[TowerTalk] Vertical question

[Artek Manuals]

Mike

Based on the models I have seen I think your observations are very 
realistic.

With inverted L's there will be a slight degradation ( 1.5 to 3db) in 
the direction the top of the L "points" so to speak. With your 
asymmetrical elevated radials there will also be some pattern 
"distortion" as well. This maybe compensate or further degrade the 
pattern in the direction that the L "points"

If you will send me some X/Y/Z ordinates for all 5 wires for your in 
2radial inverted J I wll be happy to run a model of it. I have a good 
idea on the "J " itself but where the radials are under the J is not 
clear to me

Dave
NR1DX
manuals at artekmanuals.com

On 3/16/2021 10:14 AM, Mike Smith VE9AA wrote:
> de VE9AA
>
>   
>
> Because I am a doubting Thomas type of guy when it comes to trusting
> folklore about antennas, I actually tried this as a real world test a few
> years ago.
>
>   
>
> I have 2 x 160m inverted L's here 120' apart.  Both go up (sloped) around
> 50-60', then over 50-60', then down 20 feet or so. (like an inverted J)
>
> They're not perfectly symmetrical, but were close enough to satisfy my
> curiosity.
>
>   
>
> One has 2 raised radials aprox 10' high and 127' long @ 90* to one another.
> (180* would be better, but I don't have the room)
>
> This one overall is a little lower and lazier than the other one and one
> radial zig-zags a little up/dn and around  the corner of the property. (just
> the way the trees are here).nothing is perfect here.
>
>   
>
> The other inverted J, has many thousands of feet of copper in and on the
> surface of the ground. I started with about 60+ 127' radials, so that
> equates to about 7620' of radials, but I've lost a few over the years due to
> the mower, a gopher, me tripping,  etc.  Let's say I have even only 6620' of
> radials on the ground. They're not perfectly symmetrical around the vertical
> either though due to constraints in the yard, having most of the radials in
> the southern hemisphere of the antenna and only a few bent ones north ,
> northwest or northeast of the antenna.
>
>   
>
> What I found was that:
>
> Most of the time through an A/B switch the verticals were close enough that
> I would really be guessing which one was loudest/best and other times the
> one with all the 60 on-ground radials was definitely best by a small margin.
> I can't ever say with confidence the one with 2 raised radials was best.
>
>   
>
> My test is slightly flawed not only because both antennas are not perfect
> copies of one another, but I didn't short or open either one when doing my
> tests and there are lots of antennas in the near field to both, but
> especially closer to one of them.  This testing was before I was used to
> using the RBN and what it could do for me.  Today I would definitely do
> proper RBN comparisons for sure. Maybe that would open my eyes to a larger
> difference or maybe it would show nothing. One is left guessing.
>
>   
>
> As it was, I just listened to DX stations. QSB and whatnot makes this tough
> to call.
>
>   
>
> It was enough though to tell me that 2 raised radials was "good enough" for
> the type of radio work I do. Is it down a dB or two? (probably)
>
>   
>
> If I owned a copper mine or was wealthy then I would definitely do 120 on
> ground radials for each of them.(or maybe 8 raised radials if I had the
> land, but I don't)
>
>   
>
> I would also do the same for all my 4-squares, however all my 4 squares
> (20-40-80 and soon 10 & 15) will just have 2 raised radials each.
>
>   
>
> Scientific? Not exactly, no.
>
>   
>
> Better than anecdotal (imo) - yes !
>
>   
>
> FWIW to y'all
>
>   
>
> Mike VE9AA
>
>   
>
> =================
>
> How do you know that there is a huge difference?
>
>   
>
> John KK9A
>
>   
>
> Jim N9WW wrote:
>
>   
>
> I'll take my elevated 40/30M vertical at 30' with 8 radials over any ground
> mounted vertical with 60+ radials. Been there done that. Huge difference.
>
>   
>
> 73,
>
> Jim N9WW
>
>   
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>   
>
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>
>
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-- 
Dave Manuals at ArtekManuals.com www.ArtekManuals.com

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