All:
I put up a pair of phased verticals for 80 on the slope of a hill.
The verticals are wire supported by 60' spiderbeam poles. I picked a spot
where the antenna bases were as level as possible but the hill slopes up to
the east, less so to the northeast. There are 16 radials per vertical. A
DXE box is used for phasing. Soil is a layer of forest loam over
sandy soil. The loam stays moist for most of the year given that
accumulated rain drains down the hill and under the antennas. I tuned the
antennas per the DXE manual. My reference antenna is an OCF dipole, apex
70' near the top of the hill.
The verticals are considerably quieter on receive than the dipole
allowing to to work stations I would otherwise not have been able to hear.
I was also pleasantly surprised at the number of pileups I was able to
break. I also had a couple of limited runs to EU. Overall, I'm happy with
this so far. It's definitely an improvement over the dipole.
However, I'm thinking of an improvement. On 160 I have an inverted L that
uses a folded counterpoise described by K2AV instead of radials. This is
the best 160 antenna I have ever used at this location. For 80, I'm
thinking of replacing the radials with folded counterpoises on both
verticals. Has anyone here done that?
73
John
NN1SS
On Fri, Apr 11, 2025 at 6:21 PM Jim Lux <jim@luxfamily.com> wrote:
>
>
>
>
> They are "exactly" like Yagi antennas... They're both phased arrays, just
> one has all driven elements, and the other has elements that are passively
> coupled to a single driven element.
>
> yeah, a few degrees isn't necesarily a big deal.
> As I commented, local soil properties under and between the radiators
> might have a bigger effect. The box forces the element currents to be
> right, but for the same element current, how much gets radiated depends on
> the soil losses in the near field. Perhaps you could flood your field with
> some small dikes, akin to rice paddies? Salting it probably doesn't add
> much. It's that 80 epsilon water that makes the air/soil boundary
> reflective.
>
>
>
> On Fri, 11 Apr 2025 14:48:26 -0400, <john@kk9a.com> wrote:
>
> Thanks Jim for your detailed response. I could have worded this better, In
> the location that I roughly laid out my 4square pattern the difference
> between the lowest and highest base is 5 feet. I may be able to improve the
> height difference slightly moving the pattern around slightly in that
> pasture. Going across the 80m 4sq diagonal, 5 ft low is only 3° out of
> level. So maybe I am being overly concerned. VE9AA has 4 squares much more
> out of level that that and he's happy with them plus I never had trouble
> working Mike for the Sweepstakes mult. I did not consider that phased
> verticals may be like Yagi's where F/B is more easily effected by system
> imperfections than gain.
>
> 73
> John KK9A
>
>
> Jim Lux wrote:
>
> This is where modeling can help you tell if it's a big deal or a little
> deal.
>
> The DX engineering box is a L network for phase and you have 1/4 wave
> transmission lines to the elements - so that's easily doable in NEC (of any
> flavor).
>
> At first, I'd think you'll get some sort of tilt in the vertical pattern,
> but
> not much, and I think other factors might have a bigger effect (for
> instance,
> is the soil exactly the same over the entire array area).
>
> 5 feet out of 60 feet isn't a huge angle (5 degrees?).
> You say you can get the height the same within 5 feet? Is that by raising
> or
> lowering the antenna on a post at the location? That might have a bigger
> effect because it will change the feedpoint impedance, and notwithstanding
> the
> "current forcing" feature of 1/4 wave TLs, it does result in a change.
>
> FWIW, you won't notice much change in forward gain with almost any
> installation
> imperfections. What you'll notice is that the nulls aren't where you expect
> and
> may not be as deep. So you need to look at *what do you expect to get out
> of a
> 4 square".
>
>
> On Mon, 7 Apr 2025 15:26:16 -0400, wrote:
>
> A year ago I moved to a beautiful 17 acre property. It is all open with
> lots of grass to mow. I would like to put up an 80m 4 square, I have a DX
> Engineering phasing unit, controller and four freestanding verticals. The
> problem is, the property slopes down from the house and it is also rolling
> up and down so It is difficult to find a flat spot on higher areas for the
> four verticals. To complicate matters there is a residential power line
> running across the middle which seems to be on the higher spots of the
> rolling terrain. The DXE manual states the base height should differ less
> than 20% of the array diameter and it gives an example of 12 feet. I am
> assuming array diameter means distance between verticals. I am sure that I
> can get the base heights within 5 feet on a higher area of the property but
> even that seems like a lot. What effect does base height have on a vertical
> array? I could probably could have less base height differences if I placed
> it in a valley with the 6 foot rolling hill next to and above it so the
> radials would be going uphill, is that a better option? I am not interested
> in elevated radials.
>
> 73,
> John KK9A
> http://www.kk9a.com
>
>
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