nport

Create linear n-port circuit element

Description

The nport class creates an n-port object that can be added into an RF Toolbox™ circuit. The n-port S-parameters define the n-port object.

Creation

Syntax

nport_obj = nport(filename)

nport_obj = nport(netparamobj)

nport_obj = nport(___,name)

nport_obj = nport(Name=Value)

Description

nport_obj = nport(filename) creates an n-port object and sets the FileName property.

nport_obj = nport(netparamobj) creates an n-port object and sets the NetworkData.

nport_obj = nport(___,name) creates an n-port object and sets the Name property. Specify the name-value argument after any of the input argument combinations in the previous syntaxes.

nport_obj = nport(Name=Value) sets the Properties of an nport object using one or more name-value arguments. For example, nport_obj = nport(FileName='passive.s2p') creates an nport object from passive.s2p. Properties you do not specify retain their default values.

Properties

FileName — Touchstone file

string scalar | character vector

Touchstone file, specified as a string scalar or character vector.

Note

The Touchstone file must be passive at all specified frequencies. To make n-port S-parameters passive, use the makepassive function.

Data Types: char | string

Input — Input port number

[] (default) | scalar

Since R2023b

Input port number, specified as a scalar. Use this property to designate a port in a multiport (n-port) element as the input port.

The Input, Output, and Termination properties enable you to treat a multiport (n-port) element as a two-port element. You can use this two-port element in an rfbudget object to calculate the RF budget results for a chain of two-port elements.

Example: 1

NumPorts — Number of ports

scalar

Number of ports, specified as a scalar.

Example: 2

Output — Output port number

[] (default) | scalar

Since R2023b

Output port number, specified as a scalar. Use this property to designate a port in a multiport (n-port) element as the output port.

The Input, Output, and Termination properties enable you to treat a multiport (n-port) element as a two-port element. You can use this two-port element in an rfbudget object to calculate the RF budget results for a chain of two-port elements.

Example: 2

NetworkData — Network data

scalar

Network data, specified as a scalar. Network data can be of S, Z, Y, ABCD, h, or g-parameters.

NoiseData — Noise Data

noiseParameter object

Noise data of the n-port element, specified as a noiseParameters object. The noiseParameter object contains a frequency-dependent noise figure loaded from a two-port Touchstone file or built at the MATLAB® command line. To reset the n-port element to noiseless, set the NoiseData to [].

Specify the NoiseData property with the NetworkData property.

Example: NoiseData=np

Termination — Impedance to terminate unused ports

NetworkData.Impedance (default) | real scalar | real vector

Since R2023b

Impedance to terminate unused ports, specified as a real scalar or real vector of length NumPorts in ohms. When you do not specify an impedance, the object terminates the unused ports by assigning them to NetworkData.Impedance. To create a:

• Short-circuit termination — Set Termination to 0

• Open-circuit termination — Set Termination to Inf

The Input, Output, and Termination properties enable you to treat a multiport (n-port) element as a two-port element. You can use this two-port element in an rfbudget object to calculate the RF budget results for a chain of two-port elements.

Example: 75

Name — Name of n-port object

scalar

Name of n-port object, specified as a scalar.

Example: obj

Ports — Port names

cell vector

Port names, stored as a cell vector. This property is a read only.

Example: {’p1’ ‘p2’}

Terminals — Terminal names

cell vector

Terminal names, stored as a cell vector. There are two terminals per port. The positive terminal names are listed first ('p1+', 'p2+'...) followed by the negative terminal ('p1–', 'p2–'...). This property is read only.

ParentNodes — Parent circuit nodes connected to n-port object terminals

vector of integers.

Parent circuit nodes connected to n-port object terminals, stored as a vector of integers. ParentNodes is same length as Terminals. This property is read only and appears only after you add the n-port data.

ParentPath — Full path of circuit to which n-port object belongs

character vector

Full path of the circuit to which the n-port object belongs, stored as character vector. This property is read only and appear only after you add the n-port object is added to the circuit.

Object Functions

smithplot	Plot impedance transformation for selected matching network on smith chart
clone	Create copy of existing circuit element or circuit object

Examples

Create N-port Object

Create and display N-port data object.

npass = nport('passive.s2p')

npass = 
  nport: N-port element

       FileName: 'passive.s2p'
    NetworkData: [1x1 sparameters]
           Name: 'Sparams'
       NumPorts: 2
      Terminals: {'p1+'  'p2+'  'p1-'  'p2-'}

Add N-Port Object to Circuit

Add a N-port object to a circuit. Display the object.

nobj = nport('passive.s2p');
ckt = circuit('example');
add(ckt,[1 2],nobj)
disp(nobj)

  nport: N-port element

       FileName: 'passive.s2p'
    NetworkData: [1x1 sparameters]
           Name: 'Sparams'
       NumPorts: 2
      Terminals: {'p1+'  'p2+'  'p1-'  'p2-'}
    ParentNodes: [1 2 0 0]
     ParentPath: 'example'

Treat Three-Port Element As Two-Port Element

Since R2023b

Input a three-port Touchstone file to the nport object. To treat a three-port element as a two-port element, specify the input and output ports. This example assigns the port 1 as the input port and the port 3 as the output port. The object terminates port 2 with NetworkData.Impedance.

nport_obj = nport('default.s3p',Input=1,Output=3);

Create two-port elements to add them to the RF budget chain.

a = amplifier(Gain=4);
m = modulator(OIP3=13);
r = rfelement(Gain=10);

Add the n-port element and other two-elements to an RF budget chain and compute the budget results for the chain of two-port elements.

b = rfbudget([a m r nport_obj],2e9,-30,1e3)

b = 
  rfbudget with properties:

               Elements: [1x4 rf.internal.rfbudget.Element]
         InputFrequency:   2 GHz
    AvailableInputPower: -30 dBm
        SignalBandwidth:   1 kHz
                 Solver: Friis      
             AutoUpdate: true

   Analysis Results
        OutputFrequency: (GHz) [  2    3    3       3]
            OutputPower: (dBm) [-26  -26  -16  -16.32]
         TransducerGain: (dB)  [  4    4   14   13.68]
                     NF: (dB)  [  0    0    0       0]
                   IIP2: (dBm) []                     
                   OIP2: (dBm) []                     
                   IIP3: (dBm) [Inf    9    9       9]
                   OIP3: (dBm) [Inf   13   23   22.68]
                    SNR: (dB)  [114  114  114     114]

Version History

Introduced in R2013b

R2023b: Treat multiport n-port element as two-port element

Use the Input, Output, and Termination properties of the nport object to treat a multiport n-port element as two-port element. You can use this two-port element in an rfbudget object to calculate the RF budget results for a chain of two-port elements.

R2023b: Recommended over rfckt.passive and rfdata.noise

nport is recommend over rfckt.passive and rfdata.noise because it enables you to:

• Create passive RF S-parameter components and networks that are characterized by passive network parameter data.

• Model a passive RF S-parameter components in an RF chain created using an rfbudget object or the RF Budget Analyzer app.

• Export the passive RF S-parameter components to RF Blockset™ or to rfsystem System object™ for circuit envelope or idealized baseband analysis.

• Build a n-port element with the noise data, specified as a noiseParameters object. The noiseParameter object contains a frequency-dependent noise figure loaded from a two-port Touchstone file or built at the MATLAB® command line.