[Elecraft] Don't be shy--go ahead and ask! (OK, here's one about antennas)

[Tom, W6WW]

I don't have an answer to your question, but rather an expansion.  What
about a horizontal full-wave loop? I've read they don't need to be high, and
the perimeter of your house might be the beginning of a loop for 80m.  But
if we cannot get a full wave that way, what if we used a Slinky-type loop to
make up the difference?  Anyone hear of such a thing?

73
Tom, W6WW



> I've got a question or two about putting up an antenna in a very
difficult,
> maybe impossible, location. I want to put up a wire antenna so I can get
on
> 80, or even 80 & 160. (I've got a roof-mounted vertical for 40-10M.) The
> problem is that we've got a very small lot and what with neighbors,
> powerlines, sidewalks, etc., there's nowhere to put it except IN our one &
> only tree...
>
> The tree is about 40 ft tall but of course all the top-most branches are
too
> small to support a wire, the same with the ends of branches around the
> circumference of the tree. I'd guess the useable height is 30-32 ft and
> useable diameter is maybe 25-30 ft. The tree's center is only about 30ft
> from the 2nd floor shack.
>
> I can imagine 3 possibilities. (Other designs don't seem possible or
> useful--for example, an inverted-L (over the top of the tree & down the
> opposite side) would be only 50-60ft long & isn't that too short to be
> useful on 80, not to mention 160?)
>
> 1. Run a longwire over to the tree and then spiral it down (or up, if that
> would be more effective) like Christmas lights. I suppose I could wrap at
> least 150ft of wire if each loop was 3-4 ft from the next. Think of it as
a
> very large coil.
>
> 2. Make a "wire cage" like the Antenna Book shows on page 6-10, Fig. 19-D.
> This would be much larger though, I suppose 6 or 8 vertical elements, each
> one would be about 20 ft & the overall diameter of the cage 25-30ft. This
> design could easily use 300ft of wire & with extra vertical elements,
more.
> However, I'd have to use an 8-ft rod for the ground as there isn't any way
> to put down radials.
>
> 3. Put up a civilian-style AS-2259 NVIS cloudburner, running coax over to
> the top of the tree & then, from both braid & center, have 25 & 38 ft
> elements drooping downwards (although the 4 elements would be parallel
more
> than pyramid-shaped).
>
> These may be goofy ideas but I haven't found anything in my ARRL books to
> give me a direction to follow. Normal antennas run between things, not in
> them or around them. Even if I knew how to model antennas, I don't know if
> it's possible to model, say, Christmas tree lights without any bulbs!!
Also,
> it might be that the nearness of leaves & branches will make it impossible
> to get on the air (obviously,  I'd have to use durable, well-insulated
wire
> to protect against abrasion from branches, moisture shorts, etc.).
> Basically, I know I'll have to make big compromises to get on even 80, but
> if I could have an antenna that gets one watt out of the five out into the
> ether, heck, I'd have the world at my doorstep!
>
> My questions:
> --Do any of these ideas seem useable?
> --Am I missing a better alternative?
> --Would the best antenna design possibility for this situation be even
> better with one specific type of ATU (as in, What's the best way to match
a
> K2 to a giant wire cage that's up in the maple tree in your front yard?)?
>
> Thanks for putting some creative energy into this!
> 72/73,
> Max, k0max
> PS: It isn't possible to put up a tower in place of the tree and stay
> married. Even UHF is a better idea than the chainsaw <g>
>
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