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Antenna stacking

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by LA1ZN, Jan 14, 2019.

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  1. LA1ZN

    LA1ZN Premium Subscriber QRZ Page

    Attached are two pictures of my antenna's,
    The lower one are A-3S Cushcraft and the one on top are unknown--- (got that used when I bought the used Tower ) ---- The top one is working very well on 40 m,but the A-3S is not doing too much ----I had the 40 m add in on that antenna, but doesn't do too much.?
    The spacing between them are approx. 3'------and Tower is on this picture approx. 40 ' up.
    Have a feeling that these two Antennas are interfering with each other ?
    Maybe just use one of them ?

    Any suggestions are welcome.
    73 JAN -- W2JAN --- LA1ZN
     

    Attached Files:

  2. W1VT

    W1VT Ham Member QRZ Page

  3. LA1ZN

    LA1ZN Premium Subscriber QRZ Page

    Thanks for feed back -------Can I put these 2 antennas in paralell , maybe ?
     
  4. W1VT

    W1VT Ham Member QRZ Page

    Antenna modeling is one way of handling very close spacing, but it may not be practical with an unknown antenna on top of a tower that works well.
     
  5. KM3F

    KM3F Ham Member QRZ Page

    Doing traditional combining, you can't get them far enough apart on 40m on the same tower to make a worthwhile difference and have to uses Q sections to get them to 50 ohms.
    Can't just Tee two antennas together. 50 to 50 = 25 ohms an SWR of 2 to 1.
    The Q sections are needed to get back to 50 ohms at the Tee point.
    Normally two identical antennas offer a gain of just under 3 db.
    These two, being quite different and close spaced isn't worth the effort and destroys any pattern one beam normally would have..
    3 db is normally given as 1 S units and you can't get them far enough apart for stacking.
    With what you have in the air now, I would consider single mono band 4 element and get a performance result far greater than what you now have and no stacking issue.
    Ever hear the Italian station that comes in at 10 and 20 over 9 on 40m? He uses a 4E mono plus power.
    Good luck.
     
    Last edited: Jan 15, 2019
    LA1ZN and NH7RO like this.
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I don't know what the upper beam is, either, but that's a very light-duty tower for two HF beams!

    Hope you leave it "cranked down" in the wind.:)
     
  7. LA1ZN

    LA1ZN Premium Subscriber QRZ Page

    Thank you for feedback -----
    I have heavy duty guy wires on the Tower , since this picture was taken ----and so far no issue with the wind-----, but I normally take it down if it will be heavy wind for a longer time.

    I will look into a 40 meter monoband ..or a dual band for 20 and 40 -- will research

    Also I will remove the upper ant. and see how it will work with only the A3s


    JAN
     
  8. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    I've installed a lot of towers like that; be careful guying them, as too much guy tension can buckle the upper section which cannot withstand much guying force.

    Those were mostly "TV antenna" towers intended for use without guying, but very small antennas with small wind loads.

    The "amateur radio antenna" towers all had upper sections large enough to mount the rotator inside, and not on top.

    Be careful.:)
     

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