inverted V counterpoise near powerline

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K7OQN, Sep 17, 2016.

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  1. K7OQN

    K7OQN Ham Member QRZ Page

    I need some advice re an inverted v I am installing on my lot. It will have a 130 ft Horiz run with a 35' vertical. I have a 135' back fence with a another fence approx 60 degrees away and another at 120 degrees. the far fence is 5' high and runs 135' as well. The later fence line is located near a high voltage feeder line above. the vertical separation is approx 75' and it is 20' away laterally. I know the V is noisy but I opted for counterpoise vs ground radials due to lot config and have a 350' loop that I plan to use as a receiving antenna.

    I want to work 160/80 and 40. My question is regarding Counterpoise running below the high voltage line. What should I expect with that counterpoise? Issues of possible coupling?? I want to run at least 3 counterpoise lines they will all be 125' plus. If I drop the one below the power line that only leaves me two lines that are 60 degrees apart. I could run another parallel to the one I have on the fence but there would only be 12" separation and I would not expect that to make much difference.

    See Attached for proposed view

    Any help would be appreciated. Tried to run EZNEC but just not proficient yet.

    Thanks/Bob/K7OQN
     

    Attached Files:

  2. WA7DU

    WA7DU Ham Member QRZ Page

    None of your attachments will open on my iOS device. I was hoping they would explain your proposed set up--your written description leaves me confused.

    When you write "counterpoises" are you referring to elevated radials ? For which antenna are you installing counterpoises ? Is your loop antenna unbalanced ? I'm not understanding what the counterpoises are for.


    I think I understand that there will be both vertical and horizontal separation between the power lines and any of your wires. If so, that is good.

    If you are concerned about power line noise coupling to your antenna(s), one of QRZ.com's luminaries (the WB2) has antennas close to power lines without noise problems. So, we know that it can be done. Perpendicularity will certainly help. What do the powerlines carry, what voltage ?

    I am going to see if I can open your attachments with some voodoo. Meanwhile...
     
  3. K4SAV

    K4SAV Ham Member QRZ Page

    All three of the pdf files seem to be of the same thing. I don't see any difference between them. I still have to guess at the configuration but my guess is that it is an end fed bent wire with 3 counterpoise wires. The end fed wire may be sloping to 35 ft in the middle, then sloping back down to 5 feet at the end. I think maybe the counterpoise wires are running on a fence, so they are probably pretty low.

    How close did I get?

    It is really a quadri-pole antenna and with enough messing around with all the wires you could get some resonances in strange places. Adjustment may take a while if you are trying to get low SWR on 3 bands. I doubt that you will make it on 160, but 80 and 40 should be possible with a 4 to 1 balun.

    Gain should be pretty low because the wires are very low, so ground loss will be high.

    Jerry, K4SAV
     
    WB5YUZ likes this.
  4. K8JD

    K8JD Ham Member QRZ Page

    Same here with the 3 identical PDF drawings, leaves me more confused. An inverted Vee in modern references usually is a dipole with a high center feedpoint and lower ends.
    This one is a real unknown.
    A dipole of the inverted vee configuration needs no counterpoise since it is an balanced antenna.

    The CLASSIC inverted vee is a multiple wavelength end fed with a well known apex angle designed for maximum bidirectional gain at certain frequencies.
    Is that what the original poster is going for ?

    My only advice is keep any antenna wire from being close to and parallel to a power line!
    That's an invitation to induce a lot of noise into the receiver !
     
  5. N0FN

    N0FN Ham Member QRZ Page

    I think that he means an inverted L with elevated radials. I had very good luck investigating the effects of second and third radials using an EZNEC model for my 80/160 inverted L.

    This is one of the simplest antennas to build a model of and my recollection is that the efficiency improvements after the second elevated radial (mine were about 8 feet high) are rapidly diminishing.

    -Neil N0FN
     
  6. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    I think Jerry is right; this antenna is going to take a lot of fiddling, unless you just stick a good remote tuner at the base of it; and even then, it's probably only going to be a mediocre performer.

    May we ask why you cannot install a more conventional radial field? The one you have described will greatly compromise performance, especially on 160m.
     
  7. K7OQN

    K7OQN Ham Member QRZ Page

    OK Had a few responses and I did copy my attachment. Haven't posted before so please pardon the mistake.

    Yes this will be an inverted L. The feed point will be at the conjunction of the counterpoise elements and the vert bottom of the L. .

    The counterpoise being parallel to the Power Line is my main concern. All counterpoise elements are 3-5' from the ground.

    Re Ground based radials vs Elevated (Counterpoise) -- I do not have a way to add multiple ground based radials. It is my limited understanding that 2 or 3 Elevated radials will achieve good performance vs 20+ Ground radials. If I only use 2 elev radials they would be at 60 degrees from the feed point. I am concerned that will be sufficient spacing. That's why I wanted to run a third Elev radial that would be at 120 or 140 degrees from the feed point out.

    As for the Antenna itself it would have the Horiz L at 40' high for 130' long. The Vert section of the L would drop to 5' making total length at 160. I do plan to add a tuner to this.

    My Lot is 135 across back and 135 on each side meeting a 90' front

    Hope that helps

    Bob
     
  8. K7OQN

    K7OQN Ham Member QRZ Page

    Sorry I confused you. Haven't posted before. Antenna under proposal is an inverted L. Horiz L is 40+ ft high 130 ft long/ Vert piece is at the feed point and drops to 5' giving total length at 165' (35' vert). Loop is just for listening. Elevated radials are 3-5 ft off ground. The Power line is a 22KV feed about 75' in air. It parallels the Elevated radial CPOSE 3. Concern is whether the Elev radial will be an issue positioned parallel but lots of vert spacing.

    Hope that helps
     
  9. K7OQN

    K7OQN Ham Member QRZ Page

    Sorry I confused you. Haven't posted before. Antenna under proposal is an inverted L. Horiz L is 40+ ft high 130 ft long/ Vert piece is at the feed point and drops to 5' giving total length at 165' (35' vert). Loop is just for listening. Elevated radials are 3-5 ft off ground. The Power line is a 22KV feed about 75' in air. It parallels the Elevated radial CPOSE 3. Concern is whether the Elev radial will be an issue positioned parallel but lots of vert spacing.

    Hope that helps
     
  10. K7OQN

    K7OQN Ham Member QRZ Page


    Inverted L not V. End fed at bottom of vertical portion of L
     

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