Opinions on Vertical Antennas?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WC3T, Oct 2, 2015.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    That's unusual. 1500 yards for the nearest distribution line would mean your service drop is close to a mile away....1500 yards for a 120-0-120 line is really, really far. Either that's an enormously large line or you're confusing a high tension line with a distribution line.

    Normally low voltage service drops are a few hundred feet or less.
     
  2. WC3T

    WC3T Premium Subscriber QRZ Page

    I thought you meant high tension. The distribution lines and everything in the development are buried.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If everything's buried, what's the power lines you referred to...
     
  4. WC3T

    WC3T Premium Subscriber QRZ Page

    Large high tension lines about 1500 yards from the house. That's as close as any power lines get, unless I plug an extension cord into an outside service outlet. :)
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Okay I get it now. You wrote 'where the utilities come in' and didn't specify what they were; I assumed you meant the AC power service.

    My mistake, you meant something else. ANYTHING else is not dangerous and I'd put antennas anywhere I want around cable TV or telephone lines. They're well grounded and harmless.
     
  6. KM1H

    KM1H Ham Member QRZ Page

    An inverted vee is predominantly a horizontal radiator and always was.

    Open wire line is only balanced when there is no reactance on it and then it becomes a radiator of some degree, that is the only way you will get vertical radiation except some small amount directly off the ends of the dipole...which is disputed in some models.
    Open wire line to a ~ 50-75 Ohm antenna already has a substantial VSWR on it and a 1:1 balun guarantees a serious unbalance.

    Your description is a mirror pair of inverted L's and depending upon what happens at the tuner the horizontal radiaton from the top will be reduced to canceled as would a perfect T top capacity hat. Many on the lower bands use an inverted L to great benefit as they have both polarizations available.

    With the lower half of the dipole being substantially shortened on the lower bands plus the need for tuning wires, aka radials, and specific coax lengths it is really a modified 1/4 wave vertical with elevated radials and a radiating coax. With a substantially shortened upper half radiator short radials work and more of the same should work better.

    Carl
     
  7. KB1CKT

    KB1CKT Ham Member QRZ Page

    My 6btv is located at the edge of my leechfield. It does not work as bad as one might think... I wonder if you could dig down and bury a metal plate or whatever to mount a very short mast to--or just find the pipes, the drive the antenna mast between them. Then run radials over the field. The whole point of radials is to make a lower impedance path than soil, so I am not sure if having sand underneath matters--just put down lots of radials.
     
  8. AE7XG

    AE7XG Ham Member QRZ Page

    I have a highgain AVQ-18 5 band trap vertical. no radials. works just fine , staked and just above ground. I contac ZS3D in Africa, seems to work. My suggestion is try to find one used , you can still buy the traps from mfj. They even work better when you set up radials.
    I live in an HOA so mine is kind of hiddin.
     
  9. W9XMT

    W9XMT Ham Member QRZ Page

    A center-fed, 1/2WL vertical dipole needs no connection to an earth r-f ground to radiate with nearly 100% efficiency. But reflections of its radiated fields off the earth still are important in forming the radiation pattern -- as shown in the graphic below (this pattern is based on zero radiation from the feedline).

    [​IMG]
     
  10. KM1H

    KM1H Ham Member QRZ Page

    That appears to have the feed point at a 1/2 wave above average ground so the bottom is at 1/4 wave above ground and adequately isolated/decoupled from it. Now compare that to one with the feed point 16' high over the same ground and also with a 1 mS/m ground. Since NEC4 doesnt like to work accurately right at ground level you can raise it an inch or so.

    Then compare to a 1/4 wave with 4-8 elevated radials at 16' high.

    My own ground is in the 0.5 mS/m range (hilltop with solid granite 7-24" down) and with elevated radials verticals work well and far outperform vertical dipoles for low angle DX AND groundwave with the bottom at almost ground level in A:B tests Ive ran on 80/40/20M in the past. And yes I have tower and tree branch heights to do that.
     

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