RFSim99 Download

RFSim99 is a freeware software that can help you in RF simulation, in your projects, especially if you are trying to design radio filters.

RFSim99 works with S-parameters. This means that not only will it simulate and analyse circuits built out of its internal library of components, but that it can accommodate any circuit block or stage for which these are known.

Installing RFSim99 on Windows 7 64-bit OS

You can download the archived software using the link below, unzip it and then it should work properly. Thanks to Flyb4ck!

Here is how to make RFSim99 work on Windows 7 64-bit OS. You must be running Windows 7 Professional OR Windows 7 Ultimate. Upgrade if you are running anything less. Next, download the Windows Virtual XP Mode for Windows 7 64-bit OS from Microsoft. This will allow you to run any XP program from Windows 7, 64-bit OS. It can be downloaded from Microsoft here: . Next, install RFSim99 under the Virtual XP Mode. It works great.
Best regards,
Chris Hudgins

RFSim99 software screenshot


Video presentation of the software

Please write your opinion and give us a feedback in the comments section about this great rf simulator tool. Did you encountered any problems with it?

The video below shows a Touchstone S-parameter s2p file that was generated on a homebrew N2PK VNA being simulated in RFSim 99. The s-parameter s2p file is for a ITT 10.7MHz roofing filter.


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  • sbrettsc

    I’m concerned of the accuracy of the physical inductor models. The physical model lets you set the SRF, Q, and Qf. And then gives you choices on how Q is extrapolated for other frequencies. I don’t think the extrapolation is being done in the way they say it is.

    I was wondering if anyone has the specific model equations that the simulator is using for they physical inductor model?

  • Frank

    I have been using this stuff along with my own software (PowerSmith) for a while. The conversion utility from WinBlows7 to run WinXP does not work always, every machine is different.
    However, the are minimum anomalies, such as:
    – The (-80dB) level window is OK on Win98, with XP and WinBlows7 it is partially covered.
    – Errors: In the GHz range, the Zs impedance model has up to 80% error. The Zp impedance is fine. Seems to be floating point problem, rounding, short mantissa.
    – The transmission line model had problems as grounded stub. can’t remember. The Series transmission line is OK.

    This software package is worth of recompiling and correcting the mistakes.

  • Eric


    Suggested solution works!
    I like the W7 look more than then the Windows classic so I will switch only when using RFSim99.
    I’ve tried to manage the settingsfile but that was without results.
    I still hope for a more definitive solution but can live with this one 🙂

    Thanks a lot for your help.

  • Flyb4ck

    I haven’t used the program recently but I remember that problem… and I found the solution only now!
    The incompatibility seems to be relate to the general theme of Windows 7. Try to go in the “Control Panel” -> “Personalization”, scroll down until you find “Windows classic”. When you select and apply it the graphics of the windows will change and they will appear like the old Windows 2000 🙂 Now you should be able to see the limits in the plots. Give it a try and tell me if it works!

  • Eric

    Hello all,

    I’m using this sofwtare under W7 professional 64 bits.
    No problems with running the software.
    But in the simulation screen I can hardly see the fileds used for the minimum trace limits.
    See axample of the left bottom of the screen.
    I’ve seen this in example viedeos as well?
    Was anyone able to solve this?

    Thanks in advance,

  • Flyb4ck

    I see people still commenting on this page so I’m assuming there is still interest in this software.
    I want to share my finding: the problem is that setup can’t run under the newest Windows OSs. So I installed using Windows XP and then moved every file on Windows 7. It seems to work good but I ask you if you can test it as well.
    You can find the software ready to be uncompressed here:

  • Tin Zaw Cho

    Does not work windws 7 Problem.

  • Justin

    I have 64bit Win7 Home Premium.

    I loaded the Virtual PC from

    The program still woudldn’t install, but thanks to the tips here, I loaded it onto an old 32 bit machine and just moved the files across.

    It’s now running fine on 64Bit Win7 Home Premium. There seems to be no need for win7 Professional or Ultimate.

  • André GRANGE

    Good software. It can be used under Linux and Wine.

  • JJJ

    Thanks a lot.

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