Matlab RFutilities
Written and tested on MATLAB Version 5
Hopefully all will be well on subsequent versions...
These Matlab mfiles were originally written to display measured
or calculated input impedances. The collection of routines
allows data to be plotted as Smith Chart, Admittance Chart,
Return Loss, VSWR and Mismatch Loss. Frequency markers can be
added to each of the plot types.
Over time the routines have been added to so that measured/calculated
impedance can be modified before display. A simple transmission line
model allows measured data to be deembedded (using a –ve length).
Matching can be achieved using lumped L,C,R elements or transmission lines.
There are CITI file loaders for the HP standard data format and a
time domain reflectometry function (actually chirpZ transform) to
display impedance as a function of distance.
The routines that deal with input impedance use the form Zin=A+jB Ohms,
rather than the reflection coefficient S11,S22 etc. This is simply because
I feel it is easier and more intuitive to work with input impedance in
this form.
An additional set of routines to display the transmission parameters :
Insertion Loss, Phase Delay and Group Delay use the usual Sparameter
form S21,S12 etc. Again because I feel it is easier to work with
transmission parameters in this form.
There are routines to convert between S11 and Zin there is a function
to convert standard Sparam to mixed mode Sparam, allowing differential
and common mode impedances to be displayed.
The latest addition to the routines allow the design and analysis of stepped
and tapered line impedance transformers. These include Chebyschev and Binomial
stepped transformers; Exponential , Triangular and Klopfenstein tapered line
transformers. There are also routines for realising the designs as Microstrip
layouts and exporting them from Matlab to AutoCad DXF format. Finally, there
is also a routine for designing broadband Wilkinson splitters.
All mfiles have helpcomments and there are numerous example scripts.
The files are split between 3 folders RFutils, RFutils_S and Rfutils_M.
Ideally these should be copied into the Matlab toolbox directory so the
search paths become : C:\Matlab\toolbox\RFutils, C:\Matlab\toolbox\RFutils_S
and C:\Matlab\toolbox\RFutils_M.
Once you have copied the files and added them to Matlab's search paths,
type :
help rfutils  lists all the functions in Rfutils and Rfutils_S
example1  run example1 etc...through to 11
help rfutils_m  lists all the functions and examples in Rfutils_M
Thankyou for taking the time to give these utilities a whirl, enjoy!
N. Tucker www.activefrance.com
