rfckt.txline class - Package: rfckt

General transmission line

Syntax

h = rfckt.txline h = rfckt.txline('Property1',value1,'Property2',value2,...)

Description

Use the txline class to represent transmission lines that are characterized by line loss, line length, stub type, and termination.

h = rfckt.txline returns a transmission line object whose properties are set to their default values.

h = rfckt.txline('Property1',value1,'Property2',value2,...) returns a transmission line object, h, with the specified properties. Properties that you do not specify retain their default values.

Properties

AnalyzedResult	Computed S-parameters, noise figure, OIP3, and group delay values
Freq	Frequency data
IntpType	Interpolation method
LineLength	Transmission line length
Loss	Transmission line loss
Name	Object name
nPort	Number of ports
PV	Phase velocity
StubMode	Type of stub
Termination	Stub transmission line termination
Z0	Characteristic impedance

Methods

analyze	Analyze circuit object in frequency domain
calculate	Calculate specified parameters for circuit object
circle	Draw circles on Smith chart
getz0	Characteristic impedance of transmission line object
listformat	List valid formats for specified circuit object parameter
listparam	List valid parameters for specified circuit object
loglog	Plot specified circuit object parameters using log-log scale
plot	Plot specified circuit object parameters on X-Y plane
plotyy	Plot specified object parameters with y-axes on both left and right sides
polar	Plot specified circuit object parameters on polar coordinates
semilogx	Plot specified circuit object parameters using log scale for x-axis
semilogy	Plot specified circuit object parameters using log scale for x-axis
smith	Plot specified circuit object parameters on Smith chart
write	Write RF data from circuit or data object to file

Examples

Construct a general transmission line, trl, with the default characteristic impedance of 50 ohms, phase velocity of 299792458 meters per second, and line length of 0.01 meters. Then perform frequency domain analysis from 1.0 GHz to 3.0 GHz. Plot the resulting S₂₁ network parameters, using the 'angle' format, on the X-Y plane.

trl = rfckt.txline('Z0',75)

trl =
 
             Name: 'Transmission Line'
             nPort: 2
             AnalyzedResult: []
             LineLength: 0.0100
             StubMode: 'NotAStub'
             Termination: 'NotApplicable'
             Freq: 1.0000e+009
             Z0: 75
             PV: 299792458
             Loss: 0
             IntpType: 'Linear'

f = [1e9:1.0e7:3e9];     % Simulation frequencies
analyze(trl,f);          % Do frequency domain analysis
figure
plot(trl,'s21','angle'); % Plot magnitude of S21

References

Ludwig, R. and P. Bretchko, RF Circuit Design: Theory and Applications, Prentice-Hall, 2000.

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