Store output power and phase information for amplifiers or mixers

Use the `rational`

class to represent RF components using a
rational function object of the form:

$$F(s)=\left({\displaystyle \sum _{k=1}^{n}\frac{{C}_{k}}{s-{A}_{k}}+D}\right){e}^{-s\tau}\begin{array}{cc},& s=j2\pi f\end{array}$$

There are two ways to construct an rational function object:

You can fit a rational function object to the component data using the

`rationalfit`

function.You can use the

`rfmodel.rational`

constructor to specify the pole-residue representation of the component directly.

`h = rfmodel.rational`

returns a rational function
object whose properties are set to their default values.

```
h
= rfmodel.rational('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

`freqresp` | Frequency response of a rational function and rationalfit function object |

`stepresp` | Step-signal response of rational function object |

`rationalfit` | Approximate data using stable rational function object |

`ispassive` | Return true if rationalfit output is passive at all frequencies |

`makepassive` | Enforce passivity of a rationalfit output |

`passivity` | Plot passivity of N-by-N rationalfit function output |

`timeresp` | Time response for rational function object |

`writeva` | Write Verilog-A description of rational function object |

`generateSPICE` | Generate SPICE file from rationalfit of S-parameters |