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Thread: Antenna matching network calculator?

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  1. #1
    Join Date
    Feb 2003
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    Default Antenna matching network calculator?

    I'm playing around in EZNEC with some antenna designs to put up for the summer in place of my former 160 meter inverted-L. To that end, I'm looking for a web site or free software to calculate the proper matching network design (T-network, L-network, simple series L or C) and also calculate the values for that design, to match 75 ohm coax to numbers like "Impedance = 140.4 + J 629.8 ohms". I know how to re-invent the wheel, but I don't want to. :-)

    I've searched, but came up with nothing.

    Any suggestions?
    73, Mike
    http://www.w0btu.com

  2. #2

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    Check out http://www.smeter.net/antennas/antennas.php. There is quite a bit there, with free design software.

  3. #3
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    Quote Originally Posted by WA7PRC View Post
    Check out http://www.smeter.net/antennas/antennas.php. There is quite a bit there, with free design software.
    Thanks, but every time I visit that site, it is unbelievably slow. Today is no exception, but at least it didn't time out continually.
    I did finally manage to fill out their contact form asking them about their speed problem.
    73, Mike
    http://www.w0btu.com

  4. #4

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    Mike,

    The "classic" way would be to use a Smith Chart. There are electronic versions around for free download which make the matching task trivial, eg:

    http://www.fritz.dellsperger.net/

    Here's a Smith Chart matching solution to your example, using a simple L network at a frequency of 1.9MHz:



    73,
    Steve G3TXQ

  5. #5
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    Quote Originally Posted by G3TXQ View Post
    The "classic" way would be to use a Smith Chart. There are electronic versions around for free download which make the matching task trivial, eg:http://www.fritz.dellsperger.net/
    Thanks! But I can't get the program to run, either under WINE or Windows XP running under VirtualBox. I'll try later on another PC running Windows 7.
    73, Mike
    http://www.w0btu.com

  6. #6

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    MMANA-GAL (Free antenna modeling software), has built-in calculator for LC match.

    Also, there's Java applet for T-Tuner calculations:

    http://dl2kq.de/mmana/4-10.htm

  7. #7

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    Quote Originally Posted by W0BTU View Post
    Thanks! But I can't get the program to run, either under WINE or Windows XP running under VirtualBox. I'll try later on another PC running Windows 7.
    Mike,

    Try the earlier version 2.03 - it runs fine under XP.

    I downloaded his latest version and found I needed to install Microsoft .NET Framework 3.5 to get it to run.

    73,
    Steve G3TXQ
    [COLOR=#808080][SIZE=1]"In physical science the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be." (Lord Kelvin 1824-1907)[/SIZE][/COLOR]

  8. #8

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    Quote Originally Posted by 4L4AGU View Post
    Also, there's Java applet for T-Tuner calculations:

    http://dl2kq.de/mmana/4-10.htm
    On that applet, how do you change the required matching impedance to 75 Ohms as the OP wanted?

    Steve G3TXQ

  9. #9

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    Only by re-compiling the source code, and changing z0x = 50.0; to 75.....

  10. #10

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    I still use an old DOS program called MicroSmith, v2.01, written by Wes Hayward, w7Zoi, that will do the job. It will run under XP. Back in the 1990's, it was available from the ARRL. I don't know about present availability.
    73, Cecil, www.w5dxp.com
    Can CO2 emissions save us from the coming ice age?

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