Most Efficient Antenna for QRP

Discussion in 'QRP Corner' started by W7CJD, Dec 15, 2015.

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  1. W4SEX

    W4SEX Ham Member QRZ Page

    Great topic Connie, sounds like no straightforward answers on here either.:(

    I too was hoping to find someone who would reference efficiency when I started my SOTA antenna thread. I keep hearing as well, "anytime you use a tuner, you're wasting power, creating heat, and reducing antenna efficiency"
  2. WJ4U

    WJ4U Ham Member QRZ Page

    Radio Arcala had a good one. But, like the operators, it's Finnish.
  3. KC8VWM

    KC8VWM Ham Member QRZ Page

    I'm not really sure I really understand the question and that's why I haven't answered before.

    If the question is....-

    "Is 300 ohm feedline better to use than 50 ohm coax to feed a doublet as far as antenna system efficiency is concerned"

    Then I would conclude the answer is yes, it is.

    Why? How?

    Well for starters before we can answer that,

    #1 Is this a mono band or a multiband antenna we are talking about?

    #2 You made a reference to using it with coax. Does this mean it will no longer be a doublet, but it will function as a dipole instead? What are the "doublet" dimensions?

    #3 Confused... reference about using a balun or a 1:1 balun. A 1:1 balun is a common mode "choke" and not an impedance transformer right? Assumes the antenna in question is already 50 ohms?

    Not enough data to compute... :)
  4. W7CJD

    W7CJD Ham Member QRZ Page

    I just wanted to get the topic started.

    I wasn't asking you to critique an antenna for me.

    Begin anywhere you like..
  5. KC8VWM

    KC8VWM Ham Member QRZ Page

    I was attempting to answer, but apparently she just wanted to get the topic started?
  6. W7CJD

    W7CJD Ham Member QRZ Page

    I am asking give an example, you like.

    I ask, please provide the why and how.
  7. W8ZNX

    W8ZNX Ham Member QRZ Page

    answer to your question
    there is no answer
    there are too many variable conditions

    on a test range or in the lab
    there would be a most efficient

    but in real life there are too many variables
    as stated before a great antenna for 10 meters
    is not practical for 40
    do you want to rag chew with station
    200 miles away or work DX
    what kind of ground
    10 ft from the ocean or on a rocky hill side

    you are kinda asking

    "how many angels can dance on the head of a pin"

    you can do what most of us old time came up from Novice OPs did

    read the books
    read the books

    learned how to build wire antennas from George Grammar W1DF
    articles in QST and the League Handbook
    learned how to build a antenna tuner from Doug DeMaw W1FB
    also ARRL books and QST
    learned how to build Yagi and Quad antennas from books and
    magazine articles by Bill Orr W6SAI

    read the books
    look up old QST, 73 and CQ articles
    get some wire start building antennas

    this fall have been working on a inverted L for 160 and 80
    over the last two months have put it up taken it down changed things
    put it back up
    now gets out like gang busters

    dit dit
    Last edited: Dec 16, 2015
    KC8VWM likes this.
  8. AI6KX

    AI6KX Ham Member QRZ Page

    There is nothing more satisfying to a curious do-it-yourselfer than messing with wire antennas. The cost is negligible and the learning is enormous. Since the antenna bug bit me 11 months ago I have built and hung 12 antennas and took 9 of them down. The ones left standing are fantastic performers, on 40, 20, 17, 15 and 10. I hope to get 80 sorted out soon.

    Actually if I had a source of aluminum tubing I'd be messing with that too, but bamboo and thick anodized aluminum wire are much cheaper.


    Steve JS6TMW
    KU4X likes this.
  9. W7CJD

    W7CJD Ham Member QRZ Page

    Okay, your answer is read books and trial-and-error.

    Been there, done that.

    More recently than DeMaw and Orr, however, we have answers.

    I'll check out W1DF.

    I am looking for the "How" and "Why" from using an antenna analyzer, for example, and recent antenna modelling, where Eznec had started and more recent antenna modelling software is showing us.

    ..any one efficient antenna, how and why, is a start.

    QRP level output makes it all more imperative, while, in fact, running more power allows just getting by.
    Last edited: Dec 16, 2015
  10. W7CJD

    W7CJD Ham Member QRZ Page

    I have had the antenna bug many years, and read books and articles and online and made wire antennas.

    Are you running QRP?

    Will you describe the Why and How the antennas you have found work well for you, at least?

    You trimmed? You adjusted the height of the ends? You adjusted the height of the feedpoint? You adjusted the length of the feedline? You used an existing balun design or not? You made a balun? You used a common mode balun or choke, by any name seen in use? You decided a balanced feedline vs coax feedline? What?

    Would you share your decisions?
    Last edited: Dec 16, 2015

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