ad: Schulman-1

HF End-Fed Multiband that works well

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by KK4NSF, Aug 12, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: L-MFJ
ad: MessiPaoloni-1
ad: Subscribe
ad: K5AB-Elect-1
ad: Left-2
  1. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    I used to care about single wire antenna debates, until I started building wire yagis.

    Now I just SMH.
     
    W1VT and NH7RO like this.
  2. AF7TS

    AF7TS Ham Member QRZ Page

    And with this point I agree. The closer you can get to symmetry, the less you will need to compromise other aspects of your antenna system.

    I guess my big _semantic_ argument is that when you say that all antennas have two halves and are center fed, you imply that in an asymmetric situation the physics will somehow 'grab' metal elsewhere to create a symmetric situation. When what I am trying to say is that any material coupled to the antenna near field will be part of the antenna system, symmetric or not.

    73
    Jon
    AF7TS
     
    K7TRF likes this.
  3. AI3V

    AI3V Ham Member QRZ Page

    I see your point. And I agree with you.

    I also think that the farther away you get from a (and I'm having a tought time picking a single word :)) "classic" or "fundimental" or "basic" antenna, the harder it is to describe whats going on.

    Consider a "perfect" half wavelength, center fed, symmetrical dipole. (Hertz) let's assume a perfect balun at the feedpoint so we are using coax.

    Or a quarter wavelength Marconi, with a "perfect" ground plane, and the coax under the ground plane.

    Either is "easy" to explain.

    Now start changing things,

    Run the coax parallel to one of the dipole legs, or above the Marconi's ground plane, and "common mode" rears its ugly head.

    But things get more and more "fuzzy" with say, a 5/8th's wave vertical well above "ground", with 3, 1/4 wavelength "radials"- nothing symmetrical about this, yet run the coax below the radials and again -no common mode. But how to explain impedance of both halves, when if you add more radials the vswr will not change much, if at all! And what about that "common mode?!"

    Now add anecdotal evidence for the many, many "random wire" setups folks use, one guy throws a wire up in a tree and works the world, and the next guy has a "hot mic" and a computer that "locks up", and a irate neighbor pounding on her door...
    I'm rambling, but I really just want everyone to have a loud signal so I can talk to them :) and the most reliable way I know is to advise them to stick with simple, foolproof antennas.

    Rege
     
    K7TRF likes this.

Share This Page