Richard,
I just remembered, there will be three tiers of guy wires (four wires at
each level), one set at the top, one set ten feet down from that, another
ten feet down from that,etc.. Can all of these guy wires be part of the
antenna system? Like you mentioned, kind of a "umbrella skeleton". It might
be tricky to make sure that the guy wires both bond to the circular ring
around the mast which the wires attach to, and to make sure that this metal
ring also bonds well to the mast, I will have to think about a good
technique here. I guess I could carefully weld them in place (normally they
are tightly fitted to the pole, but can still slide up or down), I am sure
you have seen these old tv telescoping masts, they seem fairly standard.
Bill
zeno wrote:
Hi Richard,
I think at least one of the metal masts I will be using to hang the 160m
loop might lend itself to the vertical antenna you suggest. It is the one
that is a full 50' in height, and will be out in the middle of the
orchard where ground radials can be installed easily. Unfortunately this
particular mast is the one farthest away from the shack, approx. 500
feet.
Questions:
1. For reference purposes, what is the exact description (name) of this
vertical? Any recommendations for information in print about this
concept?
2. What band, or bands, would it be good for? (Assuming the guy wires are
generally in the position of effectivenes as guy wires.)
3. Would it be monoband, tuned to an exact f, or possibly multiband?
4. Where would one attach the feed line and would a run of 500' to the
shack still be worth the effort?
5. If I understand, the antenna is comprised of the mast itself (with
telescoping sections securely and electrically bonded to each other) plus
the "extension" of calculated lengths of the four guy wires, utilizing
insulators at precise points before being attached to ground anchors.
6. How would the mast be mounted to the ground? Should it ideally be
isolated from ground or contiguous with the ground? Theortically I could
build a short wooden platform or something.
7. Other than the mast itself, the four guy wires, and some kind of
system of radials in the ground, are there any other elements to this
antenna that I should know about or be thinking about?
Bill
Richard Clark wrote:
On Sat, 17 Apr 2004 18:14:58 GMT, zeno wrote:
I am getting ready to put up my masts (5 of them) for a 160m
full wave loop. For the most part I am using recycled
telescoping tv masts which will be up around 50+ feet.
Hi Bill,
You are on the threshold of being able to do much more for slightly
more effort.
Let's suppose you use wire with insulators to break them up (generally
only advised as a must below tower mounted beams so that opportunistic
resonances don't mess up directionality and tune).
Further, let's suppose all wires at the top have a good metal
connection to the mast.
Further, let's suppose each of these wires is broken such that the
first insulator(s) is more than 25 or 30 feet above ground (straight
down, I am not measuring along the wire).
Nothing else matters beyond what you would then do for general
construction.
I presume that all masts are driven into the ground (or at least are
not insulated from ground); and that at each mast you could build a
radial ground screen of eight to a dozen wires as broad as those first
set of insulators are out from the mast (probably 20 to 30 feet each).
You then have the opportunity of developing four broadband vertical
antennas (each with a gamma feed because of the grounded situation).
There's a good chance they would operate on 80M without too much
effort (you might push them to 160).
Most of the work is in the top connection, and the first set of
insulators - beyond that no commitments are needed if you simply
decide to walk away later. That is easy with little difference in the
up front effort.
73's
Richard Clark, KB7QHC
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