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S-Parameters Calculation - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


Quasar
Post subject: S-Parameters Calculation Posted: Sun Aug 13, 2006 3:51 pm

Captain

Joined: Fri Aug 11, 2006 6:07 am
Posts: 5
Is there a way to find the S-Parameters of a system without doing all the calculations to get them? Assume that I have a passive R network, is there a simulation program I can put this circuit into and have it calculate the S-Parameters for it?


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IR
Post subject: Posted: Tue Aug 15, 2006 5:59 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello,

Basically any known RF simulation program will be able to calculate the S-Paramaters of a passive R network (I assumre it is an attenuator). You can try: Microwave Office and Genesys for example.

_________________
Best regards,

- IR


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fred47
Post subject: RF SimulatorPosted: Tue Aug 15, 2006 11:28 am

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
Hi!

Just a note on simulators:

Virtually every SPICE-based simulator can be convinced to give you an impedance R+jX, which can relatively easily be converted to S11 and S12.
Free versions are readily available - for example, NGSpice.

Linear Technology provides a remarkably good version of SPICE for free download, called "SwitcherCAD" or "LTSpice". (Their angle: they provide models only for Linear Technology's products. I can't criticize them for that, because many device models are available online).

For small circuits, many providers will give you free "crippleware" - which is good enough for small circuits. (PSpice from Mentor Graphics/OrCad and TopSpice from Penzar Research, for example).

S12 and S21 can be gotten with not much more effort with the AC simulation facility in SPICE. If you've got a pocket calculator, you can get S parameters from Z or Magnitude/Angle.

A free/open source RF simulator is "qucs", available online from SourceForge. It's still relatively undeveloped, compared to Genesys or Microwave Office, but if you're not yet to the point where those programs pay for themselves, it's a way to get started.

Good Luck!
Fred


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kpainter
Post subject: Posted: Tue Aug 15, 2006 4:54 pm

Colonel


Joined: Wed Aug 20, 2003 11:47 am
Posts: 47
Location: Santa Barbara, CA
There is a free RF simulator called RFSim99 that is pretty nice that outputs S-Parameters directly. One link to get it is here:

http://www.101science.com/RFSim99.exe


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fred47
Post subject: SimulatorPosted: Tue Aug 15, 2006 8:39 pm

General


Joined: Wed Feb 22, 2006 3:51 pm
Posts: 104
KPainter -

RFSim99.exe - I forgot about that one! It has the advantage of being a Windows program, so easy to use and install. While it's not being updated anymore as far as I know, it's a good piece of work.

--Fred



Posted  11/12/2012
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