I have had several requests to post the responses received pertaining to
phasing inverted-L's, so they are:
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RE>TopBand: 160 meter phased inverted-L's 12/16/96
Hi Ken, it doesn't matter which way the ends point. Mine point in the same
direction,
because that's the way the trees are located to support the L's.
73, Peter WW2Y
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Ken
Pointing the tails at each other is not the right way to do it. You want to
preserve that 1/2 wave spacing which is far less than a 1/2 wave if the tails
are so oriented.
I make the tails parallel to each other and also 1/2 wave spaced. It doesnt
really matter which way, but if EU is your objective, aim the two tails SW if
you can rather than NE. It may buy you 1db of a better sig in Europe.
73 Jeff k1ZM@aol.com
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The computer models indicate that if you are feeding the L's in phase
(broadside) there is a slight advantage in having the L's point at each
other. This is theoretically .5db to 1.5db over all the other possible
permutations. I dont remember which permutation is the worse. This ONLY
applies in the BROADSIDE case. Other phasings have other optimal wire
placement.
My 1/2 wave spaced L's point at each other by luck of the available
organic antenna towers (trees) that I have to work with. My L's are set
up to switch in 180 degree of phase shift in one leg so I can go endfrie
as well.
For the sake of a few tenths of a db I wouldn't woryy about it a lot.
Put your time, worry and effort into the ground system.
Dave
N7EX
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Ken, they can be pointed at each other or parallel to each other. Pointing
them towards (or away) from each other keeps everything in one plane
and requires only two supports. If they are parallel it would require
four supports (three if they converged on the third support). By pointing
them
towards each other the required spacing on the supports is reduced.
By having them in a line they also tend to cancel out some of the
horizontal component radiated by each of them. Pointing them
together makes them closer and should more effectively cancel
the horizontal stuff. Probably not a major factor since the tops are
at low current points and the bottoms (high current points) do most
of the radiating.
So there are minor mechanical and electrical reasons to point them
towards each other--but if site conditions prevent it then just do
what you can.
73 John W0UN
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The spacing is usually 1/4 wave and sometimes even 1/8 wave. The AO
program indicates that the tops should both face the same direction for
best F/B. Facing them at each other results in increased mutual
coupling. If the ends touched you would have a "Half Square" and a
broadside pattern instead of end-fire.
73................Carl
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At one time I explored the possibility of adding some top loading to
my 80m verticals for use on 160m. The easiest way seemed to be to add
wires from the tops of the verts towards each other. However, when I
modeled this using AO, I found the front to back ratio was way down!
After thinking about it for a while, it became clear that this was due
to the incoming skywave inducing currents in the top loading wires that
flow in opposite directions. Therefore, incomplete cnacellation. If you
want good F/B in an endfire array, arrange the top loaders to be
parallel to each other. If DX is your main interest on 160, you might
think about a "T" configuration. Less high angle radiation due to
symmetrical layout.
73 and Happy Holidays
Roger
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I wouldn't worry too much about it. It is an issue, but not a
major one.
I have a 1/8 wave spaced inverted-L array. When I was modeling it,
I tried looking at what moving the azimuth of the horizontal section
did.
But since most of the radiation comes from the vertical part, we
are really only speaking about the small amount of horizontally
polarized radiation that the horizontal section might put out.
In that case, I found the pattern slightly cleaner (more symmetrical)
with the horizontal sections paralllel with each other on the same
side.
In practice though, my array has the sections parallel but on
opposite sides of the array. It seems to work gud enuf for me,
what a fantastik receive antenna with the noise reduction putting
on a pattern causes.
73 and gl
Brian N3OC
(ex WA3WJD)
=================================================
Hope this helps some potential topbanders, it answered my questions.
Thanks again to all responding!
73's Ken K8ZR
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