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best antenna height

Discussion in 'CB Antennas' started by billsjca, Feb 14, 2011.

  1. billsjca

    billsjca
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    obvious that antenna height affects preformance and is critical, often heard one wave length is the best but also that 1.5 but less then 3 wave lengths is good.http://www.tennadyne.com/facts.htm any thoughts or experience. I'm running a sigma4 twenty feet up. and it works pretty good.having problems finding a push up mast longer then 20ft locally. any ideas?


     

  2. radiohobby

    radiohobby
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    For a dipole slightly below 1 wavelength gives the best radiation pattern. For other antennas I don't think the height really affects the radiation pattern since there are usually things attached to the antenna that controls the pattern instead of the earth.
     
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  3. wavrider

    wavrider
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    W9WDX Amateur Radio Club Member

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    Basic rule of height compared to take off angle or angle of radiation.

    Minimum of 1/2 wl in the air to get a decent angle of radiation for DX.

    Height is might on HF when dealing with line of sight
    (local rag chews) so the higher you can get your antenna the further you will be able to transmit and receive local comms.

    When I was just getting into the hobby over 30 years ago I asked one of my elmer's how high should I put my antenna up? He looked at me and laughed then said " To the moon".
     
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  4. W5LZ

    W5LZ
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    Crotchety Old Bastard

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    Antenna height is important, but I wouldn't call it critical by any means. YOUR antenna height is 'best' when it is as high as you can manage and still stay reasonable/practical. That height won't be the same for everyone! Of course, higher would probably be better, but then you have to stay at least 'close' to practical (that antenna will be the least of the cost, the 'other' stuff climbs in price along with the height).
    - 'Doc

    Quit somewhere around 1/10 of a mile...
     
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  5. Henry HPSD

    Henry HPSD
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    19DX348

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    Hi there,

    @Radiohobby:
    The rules for heigth above ground apply for all antennas so it will have influence on all not just a dipole.
    Though there is a significant difference between verticals and horizontal antennas.
    Your "just below 1wl" answer...That would give a take off angle of about 15 degrees for a horizontal dipool..(average ground conditiones) why would that be a indication as beeing the best?

    @Billysjca
    For local "line of sigth" talking ...the higher the futher your antenna can "see" and therefor you can talk "futher".

    For Dxing there is a big difference between a vertical and a horizontal antenna.

    For all antennas with similair polarisation heigth will have about the same influence.

    The rule waverider is refering too about a minimal half wave above ground,
    goes for horizontal antennas.

    A vertical antenna can be "sitting" on the ground to have a low angle. BUt that isnt the best for "local" work!

    There is no "optimum" heigth and neither will 3 wavelengths up in the air be "too high"
    Depending on what you are looking for there is a "optimum heigth".
    But for "real" DX one needs to lower that angle below the 10 degrees on 11 meter.

    Please read:
    http://www.dx-antennas.com/Height versus take off angle.htm
    (the part about the quad isnt accurate, but i didnt knew that when i wrote it about 8 years ago..ill update the page asap.).

    ALso in the vertical sections there are several TOA diagrams for different vertical antennas and at different heigths..though it is metric.

    When your in a "desert" enviroment ...verticals re terrible DX antennas.
    If you can place your 1/4 wave vertical antenna in the ocean...it will be quite difficult to beat!

    Hope it helped.

    Kind regards,

    Henry
     
  6. office888

    office888
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    Approximately 30-50 ft off the ground. Best compromise between price and performance.
     
  7. BOOTY MONSTER

    BOOTY MONSTER
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    like the Crotchety Old Bastard said , higher is better , but $$$ probably keeps %99 of folks from going as high as they would like to . folks on mobiles talk all over the place so getting a base antenna waaayyyy up there isn't necessary to have good results , but it will give better results . IMO the most important thing is to have the bottom of the antenna at least several feet above the peak of your house .
     
  8. TexasOutlaw

    TexasOutlaw
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    Im only about 30' to the base of my Antron. In the next week or so am going to build something to do away with the push up poje and go about 60' to the base of the antenna.:w00t:
     
  9. BOOTY MONSTER

    BOOTY MONSTER
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    be sure to write down the signal strengths of stations farther away from you that you talk to regularly so you can compare them after you raise the antenna higher so you can share the results wth us . ;)
     
  10. billsjca

    billsjca
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    Bid for san Jose wind storm blew thru last night and I dropped my mast so it is 10 ft off the ground . still made a contact 100+ miles away, to the sierra foot hills this morning. the station has an Imax 140 ft up a pine tree I normally hear him better but we could easily talk. low noise this morning the pre amp helped. he said I was a s3, he was in the noise but I could hear him guess the distance is 150 miles. a group of station aere in that area and I have made contact with about 5 of them. most are 2-3,00 ft on a mountain and have antennas up a tall tree.
     
  11. Charlie Brown

    Charlie Brown
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    certifiable

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    I have an IMAX at 50' at the base. I talked to a guy 150 miles away the other night. He also had an IMAX .. His antenna was at 103' he said.. HE ALSO had a set up moonraker 4 beams @ 60' He was putting 5 "S" units on me with the IMAX and 6 "s" units with the beams..! I was putting nothing on him but modulation when he was on the IMAX and 1 "s" unit on him when he switched to his beam.. Man that 40' makes a huge difference huh LOL...... Seriously I was not impressed by the beam antenna!!! I dont really like fiberglass antennas but man that imax was talkn with a 4 element quad!!:oops::oops:
     
  12. C2

    C2
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    It implies that he was running more power than you.

    Antenna gain (or loss) is reciprocal, so if his height made him get out more, it would help him receive more too.
     
  13. oldtoys1961

    oldtoys1961
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    C2 is right. He's just running more watts. Its nothing to see people running a thousand watts these days. I get bleed over from a local running 1200watts from channel 29 all the way down to channel 1. Man that piss's me off when that old bastard gets on there.
     

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