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Describe system in matlab in forms of S21

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neoflash

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In matlab, I have s-parameter files, how I descrite a system with its S21?

Normally, we describe system in forms of TF.

thanks
 

xxargs

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neoflash said:
In matlab, I have s-parameter files, how I descrite a system with its S21?

Normally, we describe system in forms of TF.

thanks


TF ??? (is more easy to written with full name, not shorten, for peoplea as me
to understud what you mean - i not familar of details in matlab for example)


S-parameter is normaly decribes

in polar form

___F___________S11__________S21___________S12___________S22____
frequency magnitude angle magnitud angle magnitude angle magnitude angle


70000000 -.0104 166.94 -73.576 64.595 -70.696 60.687 -.0328 167.12
70062500 -.0113 166.93 -72.333 59.873 -70.948 70.377 -.0203 167.17
70125000 -.0065 166.90 -70.322 68.316 -70.840 61.826 -.0271 167.15
70187500 -.0096 166.94 -72.801 61.135 -71.201 63.241 -.0289 167.12
...


or some cases in cartesian form simular

3.06686E-1,-2.30331E-1
2.86285E-1,-3.19656E-1
2.33062E-1,-4.09332E-1
1.45492E-1,-4.84909E-1
0.30853E-1,-5.31860E-1
...

Both case may find 'hint' on order, type of data and scale in begining of file like:

for polar:

! Frequency S11 S21 S12 S22
# HZ S DB R 50

or cartetisian (rectangular) note:

NAME DATA
VAR FREQ MAG 801
DATA S[1,1] RI
DATA S[2,1] RI
DATA S[1,2] RI
DATA S[2,2] RI
SEG_LIST_BEGIN
SEG 70000000 120000000 801
SEG_LIST_END

examples above taken from NVA hp8753


but different intrument manufacture and software can use different format and scale (db, SWR, rad, degree etc.) so read spec and textfile carefully and many programs import filter can read this hint and use data on right way in most cases.

---

remember - all vaue handle power flow in different way between S-port in normalized form, not voltage, not ampere, so you must know system impedances and scale factor etc. to recalculate to component value etc.


/xxargs
 

neoflash

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Thanks for the reply.

matlab will read in touchstone files to create rf object. however, how to create a system in matlab linked to this s-param object.
 

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