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I am looking for plans for a 20m Isotron antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KA7BSA, Mar 27, 2011.

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  1. KA7BSA

    KA7BSA Ham Member QRZ Page

    I am looking for plans for making a 20 meter Isotron antenna. I like to make one of these antennas, it looks interesting. Do you have or know where I can find plans.
  2. NA0AA

    NA0AA Ham Member QRZ Page

    Go to hardware store, buy a porcelain wall mount lamp socket and a 150 watt lamp. Feed with RG-58 and mount it up high. Cheaper and likely as effective.
  3. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    Everyone, so it seems, is trying to find the world's best antenna. The real truth is, it is fairly difficult to beat a plane old dipole. If you need a vertical (limited space?), look at a 6BTV. With adequate radials, it is as efficient as any, and better than most.
  4. NA0AA

    NA0AA Ham Member QRZ Page

    Yep, worlds best is a bit subjective innit?

    Another good wire antenna wold be a bisquare for 20.
  5. W5DXP

    W5DXP Ham Member QRZ Page

    A 20m hamstick dipole would perform better.
  6. K8JD

    K8JD Ham Member QRZ Page

    I had the world's best miniture antenna (my first antenna)...until I got a different one and now it's the words best (in my experience)
  7. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Ummm, let me get this right. You want us to help you get details of a patented antenna design, from an active manufacturer, so you can bootleg it???

    Sure. ;)

    How about buy one new and support the ham economy, or buy a used one in the swapmeet forum!!!
  8. KA7BSA

    KA7BSA Ham Member QRZ Page

    You can make anything you want for personal use, if you sell it is another matter. Thank you for your thought less comments.
  9. KA7BSA

    KA7BSA Ham Member QRZ Page

    I just like building antennas for the fun of it. I have found that a half square dipole works far better than a straight old dipole. I think that this Isotron antenna looks very interesting and I want to make one. Sure I could purchase one but, I want to learn how they work.
  10. W5DXP

    W5DXP Ham Member QRZ Page

    Mostly feedline radiation.
  11. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    Sure, you can build anything you like. I've thought of this myself. I already an Isotron 80m. So, get off your duff and do it!

    But it takes a lot of nerve to get on a national forum and ask other hams to help you undercut an honest long-standing ham vendor!
  12. KA7BSA

    KA7BSA Ham Member QRZ Page

    [FONT=&quot]You have your right to your opinion, that is what America is all about. I am not undercutting anybody with my question, first of all I am not planning on purchasing a commercial antenna when I can figure out how to make one. If, you do not want to help other Ham operators then I suggest you find another hobby. That is what the hobby is about helping others, and figuring out how to make things RIGHT? Great inventions start with someone else's ideas that are improved upon. [/FONT]
  13. W8NSI

    W8NSI Ham Member QRZ Page

    Plans for an isotron?

    As you have just experienced, you've been punked because no one really knows the answer to what you want, mainly because that particular design antenna is not efficient or popular. If it was such a great design people would be swapping their pictures of how they homebrewed one... for example: The hex beam (by Traffie Tech) is being made by hams and pictured in a Yahoo Hexbeam Group. Many are homebrewed, but other companies are making all the parts you need to build them better than the original Traffie design. But no one is making parts to build your own home rolled isotron. Hmmm must be a reason not involving lawsuits.

    Most people consider the isotron as an antenna of LAST resort or abject desperation. The suggestion about using a light bulb on the end of a piece of coax and elevating it up in the air would probably work as well. Actually you could feed that light bulb with coax or open wire feeder with about as good results. You could improve its efficiency by adding a couple wires attached to each side as a dipole.
  14. KB5HAB

    KB5HAB Ham Member QRZ Page

    Having owned one for 40m and 80m all I can say is they were both a coil of wire in between two aluminum plates. Look at the pictures on the website and break out the resonant frequency formulas... shouldn't be too hard to come up with a "workable" design. I'll not go into how good they do or do not work, only say that in the absense of available space they do work better than nothing and will get someone on the air. I only considered them for those 2 bands as I had enough roof space to put up a dipole for 14 through 30 mhz and dipoles do work well.
  15. W5DXP

    W5DXP Ham Member QRZ Page

    It is a low-Q resonant tank circuit connected to the end of a transmission line. The multi-turn coil is the inductor and the aluminum plates are the capacitor. It is a lot like a multi-turn loop antenna which is known to be notoriously inefficient.
  16. KA7BSA

    KA7BSA Ham Member QRZ Page

    Being a fairly new to the hobby this antenna looks interesting to me. I like to make things, being a machinist triggers my need to make and learn at the same time. I really want to thank you all for the suggestions and information. My plans are not to purchase any commercial antennas not because I am cheap, it's I want to understand how they work. I would love to make my own towers only if I had a shop big enough to do that.
  17. W1YW

    W1YW Subscriber QRZ Page

    I don't believe the patent is still active. Likely off-patent. Worth checking.

    The 20M isotron is not a poor performer. If you can get it up very high(say 60 feet or more) it will work well for DX. About the same size as a mag loop for example. A 20M dipole at that same height will work much better, by about 6-10 dB. If you can only raise a dipole to much less than 1/2 that height, and/or have covertness issues, the isotron is a fine antenna.

    Isotrons for 80M, or 160M, for example have very low radiation resistance and are not good performers, IMO.
    Chip W1YW
  18. W1YW

    W1YW Subscriber QRZ Page

    Actually the isotron sells pretty well. I used two, 30M and 20M, manyyears ago. The light bulb suggestion is a poor one and fraught with danger as a fire hazard.
  19. W1YW

    W1YW Subscriber QRZ Page

    Cecil:) ALL antennas are tank circuits. Slosh slosh:)

    Chip W1YW
  20. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Juergen DL7PE did a pretty good analysis of the Isotron design and includes some design formulas and stuff here:

    I think this was all published in Antennex years ago.
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