txlineDelayLossy

Create delay lossy transmission line

Since R2021a

Description

Use the txlineDelayLossy object to create a delay lossy transmission line. You can also use the txlineDelayLossy object to model a delay lossy transmission line in an RF system using the rfbudget object or the RF Budget Analyzer app.

Creation

Syntax

dlytxline = txlineDelayLossy

dlytxline = txlineDelayLossy(Name,Value)

Description

dlytxline = txlineDelayLossy creates a default delay lossy transmission line object.

dlytxline = txlineDelayLossy(Name,Value) sets Properties of the delay lossy transmission line using one or more name-value arguments. For example, dlytxline = txlineDelayLossy('Z0',75) creates a delay lossy transmission line with an impedance of 75 ohms.

Properties

Name — Name of delay lossy transmission line

'DelayLossy' (default) | string scalar | character vector

Name of the delay lossy transmission line, specified as a string scalar or character vector.

Example: 'Name','DLbased'

Example: dlytxline.Name = 'DLbased'

Z0 — Characteristic impedance

50 (default) | positive scalar

Characteristic impedance of the delay lossy transmission line, specified as a positive scalar in ohms.

Example: 'Z0',75

Example: dlytxline.Z0 = 75

LineLength — Physical length of delay lossy transmission line

0.0100 (default) | positive scalar

Physical length of the delay lossy transmission line, specified as a positive scalar in meters.

Example: 'LineLength',0.0200

Example: dlytxline.LineLength = 0.0200

TimeDelay — Time delay in delay lossy transmission line

4.7e-9 (default) | positive scalar

Time delay in the delay lossy transmission line, specified as a positive scalar in seconds.

Example: 'TimeDelay',3.7e-9

Example: dlytxline.TimeDelay = 3.7e-9

Resistance — Resistance value per unit of length

0.3000 (default) | positive scalar

Resistance value per unit of length of the delay lossy transmission line, specified as a positive scalar in ohm/meter.

Example: 'Resistance',0.3400

Example: dlytxline.Resistance = 0.3400

NumPorts — Number of input and output ports

Read-only: 2 (default) | positive scalar

This property is read-only.

Number of input and output ports of the delay lossy transmission line, returned as positive scalar.

Terminals — Terminals of delay lossy transmission line

Read-only: {'p1+' p2+' 'p1-' 'p2-'} (default) | cell array

This property is read-only.

Terminals of the delay lossy transmission line, returned as a cell array.

Object Functions

sparameters	Calculate S-parameters for RF data, network, circuit, and matching network objects
groupdelay	Group delay of S-parameter object or RF filter object or RF Toolbox circuit object
noisefigure	Calculate noise figure of transmission lines, series RLC, and shunt RLC circuits

Examples

Calculate Noise Figure of Lossy Transmission Line

Design a coaxial cable of 0.5 meters in length as a lossy transmission line with the characteristic impedance of 48 ohms.

dlossy = txlineDelayLossy("Z0",48,"LineLength",500e-3);

Calculate the noise figure at 1 GHz.

nf = noisefigure(dlossy,1e9)

nf = 
0.0136

Algorithms

The delay lossy transmission line object calculates the S-parameters for the specified frequencies. This calculation is based on the delay line's line length, resistance, and time delay. The S-parameters are calculated using the equation given.

$$\begin{array}{l}{\text{S}}_{\text{11}}\text{ = 0}\\ {\text{S}}_{\text{12}}{\text{ = e}}^{-p}\\ {\text{S}}_{\text{21}}{\text{ = e}}^{-p}\\ {\text{S}}_{\text{22}}\text{ = 0}\end{array}$$

Here, $${\text{p = α}}_{\text{a}}\text{ + (i}\times \text{β)}$$. ɑa in p is the attenuation coefficient and β is the wave number.

The attenuation coefficient, ɑa, is related to the loss, ɑ, by

$${\text{α}}_{\text{a}}\text{ = }\frac{\text{(linelength }\times \text{ resistance)}}{\text{(2Z)}}$$

and the wave number β is related to the time delay, D, by

$$\text{β = 2 }\times \text{π }\times \text{ f }\times \text{ D}$$

where f is the frequency range specified in the S-parameters input argument.

Version History

Introduced in R2021a