive(sparams);
Is_Passive = ispassive(sparams_new)
ckt.NetworkData.Data = sparams_new;
```