[TowerTalk] [800 M longwire] Basic question...

[Bgsalesmel@cs.com]

Message: 7
Date: Thu, 13 Oct 2005 10:54:17 -0500
From: K4SAV <RadioIR at charter.net>
Subject: Re: [TowerTalk] Wire Size for 800 meter longwire
To: towertalk at contesting.com
Message-ID: <434E8329.4010704 at charter.net>
Content-Type: text/plain; charset=us-ascii; format=flowed

<snip>
The pattern formed by a long wire is very complex. There are large 
numbers of lobes and nulls, both in the azimuth and elevation 
directions. Most of these are very narrow. Because of this any small 
phase change in the current, causes large changes in the pattern. 

<snip>

Jerry, K4SAV 

<< My question >>

The QTH has Available a 800M run over saltwater...great.
He is limited as to "what" he can hang due to mechanics...awww shucks.
The "far end" is on another's land/fence post - can't be fed from there, 
right?
The "pull" measured in pounds is only calculated at 500# or less, with 
variables...

IS it "written" someplace that he has to use the entire span for the active 
antenna???

Everyone is bemoning this pattern variable at this length...vs frec, dia, 
etc.
I seem to recall something from an old ARRL Ant book about "5 wave/frec 
lenth"...

Why not consider using one of those "fat" (strong?) guy insulators to adjust 
the active length near the mid point "FROM" the far end? Should yield 
something like a sloper fired from the high end I would think...maybe even play with 
some sort of balast or top loading done "onshore", or short hanging "tail" at 
the midpoint...computer models should show whatever this could yield, pro 
and/or con. I'm thinking of some sort of "vertical" component effect here. Maybe 
even use another insulator on the "near/fired" end to displace the active length 
more "over water"?? The attachment line could be used as a messenger line for 
the feed source, eh? OR, it might model better with a free "drooping" 
feedline config? I think he said he had about 70ft of height to work with 
onshore...don't know "what" is downslope from his anchor point...maybe a cliff? 

The mechanics then just become an engineering and materials function.... :-(

Just some different thoughts for an already interesting thread... 73 to all.

Mel Frost KD7DCR
Coeur d'Alene, ID